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2    * Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
3    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4    *
5    * This code is free software; you can redistribute it and/or modify it
6    * under the terms of the GNU General Public License version 2 only, as
7    * published by the Free Software Foundation.  Oracle designates this
8    * particular file as subject to the "Classpath" exception as provided
9    * by Oracle in the LICENSE file that accompanied this code.
10   *
11   * This code is distributed in the hope that it will be useful, but WITHOUT
12   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14   * version 2 for more details (a copy is included in the LICENSE file that
15   * accompanied this code).
16   *
17   * You should have received a copy of the GNU General Public License version
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19   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20   *
21   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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24   */
25  
26  package java.lang;
27  
28  import java.lang.ref.Reference;
29  import java.lang.ref.ReferenceQueue;
30  import java.lang.ref.WeakReference;
31  import java.security.AccessController;
32  import java.security.AccessControlContext;
33  import java.security.PrivilegedAction;
34  import java.util.Map;
35  import java.util.HashMap;
36  import java.util.concurrent.ConcurrentHashMap;
37  import java.util.concurrent.ConcurrentMap;
38  import java.util.concurrent.locks.LockSupport;
39  import sun.nio.ch.Interruptible;
40  import sun.reflect.CallerSensitive;
41  import sun.reflect.Reflection;
42  import sun.security.util.SecurityConstants;
43  
44  
45  /**
46   * A <i>thread</i> is a thread of execution in a program. The Java
47   * Virtual Machine allows an application to have multiple threads of
48   * execution running concurrently.
49   * <p>
50   * Every thread has a priority. Threads with higher priority are
51   * executed in preference to threads with lower priority. Each thread
52   * may or may not also be marked as a daemon. When code running in
53   * some thread creates a new <code>Thread</code> object, the new
54   * thread has its priority initially set equal to the priority of the
55   * creating thread, and is a daemon thread if and only if the
56   * creating thread is a daemon.
57   * <p>
58   * When a Java Virtual Machine starts up, there is usually a single
59   * non-daemon thread (which typically calls the method named
60   * <code>main</code> of some designated class). The Java Virtual
61   * Machine continues to execute threads until either of the following
62   * occurs:
63   * <ul>
64   * <li>The <code>exit</code> method of class <code>Runtime</code> has been
65   *     called and the security manager has permitted the exit operation
66   *     to take place.
67   * <li>All threads that are not daemon threads have died, either by
68   *     returning from the call to the <code>run</code> method or by
69   *     throwing an exception that propagates beyond the <code>run</code>
70   *     method.
71   * </ul>
72   * <p>
73   * There are two ways to create a new thread of execution. One is to
74   * declare a class to be a subclass of <code>Thread</code>. This
75   * subclass should override the <code>run</code> method of class
76   * <code>Thread</code>. An instance of the subclass can then be
77   * allocated and started. For example, a thread that computes primes
78   * larger than a stated value could be written as follows:
79   * <hr><blockquote><pre>
80   *     class PrimeThread extends Thread {
81   *         long minPrime;
82   *         PrimeThread(long minPrime) {
83   *             this.minPrime = minPrime;
84   *         }
85   *
86   *         public void run() {
87   *             // compute primes larger than minPrime
88   *             &nbsp;.&nbsp;.&nbsp;.
89   *         }
90   *     }
91   * </pre></blockquote><hr>
92   * <p>
93   * The following code would then create a thread and start it running:
94   * <blockquote><pre>
95   *     PrimeThread p = new PrimeThread(143);
96   *     p.start();
97   * </pre></blockquote>
98   * <p>
99   * The other way to create a thread is to declare a class that
100  * implements the <code>Runnable</code> interface. That class then
101  * implements the <code>run</code> method. An instance of the class can
102  * then be allocated, passed as an argument when creating
103  * <code>Thread</code>, and started. The same example in this other
104  * style looks like the following:
105  * <hr><blockquote><pre>
106  *     class PrimeRun implements Runnable {
107  *         long minPrime;
108  *         PrimeRun(long minPrime) {
109  *             this.minPrime = minPrime;
110  *         }
111  *
112  *         public void run() {
113  *             // compute primes larger than minPrime
114  *             &nbsp;.&nbsp;.&nbsp;.
115  *         }
116  *     }
117  * </pre></blockquote><hr>
118  * <p>
119  * The following code would then create a thread and start it running:
120  * <blockquote><pre>
121  *     PrimeRun p = new PrimeRun(143);
122  *     new Thread(p).start();
123  * </pre></blockquote>
124  * <p>
125  * Every thread has a name for identification purposes. More than
126  * one thread may have the same name. If a name is not specified when
127  * a thread is created, a new name is generated for it.
128  * <p>
129  * Unless otherwise noted, passing a {@code null} argument to a constructor
130  * or method in this class will cause a {@link NullPointerException} to be
131  * thrown.
132  *
133  * @author  unascribed
134  * @see     Runnable
135  * @see     Runtime#exit(int)
136  * @see     #run()
137  * @see     #stop()
138  * @since   JDK1.0
139  */
140 public
141 class Thread implements Runnable {
142     /* Make sure registerNatives is the first thing <clinit> does. */
143     private static native void registerNatives();
144     static {
145         registerNatives();
146     }
147 
148     private volatile char  name[];
149     private int            priority;
150     private Thread         threadQ;
151     private long           eetop;
152 
153     /* Whether or not to single_step this thread. */
154     private boolean     single_step;
155 
156     /* Whether or not the thread is a daemon thread. */
157     private boolean     daemon = false;
158 
159     /* JVM state */
160     private boolean     stillborn = false;
161 
162     /* What will be run. */
163     private Runnable target;
164 
165     /* The group of this thread */
166     private ThreadGroup group;
167 
168     /* The context ClassLoader for this thread */
169     private ClassLoader contextClassLoader;
170 
171     /* The inherited AccessControlContext of this thread */
172     private AccessControlContext inheritedAccessControlContext;
173 
174     /* For autonumbering anonymous threads. */
175     private static int threadInitNumber;
176     private static synchronized int nextThreadNum() {
177         return threadInitNumber++;
178     }
179 
180     /* ThreadLocal values pertaining to this thread. This map is maintained
181      * by the ThreadLocal class. */
182     ThreadLocal.ThreadLocalMap threadLocals = null;
183 
184     /*
185      * InheritableThreadLocal values pertaining to this thread. This map is
186      * maintained by the InheritableThreadLocal class.
187      */
188     ThreadLocal.ThreadLocalMap inheritableThreadLocals = null;
189 
190     /*
191      * The requested stack size for this thread, or 0 if the creator did
192      * not specify a stack size.  It is up to the VM to do whatever it
193      * likes with this number; some VMs will ignore it.
194      */
195     private long stackSize;
196 
197     /*
198      * JVM-private state that persists after native thread termination.
199      */
200     private long nativeParkEventPointer;
201 
202     /*
203      * Thread ID
204      */
205     private long tid;
206 
207     /* For generating thread ID */
208     private static long threadSeqNumber;
209 
210     /* Java thread status for tools,
211      * initialized to indicate thread 'not yet started'
212      */
213 
214     private volatile int threadStatus = 0;
215 
216 
217     private static synchronized long nextThreadID() {
218         return ++threadSeqNumber;
219     }
220 
221     /**
222      * The argument supplied to the current call to
223      * java.util.concurrent.locks.LockSupport.park.
224      * Set by (private) java.util.concurrent.locks.LockSupport.setBlocker
225      * Accessed using java.util.concurrent.locks.LockSupport.getBlocker
226      */
227     volatile Object parkBlocker;
228 
229     /* The object in which this thread is blocked in an interruptible I/O
230      * operation, if any.  The blocker's interrupt method should be invoked
231      * after setting this thread's interrupt status.
232      */
233     private volatile Interruptible blocker;
234     private final Object blockerLock = new Object();
235 
236     /* Set the blocker field; invoked via sun.misc.SharedSecrets from java.nio code
237      */
238     void blockedOn(Interruptible b) {
239         synchronized (blockerLock) {
240             blocker = b;
241         }
242     }
243 
244     /**
245      * The minimum priority that a thread can have.
246      */
247     public final static int MIN_PRIORITY = 1;
248 
249    /**
250      * The default priority that is assigned to a thread.
251      */
252     public final static int NORM_PRIORITY = 5;
253 
254     /**
255      * The maximum priority that a thread can have.
256      */
257     public final static int MAX_PRIORITY = 10;
258 
259     /**
260      * Returns a reference to the currently executing thread object.
261      *
262      * @return  the currently executing thread.
263      */
264     public static native Thread currentThread();
265 
266     /**
267      * A hint to the scheduler that the current thread is willing to yield
268      * its current use of a processor. The scheduler is free to ignore this
269      * hint.
270      *
271      * <p> Yield is a heuristic attempt to improve relative progression
272      * between threads that would otherwise over-utilise a CPU. Its use
273      * should be combined with detailed profiling and benchmarking to
274      * ensure that it actually has the desired effect.
275      *
276      * <p> It is rarely appropriate to use this method. It may be useful
277      * for debugging or testing purposes, where it may help to reproduce
278      * bugs due to race conditions. It may also be useful when designing
279      * concurrency control constructs such as the ones in the
280      * {@link java.util.concurrent.locks} package.
281      */
282     public static native void yield();
283 
284     /**
285      * Causes the currently executing thread to sleep (temporarily cease
286      * execution) for the specified number of milliseconds, subject to
287      * the precision and accuracy of system timers and schedulers. The thread
288      * does not lose ownership of any monitors.
289      *
290      * @param  millis
291      *         the length of time to sleep in milliseconds
292      *
293      * @throws  IllegalArgumentException
294      *          if the value of {@code millis} is negative
295      *
296      * @throws  InterruptedException
297      *          if any thread has interrupted the current thread. The
298      *          <i>interrupted status</i> of the current thread is
299      *          cleared when this exception is thrown.
300      */
301     public static native void sleep(long millis) throws InterruptedException;
302 
303     /**
304      * Causes the currently executing thread to sleep (temporarily cease
305      * execution) for the specified number of milliseconds plus the specified
306      * number of nanoseconds, subject to the precision and accuracy of system
307      * timers and schedulers. The thread does not lose ownership of any
308      * monitors.
309      *
310      * @param  millis
311      *         the length of time to sleep in milliseconds
312      *
313      * @param  nanos
314      *         {@code 0-999999} additional nanoseconds to sleep
315      *
316      * @throws  IllegalArgumentException
317      *          if the value of {@code millis} is negative, or the value of
318      *          {@code nanos} is not in the range {@code 0-999999}
319      *
320      * @throws  InterruptedException
321      *          if any thread has interrupted the current thread. The
322      *          <i>interrupted status</i> of the current thread is
323      *          cleared when this exception is thrown.
324      */
325     public static void sleep(long millis, int nanos)
326     throws InterruptedException {
327         if (millis < 0) {
328             throw new IllegalArgumentException("timeout value is negative");
329         }
330 
331         if (nanos < 0 || nanos > 999999) {
332             throw new IllegalArgumentException(
333                                 "nanosecond timeout value out of range");
334         }
335 
336         if (nanos >= 500000 || (nanos != 0 && millis == 0)) {
337             millis++;
338         }
339 
340         sleep(millis);
341     }
342 
343     /**
344      * Initializes a Thread with the current AccessControlContext.
345      * @see #init(ThreadGroup,Runnable,String,long,AccessControlContext)
346      */
347     private void init(ThreadGroup g, Runnable target, String name,
348                       long stackSize) {
349         init(g, target, name, stackSize, null);
350     }
351 
352     /**
353      * Initializes a Thread.
354      *
355      * @param g the Thread group
356      * @param target the object whose run() method gets called
357      * @param name the name of the new Thread
358      * @param stackSize the desired stack size for the new thread, or
359      *        zero to indicate that this parameter is to be ignored.
360      * @param acc the AccessControlContext to inherit, or
361      *            AccessController.getContext() if null
362      */
363     private void init(ThreadGroup g, Runnable target, String name,
364                       long stackSize, AccessControlContext acc) {
365         if (name == null) {
366             throw new NullPointerException("name cannot be null");
367         }
368 
369         Thread parent = currentThread();
370         SecurityManager security = System.getSecurityManager();
371         if (g == null) {
372             /* Determine if it's an applet or not */
373 
374             /* If there is a security manager, ask the security manager
375                what to do. */
376             if (security != null) {
377                 g = security.getThreadGroup();
378             }
379 
380             /* If the security doesn't have a strong opinion of the matter
381                use the parent thread group. */
382             if (g == null) {
383                 g = parent.getThreadGroup();
384             }
385         }
386 
387         /* checkAccess regardless of whether or not threadgroup is
388            explicitly passed in. */
389         g.checkAccess();
390 
391         /*
392          * Do we have the required permissions?
393          */
394         if (security != null) {
395             if (isCCLOverridden(getClass())) {
396                 security.checkPermission(SUBCLASS_IMPLEMENTATION_PERMISSION);
397             }
398         }
399 
400         g.addUnstarted();
401 
402         this.group = g;
403         this.daemon = parent.isDaemon();
404         this.priority = parent.getPriority();
405         this.name = name.toCharArray();
406         if (security == null || isCCLOverridden(parent.getClass()))
407             this.contextClassLoader = parent.getContextClassLoader();
408         else
409             this.contextClassLoader = parent.contextClassLoader;
410         this.inheritedAccessControlContext =
411                 acc != null ? acc : AccessController.getContext();
412         this.target = target;
413         setPriority(priority);
414         if (parent.inheritableThreadLocals != null)
415             this.inheritableThreadLocals =
416                 ThreadLocal.createInheritedMap(parent.inheritableThreadLocals);
417         /* Stash the specified stack size in case the VM cares */
418         this.stackSize = stackSize;
419 
420         /* Set thread ID */
421         tid = nextThreadID();
422     }
423 
424     /**
425      * Throws CloneNotSupportedException as a Thread can not be meaningfully
426      * cloned. Construct a new Thread instead.
427      *
428      * @throws  CloneNotSupportedException
429      *          always
430      */
431     @Override
432     protected Object clone() throws CloneNotSupportedException {
433         throw new CloneNotSupportedException();
434     }
435 
436     /**
437      * Allocates a new {@code Thread} object. This constructor has the same
438      * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
439      * {@code (null, null, gname)}, where {@code gname} is a newly generated
440      * name. Automatically generated names are of the form
441      * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
442      */
443     public Thread() {
444         init(null, null, "Thread-" + nextThreadNum(), 0);
445     }
446 
447     /**
448      * Allocates a new {@code Thread} object. This constructor has the same
449      * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
450      * {@code (null, target, gname)}, where {@code gname} is a newly generated
451      * name. Automatically generated names are of the form
452      * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
453      *
454      * @param  target
455      *         the object whose {@code run} method is invoked when this thread
456      *         is started. If {@code null}, this classes {@code run} method does
457      *         nothing.
458      */
459     public Thread(Runnable target) {
460         init(null, target, "Thread-" + nextThreadNum(), 0);
461     }
462 
463     /**
464      * Creates a new Thread that inherits the given AccessControlContext.
465      * This is not a public constructor.
466      */
467     Thread(Runnable target, AccessControlContext acc) {
468         init(null, target, "Thread-" + nextThreadNum(), 0, acc);
469     }
470 
471     /**
472      * Allocates a new {@code Thread} object. This constructor has the same
473      * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
474      * {@code (group, target, gname)} ,where {@code gname} is a newly generated
475      * name. Automatically generated names are of the form
476      * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
477      *
478      * @param  group
479      *         the thread group. If {@code null} and there is a security
480      *         manager, the group is determined by {@linkplain
481      *         SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
482      *         If there is not a security manager or {@code
483      *         SecurityManager.getThreadGroup()} returns {@code null}, the group
484      *         is set to the current thread's thread group.
485      *
486      * @param  target
487      *         the object whose {@code run} method is invoked when this thread
488      *         is started. If {@code null}, this thread's run method is invoked.
489      *
490      * @throws  SecurityException
491      *          if the current thread cannot create a thread in the specified
492      *          thread group
493      */
494     public Thread(ThreadGroup group, Runnable target) {
495         init(group, target, "Thread-" + nextThreadNum(), 0);
496     }
497 
498     /**
499      * Allocates a new {@code Thread} object. This constructor has the same
500      * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
501      * {@code (null, null, name)}.
502      *
503      * @param   name
504      *          the name of the new thread
505      */
506     public Thread(String name) {
507         init(null, null, name, 0);
508     }
509 
510     /**
511      * Allocates a new {@code Thread} object. This constructor has the same
512      * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
513      * {@code (group, null, name)}.
514      *
515      * @param  group
516      *         the thread group. If {@code null} and there is a security
517      *         manager, the group is determined by {@linkplain
518      *         SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
519      *         If there is not a security manager or {@code
520      *         SecurityManager.getThreadGroup()} returns {@code null}, the group
521      *         is set to the current thread's thread group.
522      *
523      * @param  name
524      *         the name of the new thread
525      *
526      * @throws  SecurityException
527      *          if the current thread cannot create a thread in the specified
528      *          thread group
529      */
530     public Thread(ThreadGroup group, String name) {
531         init(group, null, name, 0);
532     }
533 
534     /**
535      * Allocates a new {@code Thread} object. This constructor has the same
536      * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
537      * {@code (null, target, name)}.
538      *
539      * @param  target
540      *         the object whose {@code run} method is invoked when this thread
541      *         is started. If {@code null}, this thread's run method is invoked.
542      *
543      * @param  name
544      *         the name of the new thread
545      */
546     public Thread(Runnable target, String name) {
547         init(null, target, name, 0);
548     }
549 
550     /**
551      * Allocates a new {@code Thread} object so that it has {@code target}
552      * as its run object, has the specified {@code name} as its name,
553      * and belongs to the thread group referred to by {@code group}.
554      *
555      * <p>If there is a security manager, its
556      * {@link SecurityManager#checkAccess(ThreadGroup) checkAccess}
557      * method is invoked with the ThreadGroup as its argument.
558      *
559      * <p>In addition, its {@code checkPermission} method is invoked with
560      * the {@code RuntimePermission("enableContextClassLoaderOverride")}
561      * permission when invoked directly or indirectly by the constructor
562      * of a subclass which overrides the {@code getContextClassLoader}
563      * or {@code setContextClassLoader} methods.
564      *
565      * <p>The priority of the newly created thread is set equal to the
566      * priority of the thread creating it, that is, the currently running
567      * thread. The method {@linkplain #setPriority setPriority} may be
568      * used to change the priority to a new value.
569      *
570      * <p>The newly created thread is initially marked as being a daemon
571      * thread if and only if the thread creating it is currently marked
572      * as a daemon thread. The method {@linkplain #setDaemon setDaemon}
573      * may be used to change whether or not a thread is a daemon.
574      *
575      * @param  group
576      *         the thread group. If {@code null} and there is a security
577      *         manager, the group is determined by {@linkplain
578      *         SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
579      *         If there is not a security manager or {@code
580      *         SecurityManager.getThreadGroup()} returns {@code null}, the group
581      *         is set to the current thread's thread group.
582      *
583      * @param  target
584      *         the object whose {@code run} method is invoked when this thread
585      *         is started. If {@code null}, this thread's run method is invoked.
586      *
587      * @param  name
588      *         the name of the new thread
589      *
590      * @throws  SecurityException
591      *          if the current thread cannot create a thread in the specified
592      *          thread group or cannot override the context class loader methods.
593      */
594     public Thread(ThreadGroup group, Runnable target, String name) {
595         init(group, target, name, 0);
596     }
597 
598     /**
599      * Allocates a new {@code Thread} object so that it has {@code target}
600      * as its run object, has the specified {@code name} as its name,
601      * and belongs to the thread group referred to by {@code group}, and has
602      * the specified <i>stack size</i>.
603      *
604      * <p>This constructor is identical to {@link
605      * #Thread(ThreadGroup,Runnable,String)} with the exception of the fact
606      * that it allows the thread stack size to be specified.  The stack size
607      * is the approximate number of bytes of address space that the virtual
608      * machine is to allocate for this thread's stack.  <b>The effect of the
609      * {@code stackSize} parameter, if any, is highly platform dependent.</b>
610      *
611      * <p>On some platforms, specifying a higher value for the
612      * {@code stackSize} parameter may allow a thread to achieve greater
613      * recursion depth before throwing a {@link StackOverflowError}.
614      * Similarly, specifying a lower value may allow a greater number of
615      * threads to exist concurrently without throwing an {@link
616      * OutOfMemoryError} (or other internal error).  The details of
617      * the relationship between the value of the <tt>stackSize</tt> parameter
618      * and the maximum recursion depth and concurrency level are
619      * platform-dependent.  <b>On some platforms, the value of the
620      * {@code stackSize} parameter may have no effect whatsoever.</b>
621      *
622      * <p>The virtual machine is free to treat the {@code stackSize}
623      * parameter as a suggestion.  If the specified value is unreasonably low
624      * for the platform, the virtual machine may instead use some
625      * platform-specific minimum value; if the specified value is unreasonably
626      * high, the virtual machine may instead use some platform-specific
627      * maximum.  Likewise, the virtual machine is free to round the specified
628      * value up or down as it sees fit (or to ignore it completely).
629      *
630      * <p>Specifying a value of zero for the {@code stackSize} parameter will
631      * cause this constructor to behave exactly like the
632      * {@code Thread(ThreadGroup, Runnable, String)} constructor.
633      *
634      * <p><i>Due to the platform-dependent nature of the behavior of this
635      * constructor, extreme care should be exercised in its use.
636      * The thread stack size necessary to perform a given computation will
637      * likely vary from one JRE implementation to another.  In light of this
638      * variation, careful tuning of the stack size parameter may be required,
639      * and the tuning may need to be repeated for each JRE implementation on
640      * which an application is to run.</i>
641      *
642      * <p>Implementation note: Java platform implementers are encouraged to
643      * document their implementation's behavior with respect to the
644      * {@code stackSize} parameter.
645      *
646      *
647      * @param  group
648      *         the thread group. If {@code null} and there is a security
649      *         manager, the group is determined by {@linkplain
650      *         SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
651      *         If there is not a security manager or {@code
652      *         SecurityManager.getThreadGroup()} returns {@code null}, the group
653      *         is set to the current thread's thread group.
654      *
655      * @param  target
656      *         the object whose {@code run} method is invoked when this thread
657      *         is started. If {@code null}, this thread's run method is invoked.
658      *
659      * @param  name
660      *         the name of the new thread
661      *
662      * @param  stackSize
663      *         the desired stack size for the new thread, or zero to indicate
664      *         that this parameter is to be ignored.
665      *
666      * @throws  SecurityException
667      *          if the current thread cannot create a thread in the specified
668      *          thread group
669      *
670      * @since 1.4
671      */
672     public Thread(ThreadGroup group, Runnable target, String name,
673                   long stackSize) {
674         init(group, target, name, stackSize);
675     }
676 
677     /**
678      * Causes this thread to begin execution; the Java Virtual Machine
679      * calls the <code>run</code> method of this thread.
680      * <p>
681      * The result is that two threads are running concurrently: the
682      * current thread (which returns from the call to the
683      * <code>start</code> method) and the other thread (which executes its
684      * <code>run</code> method).
685      * <p>
686      * It is never legal to start a thread more than once.
687      * In particular, a thread may not be restarted once it has completed
688      * execution.
689      *
690      * @exception  IllegalThreadStateException  if the thread was already
691      *               started.
692      * @see        #run()
693      * @see        #stop()
694      */
695     public synchronized void start() {
696         /**
697          * This method is not invoked for the main method thread or "system"
698          * group threads created/set up by the VM. Any new functionality added
699          * to this method in the future may have to also be added to the VM.
700          *
701          * A zero status value corresponds to state "NEW".
702          */
703         if (threadStatus != 0)
704             throw new IllegalThreadStateException();
705 
706         /* Notify the group that this thread is about to be started
707          * so that it can be added to the group's list of threads
708          * and the group's unstarted count can be decremented. */
709         group.add(this);
710 
711         boolean started = false;
712         try {
713             start0();
714             started = true;
715         } finally {
716             try {
717                 if (!started) {
718                     group.threadStartFailed(this);
719                 }
720             } catch (Throwable ignore) {
721                 /* do nothing. If start0 threw a Throwable then
722                   it will be passed up the call stack */
723             }
724         }
725     }
726 
727     private native void start0();
728 
729     /**
730      * If this thread was constructed using a separate
731      * <code>Runnable</code> run object, then that
732      * <code>Runnable</code> object's <code>run</code> method is called;
733      * otherwise, this method does nothing and returns.
734      * <p>
735      * Subclasses of <code>Thread</code> should override this method.
736      *
737      * @see     #start()
738      * @see     #stop()
739      * @see     #Thread(ThreadGroup, Runnable, String)
740      */
741     @Override
742     public void run() {
743         if (target != null) {
744             target.run();
745         }
746     }
747 
748     /**
749      * This method is called by the system to give a Thread
750      * a chance to clean up before it actually exits.
751      */
752     private void exit() {
753         if (group != null) {
754             group.threadTerminated(this);
755             group = null;
756         }
757         /* Aggressively null out all reference fields: see bug 4006245 */
758         target = null;
759         /* Speed the release of some of these resources */
760         threadLocals = null;
761         inheritableThreadLocals = null;
762         inheritedAccessControlContext = null;
763         blocker = null;
764         uncaughtExceptionHandler = null;
765     }
766 
767     /**
768      * Forces the thread to stop executing.
769      * <p>
770      * If there is a security manager installed, its <code>checkAccess</code>
771      * method is called with <code>this</code>
772      * as its argument. This may result in a
773      * <code>SecurityException</code> being raised (in the current thread).
774      * <p>
775      * If this thread is different from the current thread (that is, the current
776      * thread is trying to stop a thread other than itself), the
777      * security manager's <code>checkPermission</code> method (with a
778      * <code>RuntimePermission("stopThread")</code> argument) is called in
779      * addition.
780      * Again, this may result in throwing a
781      * <code>SecurityException</code> (in the current thread).
782      * <p>
783      * The thread represented by this thread is forced to stop whatever
784      * it is doing abnormally and to throw a newly created
785      * <code>ThreadDeath</code> object as an exception.
786      * <p>
787      * It is permitted to stop a thread that has not yet been started.
788      * If the thread is eventually started, it immediately terminates.
789      * <p>
790      * An application should not normally try to catch
791      * <code>ThreadDeath</code> unless it must do some extraordinary
792      * cleanup operation (note that the throwing of
793      * <code>ThreadDeath</code> causes <code>finally</code> clauses of
794      * <code>try</code> statements to be executed before the thread
795      * officially dies).  If a <code>catch</code> clause catches a
796      * <code>ThreadDeath</code> object, it is important to rethrow the
797      * object so that the thread actually dies.
798      * <p>
799      * The top-level error handler that reacts to otherwise uncaught
800      * exceptions does not print out a message or otherwise notify the
801      * application if the uncaught exception is an instance of
802      * <code>ThreadDeath</code>.
803      *
804      * @exception  SecurityException  if the current thread cannot
805      *               modify this thread.
806      * @see        #interrupt()
807      * @see        #checkAccess()
808      * @see        #run()
809      * @see        #start()
810      * @see        ThreadDeath
811      * @see        ThreadGroup#uncaughtException(Thread,Throwable)
812      * @see        SecurityManager#checkAccess(Thread)
813      * @see        SecurityManager#checkPermission
814      * @deprecated This method is inherently unsafe.  Stopping a thread with
815      *       Thread.stop causes it to unlock all of the monitors that it
816      *       has locked (as a natural consequence of the unchecked
817      *       <code>ThreadDeath</code> exception propagating up the stack).  If
818      *       any of the objects previously protected by these monitors were in
819      *       an inconsistent state, the damaged objects become visible to
820      *       other threads, potentially resulting in arbitrary behavior.  Many
821      *       uses of <code>stop</code> should be replaced by code that simply
822      *       modifies some variable to indicate that the target thread should
823      *       stop running.  The target thread should check this variable
824      *       regularly, and return from its run method in an orderly fashion
825      *       if the variable indicates that it is to stop running.  If the
826      *       target thread waits for long periods (on a condition variable,
827      *       for example), the <code>interrupt</code> method should be used to
828      *       interrupt the wait.
829      *       For more information, see
830      *       <a href="{@docRoot}/../technotes/guides/concurrency/threadPrimitiveDeprecation.html">Why
831      *       are Thread.stop, Thread.suspend and Thread.resume Deprecated?</a>.
832      */
833     @Deprecated
834     public final void stop() {
835         SecurityManager security = System.getSecurityManager();
836         if (security != null) {
837             checkAccess();
838             if (this != Thread.currentThread()) {
839                 security.checkPermission(SecurityConstants.STOP_THREAD_PERMISSION);
840             }
841         }
842         // A zero status value corresponds to "NEW", it can't change to
843         // not-NEW because we hold the lock.
844         if (threadStatus != 0) {
845             resume(); // Wake up thread if it was suspended; no-op otherwise
846         }
847 
848         // The VM can handle all thread states
849         stop0(new ThreadDeath());
850     }
851 
852     /**
853      * Throws {@code UnsupportedOperationException}.
854      *
855      * @param obj ignored
856      *
857      * @deprecated This method was originally designed to force a thread to stop
858      *        and throw a given {@code Throwable} as an exception. It was
859      *        inherently unsafe (see {@link #stop()} for details), and furthermore
860      *        could be used to generate exceptions that the target thread was
861      *        not prepared to handle.
862      *        For more information, see
863      *        <a href="{@docRoot}/../technotes/guides/concurrency/threadPrimitiveDeprecation.html">Why
864      *        are Thread.stop, Thread.suspend and Thread.resume Deprecated?</a>.
865      */
866     @Deprecated
867     public final synchronized void stop(Throwable obj) {
868         throw new UnsupportedOperationException();
869     }
870 
871     /**
872      * Interrupts this thread.
873      *
874      * <p> Unless the current thread is interrupting itself, which is
875      * always permitted, the {@link #checkAccess() checkAccess} method
876      * of this thread is invoked, which may cause a {@link
877      * SecurityException} to be thrown.
878      *
879      * <p> If this thread is blocked in an invocation of the {@link
880      * Object#wait() wait()}, {@link Object#wait(long) wait(long)}, or {@link
881      * Object#wait(long, int) wait(long, int)} methods of the {@link Object}
882      * class, or of the {@link #join()}, {@link #join(long)}, {@link
883      * #join(long, int)}, {@link #sleep(long)}, or {@link #sleep(long, int)},
884      * methods of this class, then its interrupt status will be cleared and it
885      * will receive an {@link InterruptedException}.
886      *
887      * <p> If this thread is blocked in an I/O operation upon an {@link
888      * java.nio.channels.InterruptibleChannel InterruptibleChannel}
889      * then the channel will be closed, the thread's interrupt
890      * status will be set, and the thread will receive a {@link
891      * java.nio.channels.ClosedByInterruptException}.
892      *
893      * <p> If this thread is blocked in a {@link java.nio.channels.Selector}
894      * then the thread's interrupt status will be set and it will return
895      * immediately from the selection operation, possibly with a non-zero
896      * value, just as if the selector's {@link
897      * java.nio.channels.Selector#wakeup wakeup} method were invoked.
898      *
899      * <p> If none of the previous conditions hold then this thread's interrupt
900      * status will be set. </p>
901      *
902      * <p> Interrupting a thread that is not alive need not have any effect.
903      *
904      * @throws  SecurityException
905      *          if the current thread cannot modify this thread
906      *
907      * @revised 6.0
908      * @spec JSR-51
909      */
910     public void interrupt() {
911         if (this != Thread.currentThread())
912             checkAccess();
913 
914         synchronized (blockerLock) {
915             Interruptible b = blocker;
916             if (b != null) {
917                 interrupt0();           // Just to set the interrupt flag
918                 b.interrupt(this);
919                 return;
920             }
921         }
922         interrupt0();
923     }
924 
925     /**
926      * Tests whether the current thread has been interrupted.  The
927      * <i>interrupted status</i> of the thread is cleared by this method.  In
928      * other words, if this method were to be called twice in succession, the
929      * second call would return false (unless the current thread were
930      * interrupted again, after the first call had cleared its interrupted
931      * status and before the second call had examined it).
932      *
933      * <p>A thread interruption ignored because a thread was not alive
934      * at the time of the interrupt will be reflected by this method
935      * returning false.
936      *
937      * @return  <code>true</code> if the current thread has been interrupted;
938      *          <code>false</code> otherwise.
939      * @see #isInterrupted()
940      * @revised 6.0
941      */
942     public static boolean interrupted() {
943         return currentThread().isInterrupted(true);
944     }
945 
946     /**
947      * Tests whether this thread has been interrupted.  The <i>interrupted
948      * status</i> of the thread is unaffected by this method.
949      *
950      * <p>A thread interruption ignored because a thread was not alive
951      * at the time of the interrupt will be reflected by this method
952      * returning false.
953      *
954      * @return  <code>true</code> if this thread has been interrupted;
955      *          <code>false</code> otherwise.
956      * @see     #interrupted()
957      * @revised 6.0
958      */
959     public boolean isInterrupted() {
960         return isInterrupted(false);
961     }
962 
963     /**
964      * Tests if some Thread has been interrupted.  The interrupted state
965      * is reset or not based on the value of ClearInterrupted that is
966      * passed.
967      */
968     private native boolean isInterrupted(boolean ClearInterrupted);
969 
970     /**
971      * Throws {@link NoSuchMethodError}.
972      *
973      * @deprecated This method was originally designed to destroy this
974      *     thread without any cleanup. Any monitors it held would have
975      *     remained locked. However, the method was never implemented.
976      *     If if were to be implemented, it would be deadlock-prone in
977      *     much the manner of {@link #suspend}. If the target thread held
978      *     a lock protecting a critical system resource when it was
979      *     destroyed, no thread could ever access this resource again.
980      *     If another thread ever attempted to lock this resource, deadlock
981      *     would result. Such deadlocks typically manifest themselves as
982      *     "frozen" processes. For more information, see
983      *     <a href="{@docRoot}/../technotes/guides/concurrency/threadPrimitiveDeprecation.html">
984      *     Why are Thread.stop, Thread.suspend and Thread.resume Deprecated?</a>.
985      * @throws NoSuchMethodError always
986      */
987     @Deprecated
988     public void destroy() {
989         throw new NoSuchMethodError();
990     }
991 
992     /**
993      * Tests if this thread is alive. A thread is alive if it has
994      * been started and has not yet died.
995      *
996      * @return  <code>true</code> if this thread is alive;
997      *          <code>false</code> otherwise.
998      */
999     public final native boolean isAlive();
1000 
1001     /**
1002      * Suspends this thread.
1003      * <p>
1004      * First, the <code>checkAccess</code> method of this thread is called
1005      * with no arguments. This may result in throwing a
1006      * <code>SecurityException </code>(in the current thread).
1007      * <p>
1008      * If the thread is alive, it is suspended and makes no further
1009      * progress unless and until it is resumed.
1010      *
1011      * @exception  SecurityException  if the current thread cannot modify
1012      *               this thread.
1013      * @see #checkAccess
1014      * @deprecated   This method has been deprecated, as it is
1015      *   inherently deadlock-prone.  If the target thread holds a lock on the
1016      *   monitor protecting a critical system resource when it is suspended, no
1017      *   thread can access this resource until the target thread is resumed. If
1018      *   the thread that would resume the target thread attempts to lock this
1019      *   monitor prior to calling <code>resume</code>, deadlock results.  Such
1020      *   deadlocks typically manifest themselves as "frozen" processes.
1021      *   For more information, see
1022      *   <a href="{@docRoot}/../technotes/guides/concurrency/threadPrimitiveDeprecation.html">Why
1023      *   are Thread.stop, Thread.suspend and Thread.resume Deprecated?</a>.
1024      */
1025     @Deprecated
1026     public final void suspend() {
1027         checkAccess();
1028         suspend0();
1029     }
1030 
1031     /**
1032      * Resumes a suspended thread.
1033      * <p>
1034      * First, the <code>checkAccess</code> method of this thread is called
1035      * with no arguments. This may result in throwing a
1036      * <code>SecurityException</code> (in the current thread).
1037      * <p>
1038      * If the thread is alive but suspended, it is resumed and is
1039      * permitted to make progress in its execution.
1040      *
1041      * @exception  SecurityException  if the current thread cannot modify this
1042      *               thread.
1043      * @see        #checkAccess
1044      * @see        #suspend()
1045      * @deprecated This method exists solely for use with {@link #suspend},
1046      *     which has been deprecated because it is deadlock-prone.
1047      *     For more information, see
1048      *     <a href="{@docRoot}/../technotes/guides/concurrency/threadPrimitiveDeprecation.html">Why
1049      *     are Thread.stop, Thread.suspend and Thread.resume Deprecated?</a>.
1050      */
1051     @Deprecated
1052     public final void resume() {
1053         checkAccess();
1054         resume0();
1055     }
1056 
1057     /**
1058      * Changes the priority of this thread.
1059      * <p>
1060      * First the <code>checkAccess</code> method of this thread is called
1061      * with no arguments. This may result in throwing a
1062      * <code>SecurityException</code>.
1063      * <p>
1064      * Otherwise, the priority of this thread is set to the smaller of
1065      * the specified <code>newPriority</code> and the maximum permitted
1066      * priority of the thread's thread group.
1067      *
1068      * @param newPriority priority to set this thread to
1069      * @exception  IllegalArgumentException  If the priority is not in the
1070      *               range <code>MIN_PRIORITY</code> to
1071      *               <code>MAX_PRIORITY</code>.
1072      * @exception  SecurityException  if the current thread cannot modify
1073      *               this thread.
1074      * @see        #getPriority
1075      * @see        #checkAccess()
1076      * @see        #getThreadGroup()
1077      * @see        #MAX_PRIORITY
1078      * @see        #MIN_PRIORITY
1079      * @see        ThreadGroup#getMaxPriority()
1080      */
1081     public final void setPriority(int newPriority) {
1082         ThreadGroup g;
1083         checkAccess();
1084         if (newPriority > MAX_PRIORITY || newPriority < MIN_PRIORITY) {
1085             throw new IllegalArgumentException();
1086         }
1087         if((g = getThreadGroup()) != null) {
1088             if (newPriority > g.getMaxPriority()) {
1089                 newPriority = g.getMaxPriority();
1090             }
1091             setPriority0(priority = newPriority);
1092         }
1093     }
1094 
1095     /**
1096      * Returns this thread's priority.
1097      *
1098      * @return  this thread's priority.
1099      * @see     #setPriority
1100      */
1101     public final int getPriority() {
1102         return priority;
1103     }
1104 
1105     /**
1106      * Changes the name of this thread to be equal to the argument
1107      * <code>name</code>.
1108      * <p>
1109      * First the <code>checkAccess</code> method of this thread is called
1110      * with no arguments. This may result in throwing a
1111      * <code>SecurityException</code>.
1112      *
1113      * @param      name   the new name for this thread.
1114      * @exception  SecurityException  if the current thread cannot modify this
1115      *               thread.
1116      * @see        #getName
1117      * @see        #checkAccess()
1118      */
1119     public final synchronized void setName(String name) {
1120         checkAccess();
1121         this.name = name.toCharArray();
1122         if (threadStatus != 0) {
1123             setNativeName(name);
1124         }
1125     }
1126 
1127     /**
1128      * Returns this thread's name.
1129      *
1130      * @return  this thread's name.
1131      * @see     #setName(String)
1132      */
1133     public final String getName() {
1134         return new String(name, true);
1135     }
1136 
1137     /**
1138      * Returns the thread group to which this thread belongs.
1139      * This method returns null if this thread has died
1140      * (been stopped).
1141      *
1142      * @return  this thread's thread group.
1143      */
1144     public final ThreadGroup getThreadGroup() {
1145         return group;
1146     }
1147 
1148     /**
1149      * Returns an estimate of the number of active threads in the current
1150      * thread's {@linkplain java.lang.ThreadGroup thread group} and its
1151      * subgroups. Recursively iterates over all subgroups in the current
1152      * thread's thread group.
1153      *
1154      * <p> The value returned is only an estimate because the number of
1155      * threads may change dynamically while this method traverses internal
1156      * data structures, and might be affected by the presence of certain
1157      * system threads. This method is intended primarily for debugging
1158      * and monitoring purposes.
1159      *
1160      * @return  an estimate of the number of active threads in the current
1161      *          thread's thread group and in any other thread group that
1162      *          has the current thread's thread group as an ancestor
1163      */
1164     public static int activeCount() {
1165         return currentThread().getThreadGroup().activeCount();
1166     }
1167 
1168     /**
1169      * Copies into the specified array every active thread in the current
1170      * thread's thread group and its subgroups. This method simply
1171      * invokes the {@link java.lang.ThreadGroup#enumerate(Thread[])}
1172      * method of the current thread's thread group.
1173      *
1174      * <p> An application might use the {@linkplain #activeCount activeCount}
1175      * method to get an estimate of how big the array should be, however
1176      * <i>if the array is too short to hold all the threads, the extra threads
1177      * are silently ignored.</i>  If it is critical to obtain every active
1178      * thread in the current thread's thread group and its subgroups, the
1179      * invoker should verify that the returned int value is strictly less
1180      * than the length of {@code tarray}.
1181      *
1182      * <p> Due to the inherent race condition in this method, it is recommended
1183      * that the method only be used for debugging and monitoring purposes.
1184      *
1185      * @param  tarray
1186      *         an array into which to put the list of threads
1187      *
1188      * @return  the number of threads put into the array
1189      *
1190      * @throws  SecurityException
1191      *          if {@link java.lang.ThreadGroup#checkAccess} determines that
1192      *          the current thread cannot access its thread group
1193      */
1194     public static int enumerate(Thread tarray[]) {
1195         return currentThread().getThreadGroup().enumerate(tarray);
1196     }
1197 
1198     /**
1199      * Counts the number of stack frames in this thread. The thread must
1200      * be suspended.
1201      *
1202      * @return     the number of stack frames in this thread.
1203      * @exception  IllegalThreadStateException  if this thread is not
1204      *             suspended.
1205      * @deprecated The definition of this call depends on {@link #suspend},
1206      *             which is deprecated.  Further, the results of this call
1207      *             were never well-defined.
1208      */
1209     @Deprecated
1210     public native int countStackFrames();
1211 
1212     /**
1213      * Waits at most {@code millis} milliseconds for this thread to
1214      * die. A timeout of {@code 0} means to wait forever.
1215      *
1216      * <p> This implementation uses a loop of {@code this.wait} calls
1217      * conditioned on {@code this.isAlive}. As a thread terminates the
1218      * {@code this.notifyAll} method is invoked. It is recommended that
1219      * applications not use {@code wait}, {@code notify}, or
1220      * {@code notifyAll} on {@code Thread} instances.
1221      *
1222      * @param  millis
1223      *         the time to wait in milliseconds
1224      *
1225      * @throws  IllegalArgumentException
1226      *          if the value of {@code millis} is negative
1227      *
1228      * @throws  InterruptedException
1229      *          if any thread has interrupted the current thread. The
1230      *          <i>interrupted status</i> of the current thread is
1231      *          cleared when this exception is thrown.
1232      */
1233     public final synchronized void join(long millis)
1234     throws InterruptedException {
1235         long base = System.currentTimeMillis();
1236         long now = 0;
1237 
1238         if (millis < 0) {
1239             throw new IllegalArgumentException("timeout value is negative");
1240         }
1241 
1242         if (millis == 0) {
1243             while (isAlive()) {
1244                 wait(0);
1245             }
1246         } else {
1247             while (isAlive()) {
1248                 long delay = millis - now;
1249                 if (delay <= 0) {
1250                     break;
1251                 }
1252                 wait(delay);
1253                 now = System.currentTimeMillis() - base;
1254             }
1255         }
1256     }
1257 
1258     /**
1259      * Waits at most {@code millis} milliseconds plus
1260      * {@code nanos} nanoseconds for this thread to die.
1261      *
1262      * <p> This implementation uses a loop of {@code this.wait} calls
1263      * conditioned on {@code this.isAlive}. As a thread terminates the
1264      * {@code this.notifyAll} method is invoked. It is recommended that
1265      * applications not use {@code wait}, {@code notify}, or
1266      * {@code notifyAll} on {@code Thread} instances.
1267      *
1268      * @param  millis
1269      *         the time to wait in milliseconds
1270      *
1271      * @param  nanos
1272      *         {@code 0-999999} additional nanoseconds to wait
1273      *
1274      * @throws  IllegalArgumentException
1275      *          if the value of {@code millis} is negative, or the value
1276      *          of {@code nanos} is not in the range {@code 0-999999}
1277      *
1278      * @throws  InterruptedException
1279      *          if any thread has interrupted the current thread. The
1280      *          <i>interrupted status</i> of the current thread is
1281      *          cleared when this exception is thrown.
1282      */
1283     public final synchronized void join(long millis, int nanos)
1284     throws InterruptedException {
1285 
1286         if (millis < 0) {
1287             throw new IllegalArgumentException("timeout value is negative");
1288         }
1289 
1290         if (nanos < 0 || nanos > 999999) {
1291             throw new IllegalArgumentException(
1292                                 "nanosecond timeout value out of range");
1293         }
1294 
1295         if (nanos >= 500000 || (nanos != 0 && millis == 0)) {
1296             millis++;
1297         }
1298 
1299         join(millis);
1300     }
1301 
1302     /**
1303      * Waits for this thread to die.
1304      *
1305      * <p> An invocation of this method behaves in exactly the same
1306      * way as the invocation
1307      *
1308      * <blockquote>
1309      * {@linkplain #join(long) join}{@code (0)}
1310      * </blockquote>
1311      *
1312      * @throws  InterruptedException
1313      *          if any thread has interrupted the current thread. The
1314      *          <i>interrupted status</i> of the current thread is
1315      *          cleared when this exception is thrown.
1316      */
1317     public final void join() throws InterruptedException {
1318         join(0);
1319     }
1320 
1321     /**
1322      * Prints a stack trace of the current thread to the standard error stream.
1323      * This method is used only for debugging.
1324      *
1325      * @see     Throwable#printStackTrace()
1326      */
1327     public static void dumpStack() {
1328         new Exception("Stack trace").printStackTrace();
1329     }
1330 
1331     /**
1332      * Marks this thread as either a {@linkplain #isDaemon daemon} thread
1333      * or a user thread. The Java Virtual Machine exits when the only
1334      * threads running are all daemon threads.
1335      *
1336      * <p> This method must be invoked before the thread is started.
1337      *
1338      * @param  on
1339      *         if {@code true}, marks this thread as a daemon thread
1340      *
1341      * @throws  IllegalThreadStateException
1342      *          if this thread is {@linkplain #isAlive alive}
1343      *
1344      * @throws  SecurityException
1345      *          if {@link #checkAccess} determines that the current
1346      *          thread cannot modify this thread
1347      */
1348     public final void setDaemon(boolean on) {
1349         checkAccess();
1350         if (isAlive()) {
1351             throw new IllegalThreadStateException();
1352         }
1353         daemon = on;
1354     }
1355 
1356     /**
1357      * Tests if this thread is a daemon thread.
1358      *
1359      * @return  <code>true</code> if this thread is a daemon thread;
1360      *          <code>false</code> otherwise.
1361      * @see     #setDaemon(boolean)
1362      */
1363     public final boolean isDaemon() {
1364         return daemon;
1365     }
1366 
1367     /**
1368      * Determines if the currently running thread has permission to
1369      * modify this thread.
1370      * <p>
1371      * If there is a security manager, its <code>checkAccess</code> method
1372      * is called with this thread as its argument. This may result in
1373      * throwing a <code>SecurityException</code>.
1374      *
1375      * @exception  SecurityException  if the current thread is not allowed to
1376      *               access this thread.
1377      * @see        SecurityManager#checkAccess(Thread)
1378      */
1379     public final void checkAccess() {
1380         SecurityManager security = System.getSecurityManager();
1381         if (security != null) {
1382             security.checkAccess(this);
1383         }
1384     }
1385 
1386     /**
1387      * Returns a string representation of this thread, including the
1388      * thread's name, priority, and thread group.
1389      *
1390      * @return  a string representation of this thread.
1391      */
1392     public String toString() {
1393         ThreadGroup group = getThreadGroup();
1394         if (group != null) {
1395             return "Thread[" + getName() + "," + getPriority() + "," +
1396                            group.getName() + "]";
1397         } else {
1398             return "Thread[" + getName() + "," + getPriority() + "," +
1399                             "" + "]";
1400         }
1401     }
1402 
1403     /**
1404      * Returns the context ClassLoader for this Thread. The context
1405      * ClassLoader is provided by the creator of the thread for use
1406      * by code running in this thread when loading classes and resources.
1407      * If not {@linkplain #setContextClassLoader set}, the default is the
1408      * ClassLoader context of the parent Thread. The context ClassLoader of the
1409      * primordial thread is typically set to the class loader used to load the
1410      * application.
1411      *
1412      * <p>If a security manager is present, and the invoker's class loader is not
1413      * {@code null} and is not the same as or an ancestor of the context class
1414      * loader, then this method invokes the security manager's {@link
1415      * SecurityManager#checkPermission(java.security.Permission) checkPermission}
1416      * method with a {@link RuntimePermission RuntimePermission}{@code
1417      * ("getClassLoader")} permission to verify that retrieval of the context
1418      * class loader is permitted.
1419      *
1420      * @return  the context ClassLoader for this Thread, or {@code null}
1421      *          indicating the system class loader (or, failing that, the
1422      *          bootstrap class loader)
1423      *
1424      * @throws  SecurityException
1425      *          if the current thread cannot get the context ClassLoader
1426      *
1427      * @since 1.2
1428      */
1429     @CallerSensitive
1430     public ClassLoader getContextClassLoader() {
1431         if (contextClassLoader == null)
1432             return null;
1433         SecurityManager sm = System.getSecurityManager();
1434         if (sm != null) {
1435             ClassLoader.checkClassLoaderPermission(contextClassLoader,
1436                                                    Reflection.getCallerClass());
1437         }
1438         return contextClassLoader;
1439     }
1440 
1441     /**
1442      * Sets the context ClassLoader for this Thread. The context
1443      * ClassLoader can be set when a thread is created, and allows
1444      * the creator of the thread to provide the appropriate class loader,
1445      * through {@code getContextClassLoader}, to code running in the thread
1446      * when loading classes and resources.
1447      *
1448      * <p>If a security manager is present, its {@link
1449      * SecurityManager#checkPermission(java.security.Permission) checkPermission}
1450      * method is invoked with a {@link RuntimePermission RuntimePermission}{@code
1451      * ("setContextClassLoader")} permission to see if setting the context
1452      * ClassLoader is permitted.
1453      *
1454      * @param  cl
1455      *         the context ClassLoader for this Thread, or null  indicating the
1456      *         system class loader (or, failing that, the bootstrap class loader)
1457      *
1458      * @throws  SecurityException
1459      *          if the current thread cannot set the context ClassLoader
1460      *
1461      * @since 1.2
1462      */
1463     public void setContextClassLoader(ClassLoader cl) {
1464         SecurityManager sm = System.getSecurityManager();
1465         if (sm != null) {
1466             sm.checkPermission(new RuntimePermission("setContextClassLoader"));
1467         }
1468         contextClassLoader = cl;
1469     }
1470 
1471     /**
1472      * Returns <tt>true</tt> if and only if the current thread holds the
1473      * monitor lock on the specified object.
1474      *
1475      * <p>This method is designed to allow a program to assert that
1476      * the current thread already holds a specified lock:
1477      * <pre>
1478      *     assert Thread.holdsLock(obj);
1479      * </pre>
1480      *
1481      * @param  obj the object on which to test lock ownership
1482      * @throws NullPointerException if obj is <tt>null</tt>
1483      * @return <tt>true</tt> if the current thread holds the monitor lock on
1484      *         the specified object.
1485      * @since 1.4
1486      */
1487     public static native boolean holdsLock(Object obj);
1488 
1489     private static final StackTraceElement[] EMPTY_STACK_TRACE
1490         = new StackTraceElement[0];
1491 
1492     /**
1493      * Returns an array of stack trace elements representing the stack dump
1494      * of this thread.  This method will return a zero-length array if
1495      * this thread has not started, has started but has not yet been
1496      * scheduled to run by the system, or has terminated.
1497      * If the returned array is of non-zero length then the first element of
1498      * the array represents the top of the stack, which is the most recent
1499      * method invocation in the sequence.  The last element of the array
1500      * represents the bottom of the stack, which is the least recent method
1501      * invocation in the sequence.
1502      *
1503      * <p>If there is a security manager, and this thread is not
1504      * the current thread, then the security manager's
1505      * <tt>checkPermission</tt> method is called with a
1506      * <tt>RuntimePermission("getStackTrace")</tt> permission
1507      * to see if it's ok to get the stack trace.
1508      *
1509      * <p>Some virtual machines may, under some circumstances, omit one
1510      * or more stack frames from the stack trace.  In the extreme case,
1511      * a virtual machine that has no stack trace information concerning
1512      * this thread is permitted to return a zero-length array from this
1513      * method.
1514      *
1515      * @return an array of <tt>StackTraceElement</tt>,
1516      * each represents one stack frame.
1517      *
1518      * @throws SecurityException
1519      *        if a security manager exists and its
1520      *        <tt>checkPermission</tt> method doesn't allow
1521      *        getting the stack trace of thread.
1522      * @see SecurityManager#checkPermission
1523      * @see RuntimePermission
1524      * @see Throwable#getStackTrace
1525      *
1526      * @since 1.5
1527      */
1528     public StackTraceElement[] getStackTrace() {
1529         if (this != Thread.currentThread()) {
1530             // check for getStackTrace permission
1531             SecurityManager security = System.getSecurityManager();
1532             if (security != null) {
1533                 security.checkPermission(
1534                     SecurityConstants.GET_STACK_TRACE_PERMISSION);
1535             }
1536             // optimization so we do not call into the vm for threads that
1537             // have not yet started or have terminated
1538             if (!isAlive()) {
1539                 return EMPTY_STACK_TRACE;
1540             }
1541             StackTraceElement[][] stackTraceArray = dumpThreads(new Thread[] {this});
1542             StackTraceElement[] stackTrace = stackTraceArray[0];
1543             // a thread that was alive during the previous isAlive call may have
1544             // since terminated, therefore not having a stacktrace.
1545             if (stackTrace == null) {
1546                 stackTrace = EMPTY_STACK_TRACE;
1547             }
1548             return stackTrace;
1549         } else {
1550             // Don't need JVM help for current thread
1551             return (new Exception()).getStackTrace();
1552         }
1553     }
1554 
1555     /**
1556      * Returns a map of stack traces for all live threads.
1557      * The map keys are threads and each map value is an array of
1558      * <tt>StackTraceElement</tt> that represents the stack dump
1559      * of the corresponding <tt>Thread</tt>.
1560      * The returned stack traces are in the format specified for
1561      * the {@link #getStackTrace getStackTrace} method.
1562      *
1563      * <p>The threads may be executing while this method is called.
1564      * The stack trace of each thread only represents a snapshot and
1565      * each stack trace may be obtained at different time.  A zero-length
1566      * array will be returned in the map value if the virtual machine has
1567      * no stack trace information about a thread.
1568      *
1569      * <p>If there is a security manager, then the security manager's
1570      * <tt>checkPermission</tt> method is called with a
1571      * <tt>RuntimePermission("getStackTrace")</tt> permission as well as
1572      * <tt>RuntimePermission("modifyThreadGroup")</tt> permission
1573      * to see if it is ok to get the stack trace of all threads.
1574      *
1575      * @return a <tt>Map</tt> from <tt>Thread</tt> to an array of
1576      * <tt>StackTraceElement</tt> that represents the stack trace of
1577      * the corresponding thread.
1578      *
1579      * @throws SecurityException
1580      *        if a security manager exists and its
1581      *        <tt>checkPermission</tt> method doesn't allow
1582      *        getting the stack trace of thread.
1583      * @see #getStackTrace
1584      * @see SecurityManager#checkPermission
1585      * @see RuntimePermission
1586      * @see Throwable#getStackTrace
1587      *
1588      * @since 1.5
1589      */
1590     public static Map<Thread, StackTraceElement[]> getAllStackTraces() {
1591         // check for getStackTrace permission
1592         SecurityManager security = System.getSecurityManager();
1593         if (security != null) {
1594             security.checkPermission(
1595                 SecurityConstants.GET_STACK_TRACE_PERMISSION);
1596             security.checkPermission(
1597                 SecurityConstants.MODIFY_THREADGROUP_PERMISSION);
1598         }
1599 
1600         // Get a snapshot of the list of all threads
1601         Thread[] threads = getThreads();
1602         StackTraceElement[][] traces = dumpThreads(threads);
1603         Map<Thread, StackTraceElement[]> m = new HashMap<>(threads.length);
1604         for (int i = 0; i < threads.length; i++) {
1605             StackTraceElement[] stackTrace = traces[i];
1606             if (stackTrace != null) {
1607                 m.put(threads[i], stackTrace);
1608             }
1609             // else terminated so we don't put it in the map
1610         }
1611         return m;
1612     }
1613 
1614 
1615     private static final RuntimePermission SUBCLASS_IMPLEMENTATION_PERMISSION =
1616                     new RuntimePermission("enableContextClassLoaderOverride");
1617 
1618     /** cache of subclass security audit results */
1619     /* Replace with ConcurrentReferenceHashMap when/if it appears in a future
1620      * release */
1621     private static class Caches {
1622         /** cache of subclass security audit results */
1623         static final ConcurrentMap<WeakClassKey,Boolean> subclassAudits =
1624             new ConcurrentHashMap<>();
1625 
1626         /** queue for WeakReferences to audited subclasses */
1627         static final ReferenceQueue<Class<?>> subclassAuditsQueue =
1628             new ReferenceQueue<>();
1629     }
1630 
1631     /**
1632      * Verifies that this (possibly subclass) instance can be constructed
1633      * without violating security constraints: the subclass must not override
1634      * security-sensitive non-final methods, or else the
1635      * "enableContextClassLoaderOverride" RuntimePermission is checked.
1636      */
1637     private static boolean isCCLOverridden(Class<?> cl) {
1638         if (cl == Thread.class)
1639             return false;
1640 
1641         processQueue(Caches.subclassAuditsQueue, Caches.subclassAudits);
1642         WeakClassKey key = new WeakClassKey(cl, Caches.subclassAuditsQueue);
1643         Boolean result = Caches.subclassAudits.get(key);
1644         if (result == null) {
1645             result = Boolean.valueOf(auditSubclass(cl));
1646             Caches.subclassAudits.putIfAbsent(key, result);
1647         }
1648 
1649         return result.booleanValue();
1650     }
1651 
1652     /**
1653      * Performs reflective checks on given subclass to verify that it doesn't
1654      * override security-sensitive non-final methods.  Returns true if the
1655      * subclass overrides any of the methods, false otherwise.
1656      */
1657     private static boolean auditSubclass(final Class<?> subcl) {
1658         Boolean result = AccessController.doPrivileged(
1659             new PrivilegedAction<Boolean>() {
1660                 public Boolean run() {
1661                     for (Class<?> cl = subcl;
1662                          cl != Thread.class;
1663                          cl = cl.getSuperclass())
1664                     {
1665                         try {
1666                             cl.getDeclaredMethod("getContextClassLoader", new Class<?>[0]);
1667                             return Boolean.TRUE;
1668                         } catch (NoSuchMethodException ex) {
1669                         }
1670                         try {
1671                             Class<?>[] params = {ClassLoader.class};
1672                             cl.getDeclaredMethod("setContextClassLoader", params);
1673                             return Boolean.TRUE;
1674                         } catch (NoSuchMethodException ex) {
1675                         }
1676                     }
1677                     return Boolean.FALSE;
1678                 }
1679             }
1680         );
1681         return result.booleanValue();
1682     }
1683 
1684     private native static StackTraceElement[][] dumpThreads(Thread[] threads);
1685     private native static Thread[] getThreads();
1686 
1687     /**
1688      * Returns the identifier of this Thread.  The thread ID is a positive
1689      * <tt>long</tt> number generated when this thread was created.
1690      * The thread ID is unique and remains unchanged during its lifetime.
1691      * When a thread is terminated, this thread ID may be reused.
1692      *
1693      * @return this thread's ID.
1694      * @since 1.5
1695      */
1696     public long getId() {
1697         return tid;
1698     }
1699 
1700     /**
1701      * A thread state.  A thread can be in one of the following states:
1702      * <ul>
1703      * <li>{@link #NEW}<br>
1704      *     A thread that has not yet started is in this state.
1705      *     </li>
1706      * <li>{@link #RUNNABLE}<br>
1707      *     A thread executing in the Java virtual machine is in this state.
1708      *     </li>
1709      * <li>{@link #BLOCKED}<br>
1710      *     A thread that is blocked waiting for a monitor lock
1711      *     is in this state.
1712      *     </li>
1713      * <li>{@link #WAITING}<br>
1714      *     A thread that is waiting indefinitely for another thread to
1715      *     perform a particular action is in this state.
1716      *     </li>
1717      * <li>{@link #TIMED_WAITING}<br>
1718      *     A thread that is waiting for another thread to perform an action
1719      *     for up to a specified waiting time is in this state.
1720      *     </li>
1721      * <li>{@link #TERMINATED}<br>
1722      *     A thread that has exited is in this state.
1723      *     </li>
1724      * </ul>
1725      *
1726      * <p>
1727      * A thread can be in only one state at a given point in time.
1728      * These states are virtual machine states which do not reflect
1729      * any operating system thread states.
1730      *
1731      * @since   1.5
1732      * @see #getState
1733      */
1734     public enum State {
1735         /**
1736          * Thread state for a thread which has not yet started.
1737          */
1738         NEW,
1739 
1740         /**
1741          * Thread state for a runnable thread.  A thread in the runnable
1742          * state is executing in the Java virtual machine but it may
1743          * be waiting for other resources from the operating system
1744          * such as processor.
1745          */
1746         RUNNABLE,
1747 
1748         /**
1749          * Thread state for a thread blocked waiting for a monitor lock.
1750          * A thread in the blocked state is waiting for a monitor lock
1751          * to enter a synchronized block/method or
1752          * reenter a synchronized block/method after calling
1753          * {@link Object#wait() Object.wait}.
1754          */
1755         BLOCKED,
1756 
1757         /**
1758          * Thread state for a waiting thread.
1759          * A thread is in the waiting state due to calling one of the
1760          * following methods:
1761          * <ul>
1762          *   <li>{@link Object#wait() Object.wait} with no timeout</li>
1763          *   <li>{@link #join() Thread.join} with no timeout</li>
1764          *   <li>{@link LockSupport#park() LockSupport.park}</li>
1765          * </ul>
1766          *
1767          * <p>A thread in the waiting state is waiting for another thread to
1768          * perform a particular action.
1769          *
1770          * For example, a thread that has called <tt>Object.wait()</tt>
1771          * on an object is waiting for another thread to call
1772          * <tt>Object.notify()</tt> or <tt>Object.notifyAll()</tt> on
1773          * that object. A thread that has called <tt>Thread.join()</tt>
1774          * is waiting for a specified thread to terminate.
1775          */
1776         WAITING,
1777 
1778         /**
1779          * Thread state for a waiting thread with a specified waiting time.
1780          * A thread is in the timed waiting state due to calling one of
1781          * the following methods with a specified positive waiting time:
1782          * <ul>
1783          *   <li>{@link #sleep Thread.sleep}</li>
1784          *   <li>{@link Object#wait(long) Object.wait} with timeout</li>
1785          *   <li>{@link #join(long) Thread.join} with timeout</li>
1786          *   <li>{@link LockSupport#parkNanos LockSupport.parkNanos}</li>
1787          *   <li>{@link LockSupport#parkUntil LockSupport.parkUntil}</li>
1788          * </ul>
1789          */
1790         TIMED_WAITING,
1791 
1792         /**
1793          * Thread state for a terminated thread.
1794          * The thread has completed execution.
1795          */
1796         TERMINATED;
1797     }
1798 
1799     /**
1800      * Returns the state of this thread.
1801      * This method is designed for use in monitoring of the system state,
1802      * not for synchronization control.
1803      *
1804      * @return this thread's state.
1805      * @since 1.5
1806      */
1807     public State getState() {
1808         // get current thread state
1809         return sun.misc.VM.toThreadState(threadStatus);
1810     }
1811 
1812     // Added in JSR-166
1813 
1814     /**
1815      * Interface for handlers invoked when a <tt>Thread</tt> abruptly
1816      * terminates due to an uncaught exception.
1817      * <p>When a thread is about to terminate due to an uncaught exception
1818      * the Java Virtual Machine will query the thread for its
1819      * <tt>UncaughtExceptionHandler</tt> using
1820      * {@link #getUncaughtExceptionHandler} and will invoke the handler's
1821      * <tt>uncaughtException</tt> method, passing the thread and the
1822      * exception as arguments.
1823      * If a thread has not had its <tt>UncaughtExceptionHandler</tt>
1824      * explicitly set, then its <tt>ThreadGroup</tt> object acts as its
1825      * <tt>UncaughtExceptionHandler</tt>. If the <tt>ThreadGroup</tt> object
1826      * has no
1827      * special requirements for dealing with the exception, it can forward
1828      * the invocation to the {@linkplain #getDefaultUncaughtExceptionHandler
1829      * default uncaught exception handler}.
1830      *
1831      * @see #setDefaultUncaughtExceptionHandler
1832      * @see #setUncaughtExceptionHandler
1833      * @see ThreadGroup#uncaughtException
1834      * @since 1.5
1835      */
1836     @FunctionalInterface
1837     public interface UncaughtExceptionHandler {
1838         /**
1839          * Method invoked when the given thread terminates due to the
1840          * given uncaught exception.
1841          * <p>Any exception thrown by this method will be ignored by the
1842          * Java Virtual Machine.
1843          * @param t the thread
1844          * @param e the exception
1845          */
1846         void uncaughtException(Thread t, Throwable e);
1847     }
1848 
1849     // null unless explicitly set
1850     private volatile UncaughtExceptionHandler uncaughtExceptionHandler;
1851 
1852     // null unless explicitly set
1853     private static volatile UncaughtExceptionHandler defaultUncaughtExceptionHandler;
1854 
1855     /**
1856      * Set the default handler invoked when a thread abruptly terminates
1857      * due to an uncaught exception, and no other handler has been defined
1858      * for that thread.
1859      *
1860      * <p>Uncaught exception handling is controlled first by the thread, then
1861      * by the thread's {@link ThreadGroup} object and finally by the default
1862      * uncaught exception handler. If the thread does not have an explicit
1863      * uncaught exception handler set, and the thread's thread group
1864      * (including parent thread groups)  does not specialize its
1865      * <tt>uncaughtException</tt> method, then the default handler's
1866      * <tt>uncaughtException</tt> method will be invoked.
1867      * <p>By setting the default uncaught exception handler, an application
1868      * can change the way in which uncaught exceptions are handled (such as
1869      * logging to a specific device, or file) for those threads that would
1870      * already accept whatever &quot;default&quot; behavior the system
1871      * provided.
1872      *
1873      * <p>Note that the default uncaught exception handler should not usually
1874      * defer to the thread's <tt>ThreadGroup</tt> object, as that could cause
1875      * infinite recursion.
1876      *
1877      * @param eh the object to use as the default uncaught exception handler.
1878      * If <tt>null</tt> then there is no default handler.
1879      *
1880      * @throws SecurityException if a security manager is present and it
1881      *         denies <tt>{@link RuntimePermission}
1882      *         (&quot;setDefaultUncaughtExceptionHandler&quot;)</tt>
1883      *
1884      * @see #setUncaughtExceptionHandler
1885      * @see #getUncaughtExceptionHandler
1886      * @see ThreadGroup#uncaughtException
1887      * @since 1.5
1888      */
1889     public static void setDefaultUncaughtExceptionHandler(UncaughtExceptionHandler eh) {
1890         SecurityManager sm = System.getSecurityManager();
1891         if (sm != null) {
1892             sm.checkPermission(
1893                 new RuntimePermission("setDefaultUncaughtExceptionHandler")
1894                     );
1895         }
1896 
1897          defaultUncaughtExceptionHandler = eh;
1898      }
1899 
1900     /**
1901      * Returns the default handler invoked when a thread abruptly terminates
1902      * due to an uncaught exception. If the returned value is <tt>null</tt>,
1903      * there is no default.
1904      * @since 1.5
1905      * @see #setDefaultUncaughtExceptionHandler
1906      * @return the default uncaught exception handler for all threads
1907      */
1908     public static UncaughtExceptionHandler getDefaultUncaughtExceptionHandler(){
1909         return defaultUncaughtExceptionHandler;
1910     }
1911 
1912     /**
1913      * Returns the handler invoked when this thread abruptly terminates
1914      * due to an uncaught exception. If this thread has not had an
1915      * uncaught exception handler explicitly set then this thread's
1916      * <tt>ThreadGroup</tt> object is returned, unless this thread
1917      * has terminated, in which case <tt>null</tt> is returned.
1918      * @since 1.5
1919      * @return the uncaught exception handler for this thread
1920      */
1921     public UncaughtExceptionHandler getUncaughtExceptionHandler() {
1922         return uncaughtExceptionHandler != null ?
1923             uncaughtExceptionHandler : group;
1924     }
1925 
1926     /**
1927      * Set the handler invoked when this thread abruptly terminates
1928      * due to an uncaught exception.
1929      * <p>A thread can take full control of how it responds to uncaught
1930      * exceptions by having its uncaught exception handler explicitly set.
1931      * If no such handler is set then the thread's <tt>ThreadGroup</tt>
1932      * object acts as its handler.
1933      * @param eh the object to use as this thread's uncaught exception
1934      * handler. If <tt>null</tt> then this thread has no explicit handler.
1935      * @throws  SecurityException  if the current thread is not allowed to
1936      *          modify this thread.
1937      * @see #setDefaultUncaughtExceptionHandler
1938      * @see ThreadGroup#uncaughtException
1939      * @since 1.5
1940      */
1941     public void setUncaughtExceptionHandler(UncaughtExceptionHandler eh) {
1942         checkAccess();
1943         uncaughtExceptionHandler = eh;
1944     }
1945 
1946     /**
1947      * Dispatch an uncaught exception to the handler. This method is
1948      * intended to be called only by the JVM.
1949      */
1950     private void dispatchUncaughtException(Throwable e) {
1951         getUncaughtExceptionHandler().uncaughtException(this, e);
1952     }
1953 
1954     /**
1955      * Removes from the specified map any keys that have been enqueued
1956      * on the specified reference queue.
1957      */
1958     static void processQueue(ReferenceQueue<Class<?>> queue,
1959                              ConcurrentMap<? extends
1960                              WeakReference<Class<?>>, ?> map)
1961     {
1962         Reference<? extends Class<?>> ref;
1963         while((ref = queue.poll()) != null) {
1964             map.remove(ref);
1965         }
1966     }
1967 
1968     /**
1969      *  Weak key for Class objects.
1970      **/
1971     static class WeakClassKey extends WeakReference<Class<?>> {
1972         /**
1973          * saved value of the referent's identity hash code, to maintain
1974          * a consistent hash code after the referent has been cleared
1975          */
1976         private final int hash;
1977 
1978         /**
1979          * Create a new WeakClassKey to the given object, registered
1980          * with a queue.
1981          */
1982         WeakClassKey(Class<?> cl, ReferenceQueue<Class<?>> refQueue) {
1983             super(cl, refQueue);
1984             hash = System.identityHashCode(cl);
1985         }
1986 
1987         /**
1988          * Returns the identity hash code of the original referent.
1989          */
1990         @Override
1991         public int hashCode() {
1992             return hash;
1993         }
1994 
1995         /**
1996          * Returns true if the given object is this identical
1997          * WeakClassKey instance, or, if this object's referent has not
1998          * been cleared, if the given object is another WeakClassKey
1999          * instance with the identical non-null referent as this one.
2000          */
2001         @Override
2002         public boolean equals(Object obj) {
2003             if (obj == this)
2004                 return true;
2005 
2006             if (obj instanceof WeakClassKey) {
2007                 Object referent = get();
2008                 return (referent != null) &&
2009                        (referent == ((WeakClassKey) obj).get());
2010             } else {
2011                 return false;
2012             }
2013         }
2014     }
2015 
2016 
2017     // The following three initially uninitialized fields are exclusively
2018     // managed by class java.util.concurrent.ThreadLocalRandom. These
2019     // fields are used to build the high-performance PRNGs in the
2020     // concurrent code, and we can not risk accidental false sharing.
2021     // Hence, the fields are isolated with @Contended.
2022 
2023     /** The current seed for a ThreadLocalRandom */
2024     @sun.misc.Contended("tlr")
2025     long threadLocalRandomSeed;
2026 
2027     /** Probe hash value; nonzero if threadLocalRandomSeed initialized */
2028     @sun.misc.Contended("tlr")
2029     int threadLocalRandomProbe;
2030 
2031     /** Secondary seed isolated from public ThreadLocalRandom sequence */
2032     @sun.misc.Contended("tlr")
2033     int threadLocalRandomSecondarySeed;
2034 
2035     /* Some private helper methods */
2036     private native void setPriority0(int newPriority);
2037     private native void stop0(Object o);
2038     private native void suspend0();
2039     private native void resume0();
2040     private native void interrupt0();
2041     private native void setNativeName(String name);
2042 }