1 /*
2 * Copyright (c) 1994, 2018, 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
18 * 2 along with this work; if not, write to the Free Software Foundation,
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
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
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.TimeUnit;
39 import java.util.concurrent.locks.LockSupport;
40
41 import jdk.internal.misc.TerminatingThreadLocal;
42 import sun.nio.ch.Interruptible;
43 import jdk.internal.reflect.CallerSensitive;
44 import jdk.internal.reflect.Reflection;
45 import sun.security.util.SecurityConstants;
46 import jdk.internal.HotSpotIntrinsicCandidate;
47
48 /**
49 * A <i>thread</i> is a thread of execution in a program. The Java
50 * Virtual Machine allows an application to have multiple threads of
51 * execution running concurrently.
52 * <p>
53 * Every thread has a priority. Threads with higher priority are
54 * executed in preference to threads with lower priority. Each thread
55 * may or may not also be marked as a daemon. When code running in
56 * some thread creates a new {@code Thread} object, the new
57 * thread has its priority initially set equal to the priority of the
58 * creating thread, and is a daemon thread if and only if the
59 * creating thread is a daemon.
60 * <p>
61 * When a Java Virtual Machine starts up, there is usually a single
62 * non-daemon thread (which typically calls the method named
63 * {@code main} of some designated class). The Java Virtual
64 * Machine continues to execute threads until either of the following
65 * occurs:
66 * <ul>
67 * <li>The {@code exit} method of class {@code Runtime} has been
68 * called and the security manager has permitted the exit operation
69 * to take place.
70 * <li>All threads that are not daemon threads have died, either by
71 * returning from the call to the {@code run} method or by
72 * throwing an exception that propagates beyond the {@code run}
73 * method.
74 * </ul>
75 * <p>
76 * There are two ways to create a new thread of execution. One is to
77 * declare a class to be a subclass of {@code Thread}. This
78 * subclass should override the {@code run} method of class
79 * {@code Thread}. An instance of the subclass can then be
80 * allocated and started. For example, a thread that computes primes
81 * larger than a stated value could be written as follows:
82 * <hr><blockquote><pre>
83 * class PrimeThread extends Thread {
84 * long minPrime;
85 * PrimeThread(long minPrime) {
86 * this.minPrime = minPrime;
87 * }
88 *
89 * public void run() {
90 * // compute primes larger than minPrime
91 * . . .
92 * }
93 * }
94 * </pre></blockquote><hr>
95 * <p>
96 * The following code would then create a thread and start it running:
97 * <blockquote><pre>
98 * PrimeThread p = new PrimeThread(143);
99 * p.start();
100 * </pre></blockquote>
101 * <p>
102 * The other way to create a thread is to declare a class that
103 * implements the {@code Runnable} interface. That class then
104 * implements the {@code run} method. An instance of the class can
105 * then be allocated, passed as an argument when creating
106 * {@code Thread}, and started. The same example in this other
107 * style looks like the following:
108 * <hr><blockquote><pre>
109 * class PrimeRun implements Runnable {
110 * long minPrime;
111 * PrimeRun(long minPrime) {
112 * this.minPrime = minPrime;
113 * }
114 *
115 * public void run() {
116 * // compute primes larger than minPrime
117 * . . .
118 * }
119 * }
120 * </pre></blockquote><hr>
121 * <p>
122 * The following code would then create a thread and start it running:
123 * <blockquote><pre>
124 * PrimeRun p = new PrimeRun(143);
125 * new Thread(p).start();
126 * </pre></blockquote>
127 * <p>
128 * Every thread has a name for identification purposes. More than
129 * one thread may have the same name. If a name is not specified when
130 * a thread is created, a new name is generated for it.
131 * <p>
132 * Unless otherwise noted, passing a {@code null} argument to a constructor
133 * or method in this class will cause a {@link NullPointerException} to be
134 * thrown.
135 *
136 * @author unascribed
137 * @see Runnable
138 * @see Runtime#exit(int)
139 * @see #run()
140 * @see #stop()
141 * @since 1.0
142 */
143 public
144 class Thread implements Runnable {
145 /* Make sure registerNatives is the first thing <clinit> does. */
146 private static native void registerNatives();
147 static {
148 registerNatives();
149 }
150
151 private volatile String name;
152 private int priority;
153
154 /* Whether or not the thread is a daemon thread. */
155 private boolean daemon = false;
156
157 /* Fields reserved for exclusive use by the JVM */
158 private boolean stillborn = false;
159 private long eetop;
160
161 /* What will be run. */
162 private Runnable target;
163
164 /* The group of this thread */
165 private ThreadGroup group;
166
167 /* The context ClassLoader for this thread */
168 private ClassLoader contextClassLoader;
169
170 /* The inherited AccessControlContext of this thread */
171 private AccessControlContext inheritedAccessControlContext;
172
173 /* For autonumbering anonymous threads. */
174 private static int threadInitNumber;
175 private static synchronized int nextThreadNum() {
176 return threadInitNumber++;
177 }
178
179 /* ThreadLocal values pertaining to this thread. This map is maintained
180 * by the ThreadLocal class. */
181 ThreadLocal.ThreadLocalMap threadLocals = null;
182
183 /*
184 * InheritableThreadLocal values pertaining to this thread. This map is
185 * maintained by the InheritableThreadLocal class.
186 */
187 ThreadLocal.ThreadLocalMap inheritableThreadLocals = null;
188
189 /*
190 * The requested stack size for this thread, or 0 if the creator did
191 * not specify a stack size. It is up to the VM to do whatever it
192 * likes with this number; some VMs will ignore it.
193 */
194 private final long stackSize;
195
196 /*
197 * JVM-private state that persists after native thread termination.
198 */
199 private long nativeParkEventPointer;
200
201 /*
202 * Thread ID
203 */
204 private final long tid;
205
206 /* For generating thread ID */
207 private static long threadSeqNumber;
208
209 private static synchronized long nextThreadID() {
210 return ++threadSeqNumber;
211 }
212
213 /*
214 * Java thread status for tools, default indicates thread 'not yet started'
215 */
216 private volatile int threadStatus;
217
218 /**
219 * The argument supplied to the current call to
220 * java.util.concurrent.locks.LockSupport.park.
221 * Set by (private) java.util.concurrent.locks.LockSupport.setBlocker
222 * Accessed using java.util.concurrent.locks.LockSupport.getBlocker
223 */
224 volatile Object parkBlocker;
225
226 /* The object in which this thread is blocked in an interruptible I/O
227 * operation, if any. The blocker's interrupt method should be invoked
228 * after setting this thread's interrupt status.
229 */
230 private volatile Interruptible blocker;
231 private final Object blockerLock = new Object();
232
233 /* Set the blocker field; invoked via jdk.internal.access.SharedSecrets
234 * from java.nio code
235 */
236 static void blockedOn(Interruptible b) {
237 Thread me = Thread.currentThread();
238 synchronized (me.blockerLock) {
239 me.blocker = b;
240 }
241 }
242
243 /**
244 * The minimum priority that a thread can have.
245 */
246 public static final int MIN_PRIORITY = 1;
247
248 /**
249 * The default priority that is assigned to a thread.
250 */
251 public static final int NORM_PRIORITY = 5;
252
253 /**
254 * The maximum priority that a thread can have.
255 */
256 public static final int MAX_PRIORITY = 10;
257
258 /**
259 * Returns a reference to the currently executing thread object.
260 *
261 * @return the currently executing thread.
262 */
263 @HotSpotIntrinsicCandidate
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 > 0 && millis < Long.MAX_VALUE) {
337 millis++;
338 }
339
340 sleep(millis);
341 }
342
343 /**
344 * Indicates that the caller is momentarily unable to progress, until the
345 * occurrence of one or more actions on the part of other activities. By
346 * invoking this method within each iteration of a spin-wait loop construct,
347 * the calling thread indicates to the runtime that it is busy-waiting.
348 * The runtime may take action to improve the performance of invoking
349 * spin-wait loop constructions.
350 *
351 * @apiNote
352 * As an example consider a method in a class that spins in a loop until
353 * some flag is set outside of that method. A call to the {@code onSpinWait}
354 * method should be placed inside the spin loop.
355 * <pre>{@code
356 * class EventHandler {
357 * volatile boolean eventNotificationNotReceived;
358 * void waitForEventAndHandleIt() {
359 * while ( eventNotificationNotReceived ) {
360 * java.lang.Thread.onSpinWait();
361 * }
362 * readAndProcessEvent();
363 * }
364 *
365 * void readAndProcessEvent() {
366 * // Read event from some source and process it
367 * . . .
368 * }
369 * }
370 * }</pre>
371 * <p>
372 * The code above would remain correct even if the {@code onSpinWait}
373 * method was not called at all. However on some architectures the Java
374 * Virtual Machine may issue the processor instructions to address such
375 * code patterns in a more beneficial way.
376 *
377 * @since 9
378 */
379 @HotSpotIntrinsicCandidate
380 public static void onSpinWait() {}
381
382 /**
383 * Initializes a Thread.
384 *
385 * @param g the Thread group
386 * @param target the object whose run() method gets called
387 * @param name the name of the new Thread
388 * @param stackSize the desired stack size for the new thread, or
389 * zero to indicate that this parameter is to be ignored.
390 * @param acc the AccessControlContext to inherit, or
391 * AccessController.getContext() if null
392 * @param inheritThreadLocals if {@code true}, inherit initial values for
393 * inheritable thread-locals from the constructing thread
394 */
395 private Thread(ThreadGroup g, Runnable target, String name,
396 long stackSize, AccessControlContext acc,
397 boolean inheritThreadLocals) {
398 if (name == null) {
399 throw new NullPointerException("name cannot be null");
400 }
401
402 this.name = name;
403
404 Thread parent = currentThread();
405 SecurityManager security = System.getSecurityManager();
406 if (g == null) {
407 /* Determine if it's an applet or not */
408
409 /* If there is a security manager, ask the security manager
410 what to do. */
411 if (security != null) {
412 g = security.getThreadGroup();
413 }
414
415 /* If the security manager doesn't have a strong opinion
416 on the matter, use the parent thread group. */
417 if (g == null) {
418 g = parent.getThreadGroup();
419 }
420 }
421
422 /* checkAccess regardless of whether or not threadgroup is
423 explicitly passed in. */
424 g.checkAccess();
425
426 /*
427 * Do we have the required permissions?
428 */
429 if (security != null) {
430 if (isCCLOverridden(getClass())) {
431 security.checkPermission(
432 SecurityConstants.SUBCLASS_IMPLEMENTATION_PERMISSION);
433 }
434 }
435
436 g.addUnstarted();
437
438 this.group = g;
439 this.daemon = parent.isDaemon();
440 this.priority = parent.getPriority();
441 if (security == null || isCCLOverridden(parent.getClass()))
442 this.contextClassLoader = parent.getContextClassLoader();
443 else
444 this.contextClassLoader = parent.contextClassLoader;
445 this.inheritedAccessControlContext =
446 acc != null ? acc : AccessController.getContext();
447 this.target = target;
448 setPriority(priority);
449 if (inheritThreadLocals && parent.inheritableThreadLocals != null)
450 this.inheritableThreadLocals =
451 ThreadLocal.createInheritedMap(parent.inheritableThreadLocals);
452 /* Stash the specified stack size in case the VM cares */
453 this.stackSize = stackSize;
454
455 /* Set thread ID */
456 this.tid = nextThreadID();
457 }
458
459 /**
460 * Throws CloneNotSupportedException as a Thread can not be meaningfully
461 * cloned. Construct a new Thread instead.
462 *
463 * @throws CloneNotSupportedException
464 * always
465 */
466 @Override
467 protected Object clone() throws CloneNotSupportedException {
468 throw new CloneNotSupportedException();
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 (null, null, 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 public Thread() {
479 this(null, null, "Thread-" + nextThreadNum(), 0);
480 }
481
482 /**
483 * Allocates a new {@code Thread} object. This constructor has the same
484 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
485 * {@code (null, target, gname)}, where {@code gname} is a newly generated
486 * name. Automatically generated names are of the form
487 * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
488 *
489 * @param target
490 * the object whose {@code run} method is invoked when this thread
491 * is started. If {@code null}, this classes {@code run} method does
492 * nothing.
493 */
494 public Thread(Runnable target) {
495 this(null, target, "Thread-" + nextThreadNum(), 0);
496 }
497
498 /**
499 * Creates a new Thread that inherits the given AccessControlContext
500 * but thread-local variables are not inherited.
501 * This is not a public constructor.
502 */
503 Thread(Runnable target, AccessControlContext acc) {
504 this(null, target, "Thread-" + nextThreadNum(), 0, acc, false);
505 }
506
507 /**
508 * Allocates a new {@code Thread} object. This constructor has the same
509 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
510 * {@code (group, target, gname)} ,where {@code gname} is a newly generated
511 * name. Automatically generated names are of the form
512 * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
513 *
514 * @param group
515 * the thread group. If {@code null} and there is a security
516 * manager, the group is determined by {@linkplain
517 * SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
518 * If there is not a security manager or {@code
519 * SecurityManager.getThreadGroup()} returns {@code null}, the group
520 * is set to the current thread's thread group.
521 *
522 * @param target
523 * the object whose {@code run} method is invoked when this thread
524 * is started. If {@code null}, this thread's run method is invoked.
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, Runnable target) {
531 this(group, target, "Thread-" + nextThreadNum(), 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, null, name)}.
538 *
539 * @param name
540 * the name of the new thread
541 */
542 public Thread(String name) {
543 this(null, null, name, 0);
544 }
545
546 /**
547 * Allocates a new {@code Thread} object. This constructor has the same
548 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
549 * {@code (group, null, name)}.
550 *
551 * @param group
552 * the thread group. If {@code null} and there is a security
553 * manager, the group is determined by {@linkplain
554 * SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
555 * If there is not a security manager or {@code
556 * SecurityManager.getThreadGroup()} returns {@code null}, the group
557 * is set to the current thread's thread group.
558 *
559 * @param name
560 * the name of the new thread
561 *
562 * @throws SecurityException
563 * if the current thread cannot create a thread in the specified
564 * thread group
565 */
566 public Thread(ThreadGroup group, String name) {
567 this(group, null, name, 0);
568 }
569
570 /**
571 * Allocates a new {@code Thread} object. This constructor has the same
572 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
573 * {@code (null, target, name)}.
574 *
575 * @param target
576 * the object whose {@code run} method is invoked when this thread
577 * is started. If {@code null}, this thread's run method is invoked.
578 *
579 * @param name
580 * the name of the new thread
581 */
582 public Thread(Runnable target, String name) {
583 this(null, target, name, 0);
584 }
585
586 /**
587 * Allocates a new {@code Thread} object so that it has {@code target}
588 * as its run object, has the specified {@code name} as its name,
589 * and belongs to the thread group referred to by {@code group}.
590 *
591 * <p>If there is a security manager, its
592 * {@link SecurityManager#checkAccess(ThreadGroup) checkAccess}
593 * method is invoked with the ThreadGroup as its argument.
594 *
595 * <p>In addition, its {@code checkPermission} method is invoked with
596 * the {@code RuntimePermission("enableContextClassLoaderOverride")}
597 * permission when invoked directly or indirectly by the constructor
598 * of a subclass which overrides the {@code getContextClassLoader}
599 * or {@code setContextClassLoader} methods.
600 *
601 * <p>The priority of the newly created thread is set equal to the
602 * priority of the thread creating it, that is, the currently running
603 * thread. The method {@linkplain #setPriority setPriority} may be
604 * used to change the priority to a new value.
605 *
606 * <p>The newly created thread is initially marked as being a daemon
607 * thread if and only if the thread creating it is currently marked
608 * as a daemon thread. The method {@linkplain #setDaemon setDaemon}
609 * may be used to change whether or not a thread is a daemon.
610 *
611 * @param group
612 * the thread group. If {@code null} and there is a security
613 * manager, the group is determined by {@linkplain
614 * SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
615 * If there is not a security manager or {@code
616 * SecurityManager.getThreadGroup()} returns {@code null}, the group
617 * is set to the current thread's thread group.
618 *
619 * @param target
620 * the object whose {@code run} method is invoked when this thread
621 * is started. If {@code null}, this thread's run method is invoked.
622 *
623 * @param name
624 * the name of the new thread
625 *
626 * @throws SecurityException
627 * if the current thread cannot create a thread in the specified
628 * thread group or cannot override the context class loader methods.
629 */
630 public Thread(ThreadGroup group, Runnable target, String name) {
631 this(group, target, name, 0);
632 }
633
634 /**
635 * Allocates a new {@code Thread} object so that it has {@code target}
636 * as its run object, has the specified {@code name} as its name,
637 * and belongs to the thread group referred to by {@code group}, and has
638 * the specified <i>stack size</i>.
639 *
640 * <p>This constructor is identical to {@link
641 * #Thread(ThreadGroup,Runnable,String)} with the exception of the fact
642 * that it allows the thread stack size to be specified. The stack size
643 * is the approximate number of bytes of address space that the virtual
644 * machine is to allocate for this thread's stack. <b>The effect of the
645 * {@code stackSize} parameter, if any, is highly platform dependent.</b>
646 *
647 * <p>On some platforms, specifying a higher value for the
648 * {@code stackSize} parameter may allow a thread to achieve greater
649 * recursion depth before throwing a {@link StackOverflowError}.
650 * Similarly, specifying a lower value may allow a greater number of
651 * threads to exist concurrently without throwing an {@link
652 * OutOfMemoryError} (or other internal error). The details of
653 * the relationship between the value of the {@code stackSize} parameter
654 * and the maximum recursion depth and concurrency level are
655 * platform-dependent. <b>On some platforms, the value of the
656 * {@code stackSize} parameter may have no effect whatsoever.</b>
657 *
658 * <p>The virtual machine is free to treat the {@code stackSize}
659 * parameter as a suggestion. If the specified value is unreasonably low
660 * for the platform, the virtual machine may instead use some
661 * platform-specific minimum value; if the specified value is unreasonably
662 * high, the virtual machine may instead use some platform-specific
663 * maximum. Likewise, the virtual machine is free to round the specified
664 * value up or down as it sees fit (or to ignore it completely).
665 *
666 * <p>Specifying a value of zero for the {@code stackSize} parameter will
667 * cause this constructor to behave exactly like the
668 * {@code Thread(ThreadGroup, Runnable, String)} constructor.
669 *
670 * <p><i>Due to the platform-dependent nature of the behavior of this
671 * constructor, extreme care should be exercised in its use.
672 * The thread stack size necessary to perform a given computation will
673 * likely vary from one JRE implementation to another. In light of this
674 * variation, careful tuning of the stack size parameter may be required,
675 * and the tuning may need to be repeated for each JRE implementation on
676 * which an application is to run.</i>
677 *
678 * <p>Implementation note: Java platform implementers are encouraged to
679 * document their implementation's behavior with respect to the
680 * {@code stackSize} parameter.
681 *
682 *
683 * @param group
684 * the thread group. If {@code null} and there is a security
685 * manager, the group is determined by {@linkplain
686 * SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
687 * If there is not a security manager or {@code
688 * SecurityManager.getThreadGroup()} returns {@code null}, the group
689 * is set to the current thread's thread group.
690 *
691 * @param target
692 * the object whose {@code run} method is invoked when this thread
693 * is started. If {@code null}, this thread's run method is invoked.
694 *
695 * @param name
696 * the name of the new thread
697 *
698 * @param stackSize
699 * the desired stack size for the new thread, or zero to indicate
700 * that this parameter is to be ignored.
701 *
702 * @throws SecurityException
703 * if the current thread cannot create a thread in the specified
704 * thread group
705 *
706 * @since 1.4
707 */
708 public Thread(ThreadGroup group, Runnable target, String name,
709 long stackSize) {
710 this(group, target, name, stackSize, null, true);
711 }
712
713 /**
714 * Allocates a new {@code Thread} object so that it has {@code target}
715 * as its run object, has the specified {@code name} as its name,
716 * belongs to the thread group referred to by {@code group}, has
717 * the specified {@code stackSize}, and inherits initial values for
718 * {@linkplain InheritableThreadLocal inheritable thread-local} variables
719 * if {@code inheritThreadLocals} is {@code true}.
720 *
721 * <p> This constructor is identical to {@link
722 * #Thread(ThreadGroup,Runnable,String,long)} with the added ability to
723 * suppress, or not, the inheriting of initial values for inheritable
724 * thread-local variables from the constructing thread. This allows for
725 * finer grain control over inheritable thread-locals. Care must be taken
726 * when passing a value of {@code false} for {@code inheritThreadLocals},
727 * as it may lead to unexpected behavior if the new thread executes code
728 * that expects a specific thread-local value to be inherited.
729 *
730 * <p> Specifying a value of {@code true} for the {@code inheritThreadLocals}
731 * parameter will cause this constructor to behave exactly like the
732 * {@code Thread(ThreadGroup, Runnable, String, long)} constructor.
733 *
734 * @param group
735 * the thread group. If {@code null} and there is a security
736 * manager, the group is determined by {@linkplain
737 * SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
738 * If there is not a security manager or {@code
739 * SecurityManager.getThreadGroup()} returns {@code null}, the group
740 * is set to the current thread's thread group.
741 *
742 * @param target
743 * the object whose {@code run} method is invoked when this thread
744 * is started. If {@code null}, this thread's run method is invoked.
745 *
746 * @param name
747 * the name of the new thread
748 *
749 * @param stackSize
750 * the desired stack size for the new thread, or zero to indicate
751 * that this parameter is to be ignored
752 *
753 * @param inheritThreadLocals
754 * if {@code true}, inherit initial values for inheritable
755 * thread-locals from the constructing thread, otherwise no initial
756 * values are inherited
757 *
758 * @throws SecurityException
759 * if the current thread cannot create a thread in the specified
760 * thread group
761 *
762 * @since 9
763 */
764 public Thread(ThreadGroup group, Runnable target, String name,
765 long stackSize, boolean inheritThreadLocals) {
766 this(group, target, name, stackSize, null, inheritThreadLocals);
767 }
768
769 /**
770 * Causes this thread to begin execution; the Java Virtual Machine
771 * calls the {@code run} method of this thread.
772 * <p>
773 * The result is that two threads are running concurrently: the
774 * current thread (which returns from the call to the
775 * {@code start} method) and the other thread (which executes its
776 * {@code run} method).
777 * <p>
778 * It is never legal to start a thread more than once.
779 * In particular, a thread may not be restarted once it has completed
780 * execution.
781 *
782 * @throws IllegalThreadStateException if the thread was already started.
783 * @see #run()
784 * @see #stop()
785 */
786 public synchronized void start() {
787 /**
788 * This method is not invoked for the main method thread or "system"
789 * group threads created/set up by the VM. Any new functionality added
790 * to this method in the future may have to also be added to the VM.
791 *
792 * A zero status value corresponds to state "NEW".
793 */
794 if (threadStatus != 0)
795 throw new IllegalThreadStateException();
796
797 /* Notify the group that this thread is about to be started
798 * so that it can be added to the group's list of threads
799 * and the group's unstarted count can be decremented. */
800 group.add(this);
801
802 boolean started = false;
803 try {
804 start0();
805 started = true;
806 } finally {
807 try {
808 if (!started) {
809 group.threadStartFailed(this);
810 }
811 } catch (Throwable ignore) {
812 /* do nothing. If start0 threw a Throwable then
813 it will be passed up the call stack */
814 }
815 }
816 }
817
818 private native void start0();
819
820 /**
821 * If this thread was constructed using a separate
822 * {@code Runnable} run object, then that
823 * {@code Runnable} object's {@code run} method is called;
824 * otherwise, this method does nothing and returns.
825 * <p>
826 * Subclasses of {@code Thread} should override this method.
827 *
828 * @see #start()
829 * @see #stop()
830 * @see #Thread(ThreadGroup, Runnable, String)
831 */
832 @Override
833 public void run() {
834 if (target != null) {
835 target.run();
836 }
837 }
838
839 /**
840 * This method is called by the system to give a Thread
841 * a chance to clean up before it actually exits.
842 */
843 private void exit() {
844 if (threadLocals != null && TerminatingThreadLocal.REGISTRY.isPresent()) {
845 TerminatingThreadLocal.threadTerminated();
846 }
847 if (group != null) {
848 group.threadTerminated(this);
849 group = null;
850 }
851 /* Aggressively null out all reference fields: see bug 4006245 */
852 target = null;
853 /* Speed the release of some of these resources */
854 threadLocals = null;
855 inheritableThreadLocals = null;
856 inheritedAccessControlContext = null;
857 blocker = null;
858 uncaughtExceptionHandler = null;
859 }
860
861 /**
862 * Forces the thread to stop executing.
863 * <p>
864 * If there is a security manager installed, its {@code checkAccess}
865 * method is called with {@code this}
866 * as its argument. This may result in a
867 * {@code SecurityException} being raised (in the current thread).
868 * <p>
869 * If this thread is different from the current thread (that is, the current
870 * thread is trying to stop a thread other than itself), the
871 * security manager's {@code checkPermission} method (with a
872 * {@code RuntimePermission("stopThread")} argument) is called in
873 * addition.
874 * Again, this may result in throwing a
875 * {@code SecurityException} (in the current thread).
876 * <p>
877 * The thread represented by this thread is forced to stop whatever
878 * it is doing abnormally and to throw a newly created
879 * {@code ThreadDeath} object as an exception.
880 * <p>
881 * It is permitted to stop a thread that has not yet been started.
882 * If the thread is eventually started, it immediately terminates.
883 * <p>
884 * An application should not normally try to catch
885 * {@code ThreadDeath} unless it must do some extraordinary
886 * cleanup operation (note that the throwing of
887 * {@code ThreadDeath} causes {@code finally} clauses of
888 * {@code try} statements to be executed before the thread
889 * officially dies). If a {@code catch} clause catches a
890 * {@code ThreadDeath} object, it is important to rethrow the
891 * object so that the thread actually dies.
892 * <p>
893 * The top-level error handler that reacts to otherwise uncaught
894 * exceptions does not print out a message or otherwise notify the
895 * application if the uncaught exception is an instance of
896 * {@code ThreadDeath}.
897 *
898 * @throws SecurityException if the current thread cannot
899 * modify this thread.
900 * @see #interrupt()
901 * @see #checkAccess()
902 * @see #run()
903 * @see #start()
904 * @see ThreadDeath
905 * @see ThreadGroup#uncaughtException(Thread,Throwable)
906 * @see SecurityManager#checkAccess(Thread)
907 * @see SecurityManager#checkPermission
908 * @deprecated This method is inherently unsafe. Stopping a thread with
909 * Thread.stop causes it to unlock all of the monitors that it
910 * has locked (as a natural consequence of the unchecked
911 * {@code ThreadDeath} exception propagating up the stack). If
912 * any of the objects previously protected by these monitors were in
913 * an inconsistent state, the damaged objects become visible to
914 * other threads, potentially resulting in arbitrary behavior. Many
915 * uses of {@code stop} should be replaced by code that simply
916 * modifies some variable to indicate that the target thread should
917 * stop running. The target thread should check this variable
918 * regularly, and return from its run method in an orderly fashion
919 * if the variable indicates that it is to stop running. If the
920 * target thread waits for long periods (on a condition variable,
921 * for example), the {@code interrupt} method should be used to
922 * interrupt the wait.
923 * For more information, see
924 * <a href="{@docRoot}/java.base/java/lang/doc-files/threadPrimitiveDeprecation.html">Why
925 * are Thread.stop, Thread.suspend and Thread.resume Deprecated?</a>.
926 */
927 @Deprecated(since="1.2")
928 public final void stop() {
929 SecurityManager security = System.getSecurityManager();
930 if (security != null) {
931 checkAccess();
932 if (this != Thread.currentThread()) {
933 security.checkPermission(SecurityConstants.STOP_THREAD_PERMISSION);
934 }
935 }
936 // A zero status value corresponds to "NEW", it can't change to
937 // not-NEW because we hold the lock.
938 if (threadStatus != 0) {
939 resume(); // Wake up thread if it was suspended; no-op otherwise
940 }
941
942 // The VM can handle all thread states
943 stop0(new ThreadDeath());
944 }
945
946 /**
947 * Interrupts this thread.
948 *
949 * <p> Unless the current thread is interrupting itself, which is
950 * always permitted, the {@link #checkAccess() checkAccess} method
951 * of this thread is invoked, which may cause a {@link
952 * SecurityException} to be thrown.
953 *
954 * <p> If this thread is blocked in an invocation of the {@link
955 * Object#wait() wait()}, {@link Object#wait(long) wait(long)}, or {@link
956 * Object#wait(long, int) wait(long, int)} methods of the {@link Object}
957 * class, or of the {@link #join()}, {@link #join(long)}, {@link
958 * #join(long, int)}, {@link #sleep(long)}, or {@link #sleep(long, int)},
959 * methods of this class, then its interrupt status will be cleared and it
960 * will receive an {@link InterruptedException}.
961 *
962 * <p> If this thread is blocked in an I/O operation upon an {@link
963 * java.nio.channels.InterruptibleChannel InterruptibleChannel}
964 * then the channel will be closed, the thread's interrupt
965 * status will be set, and the thread will receive a {@link
966 * java.nio.channels.ClosedByInterruptException}.
967 *
968 * <p> If this thread is blocked in a {@link java.nio.channels.Selector}
969 * then the thread's interrupt status will be set and it will return
970 * immediately from the selection operation, possibly with a non-zero
971 * value, just as if the selector's {@link
972 * java.nio.channels.Selector#wakeup wakeup} method were invoked.
973 *
974 * <p> If none of the previous conditions hold then this thread's interrupt
975 * status will be set. </p>
976 *
977 * <p> Interrupting a thread that is not alive need not have any effect.
978 *
979 * @throws SecurityException
980 * if the current thread cannot modify this thread
981 *
982 * @revised 6.0
983 * @spec JSR-51
984 */
985 public void interrupt() {
986 if (this != Thread.currentThread()) {
987 checkAccess();
988
989 // thread may be blocked in an I/O operation
990 synchronized (blockerLock) {
991 Interruptible b = blocker;
992 if (b != null) {
993 interrupt0(); // set interrupt status
994 b.interrupt(this);
995 return;
996 }
997 }
998 }
999
1000 // set interrupt status
1001 interrupt0();
1002 }
1003
1004 /**
1005 * Tests whether the current thread has been interrupted. The
1006 * <i>interrupted status</i> of the thread is cleared by this method. In
1007 * other words, if this method were to be called twice in succession, the
1008 * second call would return false (unless the current thread were
1009 * interrupted again, after the first call had cleared its interrupted
1010 * status and before the second call had examined it).
1011 *
1012 * <p>A thread interruption ignored because a thread was not alive
1013 * at the time of the interrupt will be reflected by this method
1014 * returning false.
1015 *
1016 * @return {@code true} if the current thread has been interrupted;
1017 * {@code false} otherwise.
1018 * @see #isInterrupted()
1019 * @revised 6.0
1020 */
1021 public static boolean interrupted() {
1022 return currentThread().isInterrupted(true);
1023 }
1024
1025 /**
1026 * Tests whether this thread has been interrupted. The <i>interrupted
1027 * status</i> of the thread is unaffected by this method.
1028 *
1029 * <p>A thread interruption ignored because a thread was not alive
1030 * at the time of the interrupt will be reflected by this method
1031 * returning false.
1032 *
1033 * @return {@code true} if this thread has been interrupted;
1034 * {@code false} otherwise.
1035 * @see #interrupted()
1036 * @revised 6.0
1037 */
1038 public boolean isInterrupted() {
1039 return isInterrupted(false);
1040 }
1041
1042 /**
1043 * Tests if some Thread has been interrupted. The interrupted state
1044 * is reset or not based on the value of ClearInterrupted that is
1045 * passed.
1046 */
1047 @HotSpotIntrinsicCandidate
1048 private native boolean isInterrupted(boolean ClearInterrupted);
1049
1050 /**
1051 * Tests if this thread is alive. A thread is alive if it has
1052 * been started and has not yet died.
1053 *
1054 * @return {@code true} if this thread is alive;
1055 * {@code false} otherwise.
1056 */
1057 public final native boolean isAlive();
1058
1059 /**
1060 * Suspends this thread.
1061 * <p>
1062 * First, the {@code checkAccess} method of this thread is called
1063 * with no arguments. This may result in throwing a
1064 * {@code SecurityException }(in the current thread).
1065 * <p>
1066 * If the thread is alive, it is suspended and makes no further
1067 * progress unless and until it is resumed.
1068 *
1069 * @throws SecurityException if the current thread cannot modify
1070 * this thread.
1071 * @see #checkAccess
1072 * @deprecated This method has been deprecated, as it is
1073 * inherently deadlock-prone. If the target thread holds a lock on the
1074 * monitor protecting a critical system resource when it is suspended, no
1075 * thread can access this resource until the target thread is resumed. If
1076 * the thread that would resume the target thread attempts to lock this
1077 * monitor prior to calling {@code resume}, deadlock results. Such
1078 * deadlocks typically manifest themselves as "frozen" processes.
1079 * For more information, see
1080 * <a href="{@docRoot}/java.base/java/lang/doc-files/threadPrimitiveDeprecation.html">Why
1081 * are Thread.stop, Thread.suspend and Thread.resume Deprecated?</a>.
1082 */
1083 @Deprecated(since="1.2")
1084 public final void suspend() {
1085 checkAccess();
1086 suspend0();
1087 }
1088
1089 /**
1090 * Resumes a suspended thread.
1091 * <p>
1092 * First, the {@code checkAccess} method of this thread is called
1093 * with no arguments. This may result in throwing a
1094 * {@code SecurityException} (in the current thread).
1095 * <p>
1096 * If the thread is alive but suspended, it is resumed and is
1097 * permitted to make progress in its execution.
1098 *
1099 * @throws SecurityException if the current thread cannot modify this
1100 * thread.
1101 * @see #checkAccess
1102 * @see #suspend()
1103 * @deprecated This method exists solely for use with {@link #suspend},
1104 * which has been deprecated because it is deadlock-prone.
1105 * For more information, see
1106 * <a href="{@docRoot}/java.base/java/lang/doc-files/threadPrimitiveDeprecation.html">Why
1107 * are Thread.stop, Thread.suspend and Thread.resume Deprecated?</a>.
1108 */
1109 @Deprecated(since="1.2")
1110 public final void resume() {
1111 checkAccess();
1112 resume0();
1113 }
1114
1115 /**
1116 * Changes the priority of this thread.
1117 * <p>
1118 * First the {@code checkAccess} method of this thread is called
1119 * with no arguments. This may result in throwing a {@code SecurityException}.
1120 * <p>
1121 * Otherwise, the priority of this thread is set to the smaller of
1122 * the specified {@code newPriority} and the maximum permitted
1123 * priority of the thread's thread group.
1124 *
1125 * @param newPriority priority to set this thread to
1126 * @throws IllegalArgumentException If the priority is not in the
1127 * range {@code MIN_PRIORITY} to
1128 * {@code MAX_PRIORITY}.
1129 * @throws SecurityException if the current thread cannot modify
1130 * this thread.
1131 * @see #getPriority
1132 * @see #checkAccess()
1133 * @see #getThreadGroup()
1134 * @see #MAX_PRIORITY
1135 * @see #MIN_PRIORITY
1136 * @see ThreadGroup#getMaxPriority()
1137 */
1138 public final void setPriority(int newPriority) {
1139 ThreadGroup g;
1140 checkAccess();
1141 if (newPriority > MAX_PRIORITY || newPriority < MIN_PRIORITY) {
1142 throw new IllegalArgumentException();
1143 }
1144 if((g = getThreadGroup()) != null) {
1145 if (newPriority > g.getMaxPriority()) {
1146 newPriority = g.getMaxPriority();
1147 }
1148 setPriority0(priority = newPriority);
1149 }
1150 }
1151
1152 /**
1153 * Returns this thread's priority.
1154 *
1155 * @return this thread's priority.
1156 * @see #setPriority
1157 */
1158 public final int getPriority() {
1159 return priority;
1160 }
1161
1162 /**
1163 * Changes the name of this thread to be equal to the argument {@code name}.
1164 * <p>
1165 * First the {@code checkAccess} method of this thread is called
1166 * with no arguments. This may result in throwing a
1167 * {@code SecurityException}.
1168 *
1169 * @param name the new name for this thread.
1170 * @throws SecurityException if the current thread cannot modify this
1171 * thread.
1172 * @see #getName
1173 * @see #checkAccess()
1174 */
1175 public final synchronized void setName(String name) {
1176 checkAccess();
1177 if (name == null) {
1178 throw new NullPointerException("name cannot be null");
1179 }
1180
1181 this.name = name;
1182 if (threadStatus != 0) {
1183 setNativeName(name);
1184 }
1185 }
1186
1187 /**
1188 * Returns this thread's name.
1189 *
1190 * @return this thread's name.
1191 * @see #setName(String)
1192 */
1193 public final String getName() {
1194 return name;
1195 }
1196
1197 /**
1198 * Returns the thread group to which this thread belongs.
1199 * This method returns null if this thread has died
1200 * (been stopped).
1201 *
1202 * @return this thread's thread group.
1203 */
1204 public final ThreadGroup getThreadGroup() {
1205 return group;
1206 }
1207
1208 /**
1209 * Returns an estimate of the number of active threads in the current
1210 * thread's {@linkplain java.lang.ThreadGroup thread group} and its
1211 * subgroups. Recursively iterates over all subgroups in the current
1212 * thread's thread group.
1213 *
1214 * <p> The value returned is only an estimate because the number of
1215 * threads may change dynamically while this method traverses internal
1216 * data structures, and might be affected by the presence of certain
1217 * system threads. This method is intended primarily for debugging
1218 * and monitoring purposes.
1219 *
1220 * @return an estimate of the number of active threads in the current
1221 * thread's thread group and in any other thread group that
1222 * has the current thread's thread group as an ancestor
1223 */
1224 public static int activeCount() {
1225 return currentThread().getThreadGroup().activeCount();
1226 }
1227
1228 /**
1229 * Copies into the specified array every active thread in the current
1230 * thread's thread group and its subgroups. This method simply
1231 * invokes the {@link java.lang.ThreadGroup#enumerate(Thread[])}
1232 * method of the current thread's thread group.
1233 *
1234 * <p> An application might use the {@linkplain #activeCount activeCount}
1235 * method to get an estimate of how big the array should be, however
1236 * <i>if the array is too short to hold all the threads, the extra threads
1237 * are silently ignored.</i> If it is critical to obtain every active
1238 * thread in the current thread's thread group and its subgroups, the
1239 * invoker should verify that the returned int value is strictly less
1240 * than the length of {@code tarray}.
1241 *
1242 * <p> Due to the inherent race condition in this method, it is recommended
1243 * that the method only be used for debugging and monitoring purposes.
1244 *
1245 * @param tarray
1246 * an array into which to put the list of threads
1247 *
1248 * @return the number of threads put into the array
1249 *
1250 * @throws SecurityException
1251 * if {@link java.lang.ThreadGroup#checkAccess} determines that
1252 * the current thread cannot access its thread group
1253 */
1254 public static int enumerate(Thread tarray[]) {
1255 return currentThread().getThreadGroup().enumerate(tarray);
1256 }
1257
1258 /**
1259 * Counts the number of stack frames in this thread. The thread must
1260 * be suspended.
1261 *
1262 * @return the number of stack frames in this thread.
1263 * @throws IllegalThreadStateException if this thread is not
1264 * suspended.
1265 * @deprecated The definition of this call depends on {@link #suspend},
1266 * which is deprecated. Further, the results of this call
1267 * were never well-defined.
1268 * This method is subject to removal in a future version of Java SE.
1269 * @see StackWalker
1270 */
1271 @Deprecated(since="1.2", forRemoval=true)
1272 public native int countStackFrames();
1273
1274 /**
1275 * Waits at most {@code millis} milliseconds for this thread to
1276 * die. A timeout of {@code 0} means to wait forever.
1277 *
1278 * <p> This implementation uses a loop of {@code this.wait} calls
1279 * conditioned on {@code this.isAlive}. As a thread terminates the
1280 * {@code this.notifyAll} method is invoked. It is recommended that
1281 * applications not use {@code wait}, {@code notify}, or
1282 * {@code notifyAll} on {@code Thread} instances.
1283 *
1284 * @param millis
1285 * the time to wait in milliseconds
1286 *
1287 * @throws IllegalArgumentException
1288 * if the value of {@code millis} is negative
1289 *
1290 * @throws InterruptedException
1291 * if any thread has interrupted the current thread. The
1292 * <i>interrupted status</i> of the current thread is
1293 * cleared when this exception is thrown.
1294 */
1295 public final synchronized void join(final long millis)
1296 throws InterruptedException {
1297 if (millis > 0) {
1298 if (isAlive()) {
1299 final long startTime = System.nanoTime();
1300 long delay = millis;
1301 do {
1302 wait(delay);
1303 } while (isAlive() && (delay = millis -
1304 TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startTime)) > 0);
1305 }
1306 } else if (millis == 0) {
1307 while (isAlive()) {
1308 wait(0);
1309 }
1310 } else {
1311 throw new IllegalArgumentException("timeout value is negative");
1312 }
1313 }
1314
1315 /**
1316 * Waits at most {@code millis} milliseconds plus
1317 * {@code nanos} nanoseconds for this thread to die.
1318 *
1319 * <p> This implementation uses a loop of {@code this.wait} calls
1320 * conditioned on {@code this.isAlive}. As a thread terminates the
1321 * {@code this.notifyAll} method is invoked. It is recommended that
1322 * applications not use {@code wait}, {@code notify}, or
1323 * {@code notifyAll} on {@code Thread} instances.
1324 *
1325 * @param millis
1326 * the time to wait in milliseconds
1327 *
1328 * @param nanos
1329 * {@code 0-999999} additional nanoseconds to wait
1330 *
1331 * @throws IllegalArgumentException
1332 * if the value of {@code millis} is negative, or the value
1333 * of {@code nanos} is not in the range {@code 0-999999}
1334 *
1335 * @throws InterruptedException
1336 * if any thread has interrupted the current thread. The
1337 * <i>interrupted status</i> of the current thread is
1338 * cleared when this exception is thrown.
1339 */
1340 public final synchronized void join(long millis, int nanos)
1341 throws InterruptedException {
1342
1343 if (millis < 0) {
1344 throw new IllegalArgumentException("timeout value is negative");
1345 }
1346
1347 if (nanos < 0 || nanos > 999999) {
1348 throw new IllegalArgumentException(
1349 "nanosecond timeout value out of range");
1350 }
1351
1352 if (nanos > 0 && millis < Long.MAX_VALUE) {
1353 millis++;
1354 }
1355
1356 join(millis);
1357 }
1358
1359 /**
1360 * Waits for this thread to die.
1361 *
1362 * <p> An invocation of this method behaves in exactly the same
1363 * way as the invocation
1364 *
1365 * <blockquote>
1366 * {@linkplain #join(long) join}{@code (0)}
1367 * </blockquote>
1368 *
1369 * @throws InterruptedException
1370 * if any thread has interrupted the current thread. The
1371 * <i>interrupted status</i> of the current thread is
1372 * cleared when this exception is thrown.
1373 */
1374 public final void join() throws InterruptedException {
1375 join(0);
1376 }
1377
1378 /**
1379 * Prints a stack trace of the current thread to the standard error stream.
1380 * This method is used only for debugging.
1381 */
1382 public static void dumpStack() {
1383 new Exception("Stack trace").printStackTrace();
1384 }
1385
1386 /**
1387 * Marks this thread as either a {@linkplain #isDaemon daemon} thread
1388 * or a user thread. The Java Virtual Machine exits when the only
1389 * threads running are all daemon threads.
1390 *
1391 * <p> This method must be invoked before the thread is started.
1392 *
1393 * @param on
1394 * if {@code true}, marks this thread as a daemon thread
1395 *
1396 * @throws IllegalThreadStateException
1397 * if this thread is {@linkplain #isAlive alive}
1398 *
1399 * @throws SecurityException
1400 * if {@link #checkAccess} determines that the current
1401 * thread cannot modify this thread
1402 */
1403 public final void setDaemon(boolean on) {
1404 checkAccess();
1405 if (isAlive()) {
1406 throw new IllegalThreadStateException();
1407 }
1408 daemon = on;
1409 }
1410
1411 /**
1412 * Tests if this thread is a daemon thread.
1413 *
1414 * @return {@code true} if this thread is a daemon thread;
1415 * {@code false} otherwise.
1416 * @see #setDaemon(boolean)
1417 */
1418 public final boolean isDaemon() {
1419 return daemon;
1420 }
1421
1422 /**
1423 * Determines if the currently running thread has permission to
1424 * modify this thread.
1425 * <p>
1426 * If there is a security manager, its {@code checkAccess} method
1427 * is called with this thread as its argument. This may result in
1428 * throwing a {@code SecurityException}.
1429 *
1430 * @throws SecurityException if the current thread is not allowed to
1431 * access this thread.
1432 * @see SecurityManager#checkAccess(Thread)
1433 */
1434 public final void checkAccess() {
1435 SecurityManager security = System.getSecurityManager();
1436 if (security != null) {
1437 security.checkAccess(this);
1438 }
1439 }
1440
1441 /**
1442 * Returns a string representation of this thread, including the
1443 * thread's name, priority, and thread group.
1444 *
1445 * @return a string representation of this thread.
1446 */
1447 public String toString() {
1448 ThreadGroup group = getThreadGroup();
1449 if (group != null) {
1450 return "Thread[" + getName() + "," + getPriority() + "," +
1451 group.getName() + "]";
1452 } else {
1453 return "Thread[" + getName() + "," + getPriority() + "," +
1454 "" + "]";
1455 }
1456 }
1457
1458 /**
1459 * Returns the context {@code ClassLoader} for this thread. The context
1460 * {@code ClassLoader} is provided by the creator of the thread for use
1461 * by code running in this thread when loading classes and resources.
1462 * If not {@linkplain #setContextClassLoader set}, the default is the
1463 * {@code ClassLoader} context of the parent thread. The context
1464 * {@code ClassLoader} of the
1465 * primordial thread is typically set to the class loader used to load the
1466 * application.
1467 *
1468 *
1469 * @return the context {@code ClassLoader} for this thread, or {@code null}
1470 * indicating the system class loader (or, failing that, the
1471 * bootstrap class loader)
1472 *
1473 * @throws SecurityException
1474 * if a security manager is present, and the caller's class loader
1475 * is not {@code null} and is not the same as or an ancestor of the
1476 * context class loader, and the caller does not have the
1477 * {@link RuntimePermission}{@code ("getClassLoader")}
1478 *
1479 * @since 1.2
1480 */
1481 @CallerSensitive
1482 public ClassLoader getContextClassLoader() {
1483 if (contextClassLoader == null)
1484 return null;
1485 SecurityManager sm = System.getSecurityManager();
1486 if (sm != null) {
1487 ClassLoader.checkClassLoaderPermission(contextClassLoader,
1488 Reflection.getCallerClass());
1489 }
1490 return contextClassLoader;
1491 }
1492
1493 /**
1494 * Sets the context ClassLoader for this Thread. The context
1495 * ClassLoader can be set when a thread is created, and allows
1496 * the creator of the thread to provide the appropriate class loader,
1497 * through {@code getContextClassLoader}, to code running in the thread
1498 * when loading classes and resources.
1499 *
1500 * <p>If a security manager is present, its {@link
1501 * SecurityManager#checkPermission(java.security.Permission) checkPermission}
1502 * method is invoked with a {@link RuntimePermission RuntimePermission}{@code
1503 * ("setContextClassLoader")} permission to see if setting the context
1504 * ClassLoader is permitted.
1505 *
1506 * @param cl
1507 * the context ClassLoader for this Thread, or null indicating the
1508 * system class loader (or, failing that, the bootstrap class loader)
1509 *
1510 * @throws SecurityException
1511 * if the current thread cannot set the context ClassLoader
1512 *
1513 * @since 1.2
1514 */
1515 public void setContextClassLoader(ClassLoader cl) {
1516 SecurityManager sm = System.getSecurityManager();
1517 if (sm != null) {
1518 sm.checkPermission(new RuntimePermission("setContextClassLoader"));
1519 }
1520 contextClassLoader = cl;
1521 }
1522
1523 /**
1524 * Returns {@code true} if and only if the current thread holds the
1525 * monitor lock on the specified object.
1526 *
1527 * <p>This method is designed to allow a program to assert that
1528 * the current thread already holds a specified lock:
1529 * <pre>
1530 * assert Thread.holdsLock(obj);
1531 * </pre>
1532 *
1533 * @param obj the object on which to test lock ownership
1534 * @throws NullPointerException if obj is {@code null}
1535 * @return {@code true} if the current thread holds the monitor lock on
1536 * the specified object.
1537 * @since 1.4
1538 */
1539 public static native boolean holdsLock(Object obj);
1540
1541 private static final StackTraceElement[] EMPTY_STACK_TRACE
1542 = new StackTraceElement[0];
1543
1544 /**
1545 * Returns an array of stack trace elements representing the stack dump
1546 * of this thread. This method will return a zero-length array if
1547 * this thread has not started, has started but has not yet been
1548 * scheduled to run by the system, or has terminated.
1549 * If the returned array is of non-zero length then the first element of
1550 * the array represents the top of the stack, which is the most recent
1551 * method invocation in the sequence. The last element of the array
1552 * represents the bottom of the stack, which is the least recent method
1553 * invocation in the sequence.
1554 *
1555 * <p>If there is a security manager, and this thread is not
1556 * the current thread, then the security manager's
1557 * {@code checkPermission} method is called with a
1558 * {@code RuntimePermission("getStackTrace")} permission
1559 * to see if it's ok to get the stack trace.
1560 *
1561 * <p>Some virtual machines may, under some circumstances, omit one
1562 * or more stack frames from the stack trace. In the extreme case,
1563 * a virtual machine that has no stack trace information concerning
1564 * this thread is permitted to return a zero-length array from this
1565 * method.
1566 *
1567 * @return an array of {@code StackTraceElement},
1568 * each represents one stack frame.
1569 *
1570 * @throws SecurityException
1571 * if a security manager exists and its
1572 * {@code checkPermission} method doesn't allow
1573 * getting the stack trace of thread.
1574 * @see SecurityManager#checkPermission
1575 * @see RuntimePermission
1576 * @see Throwable#getStackTrace
1577 *
1578 * @since 1.5
1579 */
1580 public StackTraceElement[] getStackTrace() {
1581 if (this != Thread.currentThread()) {
1582 // check for getStackTrace permission
1583 SecurityManager security = System.getSecurityManager();
1584 if (security != null) {
1585 security.checkPermission(
1586 SecurityConstants.GET_STACK_TRACE_PERMISSION);
1587 }
1588 // optimization so we do not call into the vm for threads that
1589 // have not yet started or have terminated
1590 if (!isAlive()) {
1591 return EMPTY_STACK_TRACE;
1592 }
1593 StackTraceElement[][] stackTraceArray = dumpThreads(new Thread[] {this});
1594 StackTraceElement[] stackTrace = stackTraceArray[0];
1595 // a thread that was alive during the previous isAlive call may have
1596 // since terminated, therefore not having a stacktrace.
1597 if (stackTrace == null) {
1598 stackTrace = EMPTY_STACK_TRACE;
1599 }
1600 return stackTrace;
1601 } else {
1602 return (new Exception()).getStackTrace();
1603 }
1604 }
1605
1606 /**
1607 * Returns a map of stack traces for all live threads.
1608 * The map keys are threads and each map value is an array of
1609 * {@code StackTraceElement} that represents the stack dump
1610 * of the corresponding {@code Thread}.
1611 * The returned stack traces are in the format specified for
1612 * the {@link #getStackTrace getStackTrace} method.
1613 *
1614 * <p>The threads may be executing while this method is called.
1615 * The stack trace of each thread only represents a snapshot and
1616 * each stack trace may be obtained at different time. A zero-length
1617 * array will be returned in the map value if the virtual machine has
1618 * no stack trace information about a thread.
1619 *
1620 * <p>If there is a security manager, then the security manager's
1621 * {@code checkPermission} method is called with a
1622 * {@code RuntimePermission("getStackTrace")} permission as well as
1623 * {@code RuntimePermission("modifyThreadGroup")} permission
1624 * to see if it is ok to get the stack trace of all threads.
1625 *
1626 * @return a {@code Map} from {@code Thread} to an array of
1627 * {@code StackTraceElement} that represents the stack trace of
1628 * the corresponding thread.
1629 *
1630 * @throws SecurityException
1631 * if a security manager exists and its
1632 * {@code checkPermission} method doesn't allow
1633 * getting the stack trace of thread.
1634 * @see #getStackTrace
1635 * @see SecurityManager#checkPermission
1636 * @see RuntimePermission
1637 * @see Throwable#getStackTrace
1638 *
1639 * @since 1.5
1640 */
1641 public static Map<Thread, StackTraceElement[]> getAllStackTraces() {
1642 // check for getStackTrace permission
1643 SecurityManager security = System.getSecurityManager();
1644 if (security != null) {
1645 security.checkPermission(
1646 SecurityConstants.GET_STACK_TRACE_PERMISSION);
1647 security.checkPermission(
1648 SecurityConstants.MODIFY_THREADGROUP_PERMISSION);
1649 }
1650
1651 // Get a snapshot of the list of all threads
1652 Thread[] threads = getThreads();
1653 StackTraceElement[][] traces = dumpThreads(threads);
1654 Map<Thread, StackTraceElement[]> m = new HashMap<>(threads.length);
1655 for (int i = 0; i < threads.length; i++) {
1656 StackTraceElement[] stackTrace = traces[i];
1657 if (stackTrace != null) {
1658 m.put(threads[i], stackTrace);
1659 }
1660 // else terminated so we don't put it in the map
1661 }
1662 return m;
1663 }
1664
1665 /** cache of subclass security audit results */
1666 /* Replace with ConcurrentReferenceHashMap when/if it appears in a future
1667 * release */
1668 private static class Caches {
1669 /** cache of subclass security audit results */
1670 static final ConcurrentMap<WeakClassKey,Boolean> subclassAudits =
1671 new ConcurrentHashMap<>();
1672
1673 /** queue for WeakReferences to audited subclasses */
1674 static final ReferenceQueue<Class<?>> subclassAuditsQueue =
1675 new ReferenceQueue<>();
1676 }
1677
1678 /**
1679 * Verifies that this (possibly subclass) instance can be constructed
1680 * without violating security constraints: the subclass must not override
1681 * security-sensitive non-final methods, or else the
1682 * "enableContextClassLoaderOverride" RuntimePermission is checked.
1683 */
1684 private static boolean isCCLOverridden(Class<?> cl) {
1685 if (cl == Thread.class)
1686 return false;
1687
1688 processQueue(Caches.subclassAuditsQueue, Caches.subclassAudits);
1689 WeakClassKey key = new WeakClassKey(cl, Caches.subclassAuditsQueue);
1690 Boolean result = Caches.subclassAudits.get(key);
1691 if (result == null) {
1692 result = Boolean.valueOf(auditSubclass(cl));
1693 Caches.subclassAudits.putIfAbsent(key, result);
1694 }
1695
1696 return result.booleanValue();
1697 }
1698
1699 /**
1700 * Performs reflective checks on given subclass to verify that it doesn't
1701 * override security-sensitive non-final methods. Returns true if the
1702 * subclass overrides any of the methods, false otherwise.
1703 */
1704 private static boolean auditSubclass(final Class<?> subcl) {
1705 Boolean result = AccessController.doPrivileged(
1706 new PrivilegedAction<>() {
1707 public Boolean run() {
1708 for (Class<?> cl = subcl;
1709 cl != Thread.class;
1710 cl = cl.getSuperclass())
1711 {
1712 try {
1713 cl.getDeclaredMethod("getContextClassLoader", new Class<?>[0]);
1714 return Boolean.TRUE;
1715 } catch (NoSuchMethodException ex) {
1716 }
1717 try {
1718 Class<?>[] params = {ClassLoader.class};
1719 cl.getDeclaredMethod("setContextClassLoader", params);
1720 return Boolean.TRUE;
1721 } catch (NoSuchMethodException ex) {
1722 }
1723 }
1724 return Boolean.FALSE;
1725 }
1726 }
1727 );
1728 return result.booleanValue();
1729 }
1730
1731 private static native StackTraceElement[][] dumpThreads(Thread[] threads);
1732 private static native Thread[] getThreads();
1733
1734 /**
1735 * Returns the identifier of this Thread. The thread ID is a positive
1736 * {@code long} number generated when this thread was created.
1737 * The thread ID is unique and remains unchanged during its lifetime.
1738 * When a thread is terminated, this thread ID may be reused.
1739 *
1740 * @return this thread's ID.
1741 * @since 1.5
1742 */
1743 public long getId() {
1744 return tid;
1745 }
1746
1747 /**
1748 * A thread state. A thread can be in one of the following states:
1749 * <ul>
1750 * <li>{@link #NEW}<br>
1751 * A thread that has not yet started is in this state.
1752 * </li>
1753 * <li>{@link #RUNNABLE}<br>
1754 * A thread executing in the Java virtual machine is in this state.
1755 * </li>
1756 * <li>{@link #BLOCKED}<br>
1757 * A thread that is blocked waiting for a monitor lock
1758 * is in this state.
1759 * </li>
1760 * <li>{@link #WAITING}<br>
1761 * A thread that is waiting indefinitely for another thread to
1762 * perform a particular action is in this state.
1763 * </li>
1764 * <li>{@link #TIMED_WAITING}<br>
1765 * A thread that is waiting for another thread to perform an action
1766 * for up to a specified waiting time is in this state.
1767 * </li>
1768 * <li>{@link #TERMINATED}<br>
1769 * A thread that has exited is in this state.
1770 * </li>
1771 * </ul>
1772 *
1773 * <p>
1774 * A thread can be in only one state at a given point in time.
1775 * These states are virtual machine states which do not reflect
1776 * any operating system thread states.
1777 *
1778 * @since 1.5
1779 * @see #getState
1780 */
1781 public enum State {
1782 /**
1783 * Thread state for a thread which has not yet started.
1784 */
1785 NEW,
1786
1787 /**
1788 * Thread state for a runnable thread. A thread in the runnable
1789 * state is executing in the Java virtual machine but it may
1790 * be waiting for other resources from the operating system
1791 * such as processor.
1792 */
1793 RUNNABLE,
1794
1795 /**
1796 * Thread state for a thread blocked waiting for a monitor lock.
1797 * A thread in the blocked state is waiting for a monitor lock
1798 * to enter a synchronized block/method or
1799 * reenter a synchronized block/method after calling
1800 * {@link Object#wait() Object.wait}.
1801 */
1802 BLOCKED,
1803
1804 /**
1805 * Thread state for a waiting thread.
1806 * A thread is in the waiting state due to calling one of the
1807 * following methods:
1808 * <ul>
1809 * <li>{@link Object#wait() Object.wait} with no timeout</li>
1810 * <li>{@link #join() Thread.join} with no timeout</li>
1811 * <li>{@link LockSupport#park() LockSupport.park}</li>
1812 * </ul>
1813 *
1814 * <p>A thread in the waiting state is waiting for another thread to
1815 * perform a particular action.
1816 *
1817 * For example, a thread that has called {@code Object.wait()}
1818 * on an object is waiting for another thread to call
1819 * {@code Object.notify()} or {@code Object.notifyAll()} on
1820 * that object. A thread that has called {@code Thread.join()}
1821 * is waiting for a specified thread to terminate.
1822 */
1823 WAITING,
1824
1825 /**
1826 * Thread state for a waiting thread with a specified waiting time.
1827 * A thread is in the timed waiting state due to calling one of
1828 * the following methods with a specified positive waiting time:
1829 * <ul>
1830 * <li>{@link #sleep Thread.sleep}</li>
1831 * <li>{@link Object#wait(long) Object.wait} with timeout</li>
1832 * <li>{@link #join(long) Thread.join} with timeout</li>
1833 * <li>{@link LockSupport#parkNanos LockSupport.parkNanos}</li>
1834 * <li>{@link LockSupport#parkUntil LockSupport.parkUntil}</li>
1835 * </ul>
1836 */
1837 TIMED_WAITING,
1838
1839 /**
1840 * Thread state for a terminated thread.
1841 * The thread has completed execution.
1842 */
1843 TERMINATED;
1844 }
1845
1846 /**
1847 * Returns the state of this thread.
1848 * This method is designed for use in monitoring of the system state,
1849 * not for synchronization control.
1850 *
1851 * @return this thread's state.
1852 * @since 1.5
1853 */
1854 public State getState() {
1855 // get current thread state
1856 return jdk.internal.misc.VM.toThreadState(threadStatus);
1857 }
1858
1859 // Added in JSR-166
1860
1861 /**
1862 * Interface for handlers invoked when a {@code Thread} abruptly
1863 * terminates due to an uncaught exception.
1864 * <p>When a thread is about to terminate due to an uncaught exception
1865 * the Java Virtual Machine will query the thread for its
1866 * {@code UncaughtExceptionHandler} using
1867 * {@link #getUncaughtExceptionHandler} and will invoke the handler's
1868 * {@code uncaughtException} method, passing the thread and the
1869 * exception as arguments.
1870 * If a thread has not had its {@code UncaughtExceptionHandler}
1871 * explicitly set, then its {@code ThreadGroup} object acts as its
1872 * {@code UncaughtExceptionHandler}. If the {@code ThreadGroup} object
1873 * has no
1874 * special requirements for dealing with the exception, it can forward
1875 * the invocation to the {@linkplain #getDefaultUncaughtExceptionHandler
1876 * default uncaught exception handler}.
1877 *
1878 * @see #setDefaultUncaughtExceptionHandler
1879 * @see #setUncaughtExceptionHandler
1880 * @see ThreadGroup#uncaughtException
1881 * @since 1.5
1882 */
1883 @FunctionalInterface
1884 public interface UncaughtExceptionHandler {
1885 /**
1886 * Method invoked when the given thread terminates due to the
1887 * given uncaught exception.
1888 * <p>Any exception thrown by this method will be ignored by the
1889 * Java Virtual Machine.
1890 * @param t the thread
1891 * @param e the exception
1892 */
1893 void uncaughtException(Thread t, Throwable e);
1894 }
1895
1896 // null unless explicitly set
1897 private volatile UncaughtExceptionHandler uncaughtExceptionHandler;
1898
1899 // null unless explicitly set
1900 private static volatile UncaughtExceptionHandler defaultUncaughtExceptionHandler;
1901
1902 /**
1903 * Set the default handler invoked when a thread abruptly terminates
1904 * due to an uncaught exception, and no other handler has been defined
1905 * for that thread.
1906 *
1907 * <p>Uncaught exception handling is controlled first by the thread, then
1908 * by the thread's {@link ThreadGroup} object and finally by the default
1909 * uncaught exception handler. If the thread does not have an explicit
1910 * uncaught exception handler set, and the thread's thread group
1911 * (including parent thread groups) does not specialize its
1912 * {@code uncaughtException} method, then the default handler's
1913 * {@code uncaughtException} method will be invoked.
1914 * <p>By setting the default uncaught exception handler, an application
1915 * can change the way in which uncaught exceptions are handled (such as
1916 * logging to a specific device, or file) for those threads that would
1917 * already accept whatever "default" behavior the system
1918 * provided.
1919 *
1920 * <p>Note that the default uncaught exception handler should not usually
1921 * defer to the thread's {@code ThreadGroup} object, as that could cause
1922 * infinite recursion.
1923 *
1924 * @param eh the object to use as the default uncaught exception handler.
1925 * If {@code null} then there is no default handler.
1926 *
1927 * @throws SecurityException if a security manager is present and it denies
1928 * {@link RuntimePermission}{@code ("setDefaultUncaughtExceptionHandler")}
1929 *
1930 * @see #setUncaughtExceptionHandler
1931 * @see #getUncaughtExceptionHandler
1932 * @see ThreadGroup#uncaughtException
1933 * @since 1.5
1934 */
1935 public static void setDefaultUncaughtExceptionHandler(UncaughtExceptionHandler eh) {
1936 SecurityManager sm = System.getSecurityManager();
1937 if (sm != null) {
1938 sm.checkPermission(
1939 new RuntimePermission("setDefaultUncaughtExceptionHandler")
1940 );
1941 }
1942
1943 defaultUncaughtExceptionHandler = eh;
1944 }
1945
1946 /**
1947 * Returns the default handler invoked when a thread abruptly terminates
1948 * due to an uncaught exception. If the returned value is {@code null},
1949 * there is no default.
1950 * @since 1.5
1951 * @see #setDefaultUncaughtExceptionHandler
1952 * @return the default uncaught exception handler for all threads
1953 */
1954 public static UncaughtExceptionHandler getDefaultUncaughtExceptionHandler(){
1955 return defaultUncaughtExceptionHandler;
1956 }
1957
1958 /**
1959 * Returns the handler invoked when this thread abruptly terminates
1960 * due to an uncaught exception. If this thread has not had an
1961 * uncaught exception handler explicitly set then this thread's
1962 * {@code ThreadGroup} object is returned, unless this thread
1963 * has terminated, in which case {@code null} is returned.
1964 * @since 1.5
1965 * @return the uncaught exception handler for this thread
1966 */
1967 public UncaughtExceptionHandler getUncaughtExceptionHandler() {
1968 return uncaughtExceptionHandler != null ?
1969 uncaughtExceptionHandler : group;
1970 }
1971
1972 /**
1973 * Set the handler invoked when this thread abruptly terminates
1974 * due to an uncaught exception.
1975 * <p>A thread can take full control of how it responds to uncaught
1976 * exceptions by having its uncaught exception handler explicitly set.
1977 * If no such handler is set then the thread's {@code ThreadGroup}
1978 * object acts as its handler.
1979 * @param eh the object to use as this thread's uncaught exception
1980 * handler. If {@code null} then this thread has no explicit handler.
1981 * @throws SecurityException if the current thread is not allowed to
1982 * modify this thread.
1983 * @see #setDefaultUncaughtExceptionHandler
1984 * @see ThreadGroup#uncaughtException
1985 * @since 1.5
1986 */
1987 public void setUncaughtExceptionHandler(UncaughtExceptionHandler eh) {
1988 checkAccess();
1989 uncaughtExceptionHandler = eh;
1990 }
1991
1992 /**
1993 * Dispatch an uncaught exception to the handler. This method is
1994 * intended to be called only by the JVM.
1995 */
1996 private void dispatchUncaughtException(Throwable e) {
1997 getUncaughtExceptionHandler().uncaughtException(this, e);
1998 }
1999
2000 /**
2001 * Removes from the specified map any keys that have been enqueued
2002 * on the specified reference queue.
2003 */
2004 static void processQueue(ReferenceQueue<Class<?>> queue,
2005 ConcurrentMap<? extends
2006 WeakReference<Class<?>>, ?> map)
2007 {
2008 Reference<? extends Class<?>> ref;
2009 while((ref = queue.poll()) != null) {
2010 map.remove(ref);
2011 }
2012 }
2013
2014 /**
2015 * Weak key for Class objects.
2016 **/
2017 static class WeakClassKey extends WeakReference<Class<?>> {
2018 /**
2019 * saved value of the referent's identity hash code, to maintain
2020 * a consistent hash code after the referent has been cleared
2021 */
2022 private final int hash;
2023
2024 /**
2025 * Create a new WeakClassKey to the given object, registered
2026 * with a queue.
2027 */
2028 WeakClassKey(Class<?> cl, ReferenceQueue<Class<?>> refQueue) {
2029 super(cl, refQueue);
2030 hash = System.identityHashCode(cl);
2031 }
2032
2033 /**
2034 * Returns the identity hash code of the original referent.
2035 */
2036 @Override
2037 public int hashCode() {
2038 return hash;
2039 }
2040
2041 /**
2042 * Returns true if the given object is this identical
2043 * WeakClassKey instance, or, if this object's referent has not
2044 * been cleared, if the given object is another WeakClassKey
2045 * instance with the identical non-null referent as this one.
2046 */
2047 @Override
2048 public boolean equals(Object obj) {
2049 if (obj == this)
2050 return true;
2051
2052 if (obj instanceof WeakClassKey) {
2053 Object referent = get();
2054 return (referent != null) &&
2055 (referent == ((WeakClassKey) obj).get());
2056 } else {
2057 return false;
2058 }
2059 }
2060 }
2061
2062
2063 // The following three initially uninitialized fields are exclusively
2064 // managed by class java.util.concurrent.ThreadLocalRandom. These
2065 // fields are used to build the high-performance PRNGs in the
2066 // concurrent code, and we can not risk accidental false sharing.
2067 // Hence, the fields are isolated with @Contended.
2068
2069 /** The current seed for a ThreadLocalRandom */
2070 @jdk.internal.vm.annotation.Contended("tlr")
2071 long threadLocalRandomSeed;
2072
2073 /** Probe hash value; nonzero if threadLocalRandomSeed initialized */
2074 @jdk.internal.vm.annotation.Contended("tlr")
2075 int threadLocalRandomProbe;
2076
2077 /** Secondary seed isolated from public ThreadLocalRandom sequence */
2078 @jdk.internal.vm.annotation.Contended("tlr")
2079 int threadLocalRandomSecondarySeed;
2080
2081 /* Some private helper methods */
2082 private native void setPriority0(int newPriority);
2083 private native void stop0(Object o);
2084 private native void suspend0();
2085 private native void resume0();
2086 private native void interrupt0();
2087 private native void setNativeName(String name);
2088 }