1 /*
2 * Copyright (c) 1994, 2019, 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 /* Interrupt state of the thread - read/written directly by JVM */
158 private volatile boolean interrupted;
159
160 /* Fields reserved for exclusive use by the JVM */
161 private boolean stillborn = false;
162 private long eetop;
163
164 /* What will be run. */
165 private Runnable target;
166
167 /* The group of this thread */
168 private ThreadGroup group;
169
170 /* The context ClassLoader for this thread */
171 private ClassLoader contextClassLoader;
172
173 /* The inherited AccessControlContext of this thread */
174 private AccessControlContext inheritedAccessControlContext;
175
176 /* For autonumbering anonymous threads. */
177 private static int threadInitNumber;
178 private static synchronized int nextThreadNum() {
179 return threadInitNumber++;
180 }
181
182 /* ThreadLocal values pertaining to this thread. This map is maintained
183 * by the ThreadLocal class. */
184 ThreadLocal.ThreadLocalMap threadLocals = null;
185
186 /*
187 * InheritableThreadLocal values pertaining to this thread. This map is
188 * maintained by the InheritableThreadLocal class.
189 */
190 ThreadLocal.ThreadLocalMap inheritableThreadLocals = null;
191
192 /*
193 * The requested stack size for this thread, or 0 if the creator did
194 * not specify a stack size. It is up to the VM to do whatever it
195 * likes with this number; some VMs will ignore it.
196 */
197 private final long stackSize;
198
199 /*
200 * Thread ID
201 */
202 private final long tid;
203
204 /* For generating thread ID */
205 private static long threadSeqNumber;
206
207 private static synchronized long nextThreadID() {
208 return ++threadSeqNumber;
209 }
210
211 /*
212 * Java thread status for tools, default indicates thread 'not yet started'
213 */
214 private volatile int threadStatus;
215
216 /**
217 * The argument supplied to the current call to
218 * java.util.concurrent.locks.LockSupport.park.
219 * Set by (private) java.util.concurrent.locks.LockSupport.setBlocker
220 * Accessed using java.util.concurrent.locks.LockSupport.getBlocker
221 */
222 volatile Object parkBlocker;
223
224 /* The object in which this thread is blocked in an interruptible I/O
225 * operation, if any. The blocker's interrupt method should be invoked
226 * after setting this thread's interrupt status.
227 */
228 private volatile Interruptible blocker;
229 private final Object blockerLock = new Object();
230
231 /* Set the blocker field; invoked via jdk.internal.access.SharedSecrets
232 * from java.nio code
233 */
234 static void blockedOn(Interruptible b) {
235 Thread me = Thread.currentThread();
236 synchronized (me.blockerLock) {
237 me.blocker = b;
238 }
239 }
240
241 /**
242 * The minimum priority that a thread can have.
243 */
244 public static final int MIN_PRIORITY = 1;
245
246 /**
247 * The default priority that is assigned to a thread.
248 */
249 public static final int NORM_PRIORITY = 5;
250
251 /**
252 * The maximum priority that a thread can have.
253 */
254 public static final int MAX_PRIORITY = 10;
255
256 /**
257 * Returns a reference to the currently executing thread object.
258 *
259 * @return the currently executing thread.
260 */
261 @HotSpotIntrinsicCandidate
262 public static native Thread currentThread();
263
264 /**
265 * A hint to the scheduler that the current thread is willing to yield
266 * its current use of a processor. The scheduler is free to ignore this
267 * hint.
268 *
269 * <p> Yield is a heuristic attempt to improve relative progression
270 * between threads that would otherwise over-utilise a CPU. Its use
271 * should be combined with detailed profiling and benchmarking to
272 * ensure that it actually has the desired effect.
273 *
274 * <p> It is rarely appropriate to use this method. It may be useful
275 * for debugging or testing purposes, where it may help to reproduce
276 * bugs due to race conditions. It may also be useful when designing
277 * concurrency control constructs such as the ones in the
278 * {@link java.util.concurrent.locks} package.
279 */
280 public static native void yield();
281
282 /**
283 * Causes the currently executing thread to sleep (temporarily cease
284 * execution) for the specified number of milliseconds, subject to
285 * the precision and accuracy of system timers and schedulers. The thread
286 * does not lose ownership of any monitors.
287 *
288 * @param millis
289 * the length of time to sleep in milliseconds
290 *
291 * @throws IllegalArgumentException
292 * if the value of {@code millis} is negative
293 *
294 * @throws InterruptedException
295 * if any thread has interrupted the current thread. The
296 * <i>interrupted status</i> of the current thread is
297 * cleared when this exception is thrown.
298 */
299 public static native void sleep(long millis) throws InterruptedException;
300
301 /**
302 * Causes the currently executing thread to sleep (temporarily cease
303 * execution) for the specified number of milliseconds plus the specified
304 * number of nanoseconds, subject to the precision and accuracy of system
305 * timers and schedulers. The thread does not lose ownership of any
306 * monitors.
307 *
308 * @param millis
309 * the length of time to sleep in milliseconds
310 *
311 * @param nanos
312 * {@code 0-999999} additional nanoseconds to sleep
313 *
314 * @throws IllegalArgumentException
315 * if the value of {@code millis} is negative, or the value of
316 * {@code nanos} is not in the range {@code 0-999999}
317 *
318 * @throws InterruptedException
319 * if any thread has interrupted the current thread. The
320 * <i>interrupted status</i> of the current thread is
321 * cleared when this exception is thrown.
322 */
323 public static void sleep(long millis, int nanos)
324 throws InterruptedException {
325 if (millis < 0) {
326 throw new IllegalArgumentException("timeout value is negative");
327 }
328
329 if (nanos < 0 || nanos > 999999) {
330 throw new IllegalArgumentException(
331 "nanosecond timeout value out of range");
332 }
333
334 if (nanos > 0 && millis < Long.MAX_VALUE) {
335 millis++;
336 }
337
338 sleep(millis);
339 }
340
341 /**
342 * Indicates that the caller is momentarily unable to progress, until the
343 * occurrence of one or more actions on the part of other activities. By
344 * invoking this method within each iteration of a spin-wait loop construct,
345 * the calling thread indicates to the runtime that it is busy-waiting.
346 * The runtime may take action to improve the performance of invoking
347 * spin-wait loop constructions.
348 *
349 * @apiNote
350 * As an example consider a method in a class that spins in a loop until
351 * some flag is set outside of that method. A call to the {@code onSpinWait}
352 * method should be placed inside the spin loop.
353 * <pre>{@code
354 * class EventHandler {
355 * volatile boolean eventNotificationNotReceived;
356 * void waitForEventAndHandleIt() {
357 * while ( eventNotificationNotReceived ) {
358 * java.lang.Thread.onSpinWait();
359 * }
360 * readAndProcessEvent();
361 * }
362 *
363 * void readAndProcessEvent() {
364 * // Read event from some source and process it
365 * . . .
366 * }
367 * }
368 * }</pre>
369 * <p>
370 * The code above would remain correct even if the {@code onSpinWait}
371 * method was not called at all. However on some architectures the Java
372 * Virtual Machine may issue the processor instructions to address such
373 * code patterns in a more beneficial way.
374 *
375 * @since 9
376 */
377 @HotSpotIntrinsicCandidate
378 public static void onSpinWait() {}
379
380 /**
381 * Initializes a Thread.
382 *
383 * @param g the Thread group
384 * @param target the object whose run() method gets called
385 * @param name the name of the new Thread
386 * @param stackSize the desired stack size for the new thread, or
387 * zero to indicate that this parameter is to be ignored.
388 * @param acc the AccessControlContext to inherit, or
389 * AccessController.getContext() if null
390 * @param inheritThreadLocals if {@code true}, inherit initial values for
391 * inheritable thread-locals from the constructing thread
392 */
393 private Thread(ThreadGroup g, Runnable target, String name,
394 long stackSize, AccessControlContext acc,
395 boolean inheritThreadLocals) {
396 if (name == null) {
397 throw new NullPointerException("name cannot be null");
398 }
399
400 this.name = name;
401
402 Thread parent = currentThread();
403 SecurityManager security = System.getSecurityManager();
404 if (g == null) {
405 /* Determine if it's an applet or not */
406
407 /* If there is a security manager, ask the security manager
408 what to do. */
409 if (security != null) {
410 g = security.getThreadGroup();
411 }
412
413 /* If the security manager doesn't have a strong opinion
414 on the matter, use the parent thread group. */
415 if (g == null) {
416 g = parent.getThreadGroup();
417 }
418 }
419
420 /* checkAccess regardless of whether or not threadgroup is
421 explicitly passed in. */
422 g.checkAccess();
423
424 /*
425 * Do we have the required permissions?
426 */
427 if (security != null) {
428 if (isCCLOverridden(getClass())) {
429 security.checkPermission(
430 SecurityConstants.SUBCLASS_IMPLEMENTATION_PERMISSION);
431 }
432 }
433
434 g.addUnstarted();
435
436 this.group = g;
437 this.daemon = parent.isDaemon();
438 this.priority = parent.getPriority();
439 if (security == null || isCCLOverridden(parent.getClass()))
440 this.contextClassLoader = parent.getContextClassLoader();
441 else
442 this.contextClassLoader = parent.contextClassLoader;
443 this.inheritedAccessControlContext =
444 acc != null ? acc : AccessController.getContext();
445 this.target = target;
446 setPriority(priority);
447 if (inheritThreadLocals && parent.inheritableThreadLocals != null)
448 this.inheritableThreadLocals =
449 ThreadLocal.createInheritedMap(parent.inheritableThreadLocals);
450 /* Stash the specified stack size in case the VM cares */
451 this.stackSize = stackSize;
452
453 /* Set thread ID */
454 this.tid = nextThreadID();
455 }
456
457 /**
458 * Throws CloneNotSupportedException as a Thread can not be meaningfully
459 * cloned. Construct a new Thread instead.
460 *
461 * @throws CloneNotSupportedException
462 * always
463 */
464 @Override
465 protected Object clone() throws CloneNotSupportedException {
466 throw new CloneNotSupportedException();
467 }
468
469 /**
470 * Allocates a new {@code Thread} object. This constructor has the same
471 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
472 * {@code (null, null, gname)}, where {@code gname} is a newly generated
473 * name. Automatically generated names are of the form
474 * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
475 */
476 public Thread() {
477 this(null, null, "Thread-" + nextThreadNum(), 0);
478 }
479
480 /**
481 * Allocates a new {@code Thread} object. This constructor has the same
482 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
483 * {@code (null, target, gname)}, where {@code gname} is a newly generated
484 * name. Automatically generated names are of the form
485 * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
486 *
487 * @param target
488 * the object whose {@code run} method is invoked when this thread
489 * is started. If {@code null}, this classes {@code run} method does
490 * nothing.
491 */
492 public Thread(Runnable target) {
493 this(null, target, "Thread-" + nextThreadNum(), 0);
494 }
495
496 /**
497 * Creates a new Thread that inherits the given AccessControlContext
498 * but thread-local variables are not inherited.
499 * This is not a public constructor.
500 */
501 Thread(Runnable target, AccessControlContext acc) {
502 this(null, target, "Thread-" + nextThreadNum(), 0, acc, false);
503 }
504
505 /**
506 * Allocates a new {@code Thread} object. This constructor has the same
507 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
508 * {@code (group, target, gname)} ,where {@code gname} is a newly generated
509 * name. Automatically generated names are of the form
510 * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
511 *
512 * @param group
513 * the thread group. If {@code null} and there is a security
514 * manager, the group is determined by {@linkplain
515 * SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
516 * If there is not a security manager or {@code
517 * SecurityManager.getThreadGroup()} returns {@code null}, the group
518 * is set to the current thread's thread group.
519 *
520 * @param target
521 * the object whose {@code run} method is invoked when this thread
522 * is started. If {@code null}, this thread's run method is invoked.
523 *
524 * @throws SecurityException
525 * if the current thread cannot create a thread in the specified
526 * thread group
527 */
528 public Thread(ThreadGroup group, Runnable target) {
529 this(group, target, "Thread-" + nextThreadNum(), 0);
530 }
531
532 /**
533 * Allocates a new {@code Thread} object. This constructor has the same
534 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
535 * {@code (null, null, name)}.
536 *
537 * @param name
538 * the name of the new thread
539 */
540 public Thread(String name) {
541 this(null, null, name, 0);
542 }
543
544 /**
545 * Allocates a new {@code Thread} object. This constructor has the same
546 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
547 * {@code (group, null, name)}.
548 *
549 * @param group
550 * the thread group. If {@code null} and there is a security
551 * manager, the group is determined by {@linkplain
552 * SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
553 * If there is not a security manager or {@code
554 * SecurityManager.getThreadGroup()} returns {@code null}, the group
555 * is set to the current thread's thread group.
556 *
557 * @param name
558 * the name of the new thread
559 *
560 * @throws SecurityException
561 * if the current thread cannot create a thread in the specified
562 * thread group
563 */
564 public Thread(ThreadGroup group, String name) {
565 this(group, null, name, 0);
566 }
567
568 /**
569 * Allocates a new {@code Thread} object. This constructor has the same
570 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
571 * {@code (null, target, name)}.
572 *
573 * @param target
574 * the object whose {@code run} method is invoked when this thread
575 * is started. If {@code null}, this thread's run method is invoked.
576 *
577 * @param name
578 * the name of the new thread
579 */
580 public Thread(Runnable target, String name) {
581 this(null, target, name, 0);
582 }
583
584 /**
585 * Allocates a new {@code Thread} object so that it has {@code target}
586 * as its run object, has the specified {@code name} as its name,
587 * and belongs to the thread group referred to by {@code group}.
588 *
589 * <p>If there is a security manager, its
590 * {@link SecurityManager#checkAccess(ThreadGroup) checkAccess}
591 * method is invoked with the ThreadGroup as its argument.
592 *
593 * <p>In addition, its {@code checkPermission} method is invoked with
594 * the {@code RuntimePermission("enableContextClassLoaderOverride")}
595 * permission when invoked directly or indirectly by the constructor
596 * of a subclass which overrides the {@code getContextClassLoader}
597 * or {@code setContextClassLoader} methods.
598 *
599 * <p>The priority of the newly created thread is set equal to the
600 * priority of the thread creating it, that is, the currently running
601 * thread. The method {@linkplain #setPriority setPriority} may be
602 * used to change the priority to a new value.
603 *
604 * <p>The newly created thread is initially marked as being a daemon
605 * thread if and only if the thread creating it is currently marked
606 * as a daemon thread. The method {@linkplain #setDaemon setDaemon}
607 * may be used to change whether or not a thread is a daemon.
608 *
609 * @param group
610 * the thread group. If {@code null} and there is a security
611 * manager, the group is determined by {@linkplain
612 * SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
613 * If there is not a security manager or {@code
614 * SecurityManager.getThreadGroup()} returns {@code null}, the group
615 * is set to the current thread's thread group.
616 *
617 * @param target
618 * the object whose {@code run} method is invoked when this thread
619 * is started. If {@code null}, this thread's run method is invoked.
620 *
621 * @param name
622 * the name of the new thread
623 *
624 * @throws SecurityException
625 * if the current thread cannot create a thread in the specified
626 * thread group or cannot override the context class loader methods.
627 */
628 public Thread(ThreadGroup group, Runnable target, String name) {
629 this(group, target, name, 0);
630 }
631
632 /**
633 * Allocates a new {@code Thread} object so that it has {@code target}
634 * as its run object, has the specified {@code name} as its name,
635 * and belongs to the thread group referred to by {@code group}, and has
636 * the specified <i>stack size</i>.
637 *
638 * <p>This constructor is identical to {@link
639 * #Thread(ThreadGroup,Runnable,String)} with the exception of the fact
640 * that it allows the thread stack size to be specified. The stack size
641 * is the approximate number of bytes of address space that the virtual
642 * machine is to allocate for this thread's stack. <b>The effect of the
643 * {@code stackSize} parameter, if any, is highly platform dependent.</b>
644 *
645 * <p>On some platforms, specifying a higher value for the
646 * {@code stackSize} parameter may allow a thread to achieve greater
647 * recursion depth before throwing a {@link StackOverflowError}.
648 * Similarly, specifying a lower value may allow a greater number of
649 * threads to exist concurrently without throwing an {@link
650 * OutOfMemoryError} (or other internal error). The details of
651 * the relationship between the value of the {@code stackSize} parameter
652 * and the maximum recursion depth and concurrency level are
653 * platform-dependent. <b>On some platforms, the value of the
654 * {@code stackSize} parameter may have no effect whatsoever.</b>
655 *
656 * <p>The virtual machine is free to treat the {@code stackSize}
657 * parameter as a suggestion. If the specified value is unreasonably low
658 * for the platform, the virtual machine may instead use some
659 * platform-specific minimum value; if the specified value is unreasonably
660 * high, the virtual machine may instead use some platform-specific
661 * maximum. Likewise, the virtual machine is free to round the specified
662 * value up or down as it sees fit (or to ignore it completely).
663 *
664 * <p>Specifying a value of zero for the {@code stackSize} parameter will
665 * cause this constructor to behave exactly like the
666 * {@code Thread(ThreadGroup, Runnable, String)} constructor.
667 *
668 * <p><i>Due to the platform-dependent nature of the behavior of this
669 * constructor, extreme care should be exercised in its use.
670 * The thread stack size necessary to perform a given computation will
671 * likely vary from one JRE implementation to another. In light of this
672 * variation, careful tuning of the stack size parameter may be required,
673 * and the tuning may need to be repeated for each JRE implementation on
674 * which an application is to run.</i>
675 *
676 * <p>Implementation note: Java platform implementers are encouraged to
677 * document their implementation's behavior with respect to the
678 * {@code stackSize} parameter.
679 *
680 *
681 * @param group
682 * the thread group. If {@code null} and there is a security
683 * manager, the group is determined by {@linkplain
684 * SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
685 * If there is not a security manager or {@code
686 * SecurityManager.getThreadGroup()} returns {@code null}, the group
687 * is set to the current thread's thread group.
688 *
689 * @param target
690 * the object whose {@code run} method is invoked when this thread
691 * is started. If {@code null}, this thread's run method is invoked.
692 *
693 * @param name
694 * the name of the new thread
695 *
696 * @param stackSize
697 * the desired stack size for the new thread, or zero to indicate
698 * that this parameter is to be ignored.
699 *
700 * @throws SecurityException
701 * if the current thread cannot create a thread in the specified
702 * thread group
703 *
704 * @since 1.4
705 */
706 public Thread(ThreadGroup group, Runnable target, String name,
707 long stackSize) {
708 this(group, target, name, stackSize, null, true);
709 }
710
711 /**
712 * Allocates a new {@code Thread} object so that it has {@code target}
713 * as its run object, has the specified {@code name} as its name,
714 * belongs to the thread group referred to by {@code group}, has
715 * the specified {@code stackSize}, and inherits initial values for
716 * {@linkplain InheritableThreadLocal inheritable thread-local} variables
717 * if {@code inheritThreadLocals} is {@code true}.
718 *
719 * <p> This constructor is identical to {@link
720 * #Thread(ThreadGroup,Runnable,String,long)} with the added ability to
721 * suppress, or not, the inheriting of initial values for inheritable
722 * thread-local variables from the constructing thread. This allows for
723 * finer grain control over inheritable thread-locals. Care must be taken
724 * when passing a value of {@code false} for {@code inheritThreadLocals},
725 * as it may lead to unexpected behavior if the new thread executes code
726 * that expects a specific thread-local value to be inherited.
727 *
728 * <p> Specifying a value of {@code true} for the {@code inheritThreadLocals}
729 * parameter will cause this constructor to behave exactly like the
730 * {@code Thread(ThreadGroup, Runnable, String, long)} constructor.
731 *
732 * @param group
733 * the thread group. If {@code null} and there is a security
734 * manager, the group is determined by {@linkplain
735 * SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
736 * If there is not a security manager or {@code
737 * SecurityManager.getThreadGroup()} returns {@code null}, the group
738 * is set to the current thread's thread group.
739 *
740 * @param target
741 * the object whose {@code run} method is invoked when this thread
742 * is started. If {@code null}, this thread's run method is invoked.
743 *
744 * @param name
745 * the name of the new thread
746 *
747 * @param stackSize
748 * the desired stack size for the new thread, or zero to indicate
749 * that this parameter is to be ignored
750 *
751 * @param inheritThreadLocals
752 * if {@code true}, inherit initial values for inheritable
753 * thread-locals from the constructing thread, otherwise no initial
754 * values are inherited
755 *
756 * @throws SecurityException
757 * if the current thread cannot create a thread in the specified
758 * thread group
759 *
760 * @since 9
761 */
762 public Thread(ThreadGroup group, Runnable target, String name,
763 long stackSize, boolean inheritThreadLocals) {
764 this(group, target, name, stackSize, null, inheritThreadLocals);
765 }
766
767 /**
768 * Causes this thread to begin execution; the Java Virtual Machine
769 * calls the {@code run} method of this thread.
770 * <p>
771 * The result is that two threads are running concurrently: the
772 * current thread (which returns from the call to the
773 * {@code start} method) and the other thread (which executes its
774 * {@code run} method).
775 * <p>
776 * It is never legal to start a thread more than once.
777 * In particular, a thread may not be restarted once it has completed
778 * execution.
779 *
780 * @throws IllegalThreadStateException if the thread was already started.
781 * @see #run()
782 * @see #stop()
783 */
784 public synchronized void start() {
785 /**
786 * This method is not invoked for the main method thread or "system"
787 * group threads created/set up by the VM. Any new functionality added
788 * to this method in the future may have to also be added to the VM.
789 *
790 * A zero status value corresponds to state "NEW".
791 */
792 if (threadStatus != 0)
793 throw new IllegalThreadStateException();
794
795 /* Notify the group that this thread is about to be started
796 * so that it can be added to the group's list of threads
797 * and the group's unstarted count can be decremented. */
798 group.add(this);
799
800 boolean started = false;
801 try {
802 start0();
803 started = true;
804 } finally {
805 try {
806 if (!started) {
807 group.threadStartFailed(this);
808 }
809 } catch (Throwable ignore) {
810 /* do nothing. If start0 threw a Throwable then
811 it will be passed up the call stack */
812 }
813 }
814 }
815
816 private native void start0();
817
818 /**
819 * If this thread was constructed using a separate
820 * {@code Runnable} run object, then that
821 * {@code Runnable} object's {@code run} method is called;
822 * otherwise, this method does nothing and returns.
823 * <p>
824 * Subclasses of {@code Thread} should override this method.
825 *
826 * @see #start()
827 * @see #stop()
828 * @see #Thread(ThreadGroup, Runnable, String)
829 */
830 @Override
831 public void run() {
832 if (target != null) {
833 target.run();
834 }
835 }
836
837 /**
838 * This method is called by the system to give a Thread
839 * a chance to clean up before it actually exits.
840 */
841 private void exit() {
842 if (threadLocals != null && TerminatingThreadLocal.REGISTRY.isPresent()) {
843 TerminatingThreadLocal.threadTerminated();
844 }
845 if (group != null) {
846 group.threadTerminated(this);
847 group = null;
848 }
849 /* Aggressively null out all reference fields: see bug 4006245 */
850 target = null;
851 /* Speed the release of some of these resources */
852 threadLocals = null;
853 inheritableThreadLocals = null;
854 inheritedAccessControlContext = null;
855 blocker = null;
856 uncaughtExceptionHandler = null;
857 }
858
859 /**
860 * Forces the thread to stop executing.
861 * <p>
862 * If there is a security manager installed, its {@code checkAccess}
863 * method is called with {@code this}
864 * as its argument. This may result in a
865 * {@code SecurityException} being raised (in the current thread).
866 * <p>
867 * If this thread is different from the current thread (that is, the current
868 * thread is trying to stop a thread other than itself), the
869 * security manager's {@code checkPermission} method (with a
870 * {@code RuntimePermission("stopThread")} argument) is called in
871 * addition.
872 * Again, this may result in throwing a
873 * {@code SecurityException} (in the current thread).
874 * <p>
875 * The thread represented by this thread is forced to stop whatever
876 * it is doing abnormally and to throw a newly created
877 * {@code ThreadDeath} object as an exception.
878 * <p>
879 * It is permitted to stop a thread that has not yet been started.
880 * If the thread is eventually started, it immediately terminates.
881 * <p>
882 * An application should not normally try to catch
883 * {@code ThreadDeath} unless it must do some extraordinary
884 * cleanup operation (note that the throwing of
885 * {@code ThreadDeath} causes {@code finally} clauses of
886 * {@code try} statements to be executed before the thread
887 * officially dies). If a {@code catch} clause catches a
888 * {@code ThreadDeath} object, it is important to rethrow the
889 * object so that the thread actually dies.
890 * <p>
891 * The top-level error handler that reacts to otherwise uncaught
892 * exceptions does not print out a message or otherwise notify the
893 * application if the uncaught exception is an instance of
894 * {@code ThreadDeath}.
895 *
896 * @throws SecurityException if the current thread cannot
897 * modify this thread.
898 * @see #interrupt()
899 * @see #checkAccess()
900 * @see #run()
901 * @see #start()
902 * @see ThreadDeath
903 * @see ThreadGroup#uncaughtException(Thread,Throwable)
904 * @see SecurityManager#checkAccess(Thread)
905 * @see SecurityManager#checkPermission
906 * @deprecated This method is inherently unsafe. Stopping a thread with
907 * Thread.stop causes it to unlock all of the monitors that it
908 * has locked (as a natural consequence of the unchecked
909 * {@code ThreadDeath} exception propagating up the stack). If
910 * any of the objects previously protected by these monitors were in
911 * an inconsistent state, the damaged objects become visible to
912 * other threads, potentially resulting in arbitrary behavior. Many
913 * uses of {@code stop} should be replaced by code that simply
914 * modifies some variable to indicate that the target thread should
915 * stop running. The target thread should check this variable
916 * regularly, and return from its run method in an orderly fashion
917 * if the variable indicates that it is to stop running. If the
918 * target thread waits for long periods (on a condition variable,
919 * for example), the {@code interrupt} method should be used to
920 * interrupt the wait.
921 * For more information, see
922 * <a href="{@docRoot}/java.base/java/lang/doc-files/threadPrimitiveDeprecation.html">Why
923 * are Thread.stop, Thread.suspend and Thread.resume Deprecated?</a>.
924 */
925 @Deprecated(since="1.2")
926 public final void stop() {
927 SecurityManager security = System.getSecurityManager();
928 if (security != null) {
929 checkAccess();
930 if (this != Thread.currentThread()) {
931 security.checkPermission(SecurityConstants.STOP_THREAD_PERMISSION);
932 }
933 }
934 // A zero status value corresponds to "NEW", it can't change to
935 // not-NEW because we hold the lock.
936 if (threadStatus != 0) {
937 resume(); // Wake up thread if it was suspended; no-op otherwise
938 }
939
940 // The VM can handle all thread states
941 stop0(new ThreadDeath());
942 }
943
944 /**
945 * Interrupts this thread.
946 *
947 * <p> Unless the current thread is interrupting itself, which is
948 * always permitted, the {@link #checkAccess() checkAccess} method
949 * of this thread is invoked, which may cause a {@link
950 * SecurityException} to be thrown.
951 *
952 * <p> If this thread is blocked in an invocation of the {@link
953 * Object#wait() wait()}, {@link Object#wait(long) wait(long)}, or {@link
954 * Object#wait(long, int) wait(long, int)} methods of the {@link Object}
955 * class, or of the {@link #join()}, {@link #join(long)}, {@link
956 * #join(long, int)}, {@link #sleep(long)}, or {@link #sleep(long, int)},
957 * methods of this class, then its interrupt status will be cleared and it
958 * will receive an {@link InterruptedException}.
959 *
960 * <p> If this thread is blocked in an I/O operation upon an {@link
961 * java.nio.channels.InterruptibleChannel InterruptibleChannel}
962 * then the channel will be closed, the thread's interrupt
963 * status will be set, and the thread will receive a {@link
964 * java.nio.channels.ClosedByInterruptException}.
965 *
966 * <p> If this thread is blocked in a {@link java.nio.channels.Selector}
967 * then the thread's interrupt status will be set and it will return
968 * immediately from the selection operation, possibly with a non-zero
969 * value, just as if the selector's {@link
970 * java.nio.channels.Selector#wakeup wakeup} method were invoked.
971 *
972 * <p> If none of the previous conditions hold then this thread's interrupt
973 * status will be set. </p>
974 *
975 * <p> Interrupting a thread that is not alive need not have any effect.
976 *
977 * @implNote In the JDK Reference Implementation, interruption of a thread
978 * that is not alive still records that the interrupt request was made and
979 * will report it via {@link #interrupted} and {@link #isInterrupted()}.
980 *
981 * @throws SecurityException
982 * if the current thread cannot modify this thread
983 *
984 * @revised 6.0, 14
985 * @spec JSR-51
986 */
987 public void interrupt() {
988 if (this != Thread.currentThread()) {
989 checkAccess();
990
991 // thread may be blocked in an I/O operation
992 synchronized (blockerLock) {
993 Interruptible b = blocker;
994 if (b != null) {
995 interrupted = true;
996 interrupt0(); // inform VM of interrupt
997 b.interrupt(this);
998 return;
999 }
1000 }
1001 }
1002 interrupted = true;
1003 // inform VM of interrupt
1004 interrupt0();
1005 }
1006
1007 /**
1008 * Tests whether the current thread has been interrupted. The
1009 * <i>interrupted status</i> of the thread is cleared by this method. In
1010 * other words, if this method were to be called twice in succession, the
1011 * second call would return false (unless the current thread were
1012 * interrupted again, after the first call had cleared its interrupted
1013 * status and before the second call had examined it).
1014 *
1015 * @return {@code true} if the current thread has been interrupted;
1016 * {@code false} otherwise.
1017 * @see #isInterrupted()
1018 * @revised 6.0, 14
1019 */
1020 public static boolean interrupted() {
1021 Thread t = currentThread();
1022 boolean interrupted = t.interrupted;
1023 // We may have been interrupted the moment after we read the field,
1024 // so only clear the field if we saw that it was set and will return
1025 // true; otherwise we could lose an interrupt.
1026 if (interrupted) {
1027 t.interrupted = false;
1028 clearInterruptEvent();
1029 }
1030 return interrupted;
1031 }
1032
1033 /**
1034 * Tests whether this thread has been interrupted. The <i>interrupted
1035 * status</i> of the thread is unaffected by this method.
1036 *
1037 * @return {@code true} if this thread has been interrupted;
1038 * {@code false} otherwise.
1039 * @see #interrupted()
1040 * @revised 6.0, 14
1041 */
1042 public boolean isInterrupted() {
1043 return interrupted;
1044 }
1045
1046 /**
1047 * Tests if this thread is alive. A thread is alive if it has
1048 * been started and has not yet died.
1049 *
1050 * @return {@code true} if this thread is alive;
1051 * {@code false} otherwise.
1052 */
1053 public final native boolean isAlive();
1054
1055 /**
1056 * Suspends this thread.
1057 * <p>
1058 * First, the {@code checkAccess} method of this thread is called
1059 * with no arguments. This may result in throwing a
1060 * {@code SecurityException }(in the current thread).
1061 * <p>
1062 * If the thread is alive, it is suspended and makes no further
1063 * progress unless and until it is resumed.
1064 *
1065 * @throws SecurityException if the current thread cannot modify
1066 * this thread.
1067 * @see #checkAccess
1068 * @deprecated This method has been deprecated, as it is
1069 * inherently deadlock-prone. If the target thread holds a lock on the
1070 * monitor protecting a critical system resource when it is suspended, no
1071 * thread can access this resource until the target thread is resumed. If
1072 * the thread that would resume the target thread attempts to lock this
1073 * monitor prior to calling {@code resume}, deadlock results. Such
1074 * deadlocks typically manifest themselves as "frozen" processes.
1075 * For more information, see
1076 * <a href="{@docRoot}/java.base/java/lang/doc-files/threadPrimitiveDeprecation.html">Why
1077 * are Thread.stop, Thread.suspend and Thread.resume Deprecated?</a>.
1078 */
1079 @Deprecated(since="1.2", forRemoval=true)
1080 public final void suspend() {
1081 checkAccess();
1082 suspend0();
1083 }
1084
1085 /**
1086 * Resumes a suspended thread.
1087 * <p>
1088 * First, the {@code checkAccess} method of this thread is called
1089 * with no arguments. This may result in throwing a
1090 * {@code SecurityException} (in the current thread).
1091 * <p>
1092 * If the thread is alive but suspended, it is resumed and is
1093 * permitted to make progress in its execution.
1094 *
1095 * @throws SecurityException if the current thread cannot modify this
1096 * thread.
1097 * @see #checkAccess
1098 * @see #suspend()
1099 * @deprecated This method exists solely for use with {@link #suspend},
1100 * which has been deprecated because it is deadlock-prone.
1101 * For more information, see
1102 * <a href="{@docRoot}/java.base/java/lang/doc-files/threadPrimitiveDeprecation.html">Why
1103 * are Thread.stop, Thread.suspend and Thread.resume Deprecated?</a>.
1104 */
1105 @Deprecated(since="1.2", forRemoval=true)
1106 public final void resume() {
1107 checkAccess();
1108 resume0();
1109 }
1110
1111 /**
1112 * Changes the priority of this thread.
1113 * <p>
1114 * First the {@code checkAccess} method of this thread is called
1115 * with no arguments. This may result in throwing a {@code SecurityException}.
1116 * <p>
1117 * Otherwise, the priority of this thread is set to the smaller of
1118 * the specified {@code newPriority} and the maximum permitted
1119 * priority of the thread's thread group.
1120 *
1121 * @param newPriority priority to set this thread to
1122 * @throws IllegalArgumentException If the priority is not in the
1123 * range {@code MIN_PRIORITY} to
1124 * {@code MAX_PRIORITY}.
1125 * @throws SecurityException if the current thread cannot modify
1126 * this thread.
1127 * @see #getPriority
1128 * @see #checkAccess()
1129 * @see #getThreadGroup()
1130 * @see #MAX_PRIORITY
1131 * @see #MIN_PRIORITY
1132 * @see ThreadGroup#getMaxPriority()
1133 */
1134 public final void setPriority(int newPriority) {
1135 ThreadGroup g;
1136 checkAccess();
1137 if (newPriority > MAX_PRIORITY || newPriority < MIN_PRIORITY) {
1138 throw new IllegalArgumentException();
1139 }
1140 if((g = getThreadGroup()) != null) {
1141 if (newPriority > g.getMaxPriority()) {
1142 newPriority = g.getMaxPriority();
1143 }
1144 setPriority0(priority = newPriority);
1145 }
1146 }
1147
1148 /**
1149 * Returns this thread's priority.
1150 *
1151 * @return this thread's priority.
1152 * @see #setPriority
1153 */
1154 public final int getPriority() {
1155 return priority;
1156 }
1157
1158 /**
1159 * Changes the name of this thread to be equal to the argument {@code name}.
1160 * <p>
1161 * First the {@code checkAccess} method of this thread is called
1162 * with no arguments. This may result in throwing a
1163 * {@code SecurityException}.
1164 *
1165 * @param name the new name for this thread.
1166 * @throws SecurityException if the current thread cannot modify this
1167 * thread.
1168 * @see #getName
1169 * @see #checkAccess()
1170 */
1171 public final synchronized void setName(String name) {
1172 checkAccess();
1173 if (name == null) {
1174 throw new NullPointerException("name cannot be null");
1175 }
1176
1177 this.name = name;
1178 if (threadStatus != 0) {
1179 setNativeName(name);
1180 }
1181 }
1182
1183 /**
1184 * Returns this thread's name.
1185 *
1186 * @return this thread's name.
1187 * @see #setName(String)
1188 */
1189 public final String getName() {
1190 return name;
1191 }
1192
1193 /**
1194 * Returns the thread group to which this thread belongs.
1195 * This method returns null if this thread has died
1196 * (been stopped).
1197 *
1198 * @return this thread's thread group.
1199 */
1200 public final ThreadGroup getThreadGroup() {
1201 return group;
1202 }
1203
1204 /**
1205 * Returns an estimate of the number of active threads in the current
1206 * thread's {@linkplain java.lang.ThreadGroup thread group} and its
1207 * subgroups. Recursively iterates over all subgroups in the current
1208 * thread's thread group.
1209 *
1210 * <p> The value returned is only an estimate because the number of
1211 * threads may change dynamically while this method traverses internal
1212 * data structures, and might be affected by the presence of certain
1213 * system threads. This method is intended primarily for debugging
1214 * and monitoring purposes.
1215 *
1216 * @return an estimate of the number of active threads in the current
1217 * thread's thread group and in any other thread group that
1218 * has the current thread's thread group as an ancestor
1219 */
1220 public static int activeCount() {
1221 return currentThread().getThreadGroup().activeCount();
1222 }
1223
1224 /**
1225 * Copies into the specified array every active thread in the current
1226 * thread's thread group and its subgroups. This method simply
1227 * invokes the {@link java.lang.ThreadGroup#enumerate(Thread[])}
1228 * method of the current thread's thread group.
1229 *
1230 * <p> An application might use the {@linkplain #activeCount activeCount}
1231 * method to get an estimate of how big the array should be, however
1232 * <i>if the array is too short to hold all the threads, the extra threads
1233 * are silently ignored.</i> If it is critical to obtain every active
1234 * thread in the current thread's thread group and its subgroups, the
1235 * invoker should verify that the returned int value is strictly less
1236 * than the length of {@code tarray}.
1237 *
1238 * <p> Due to the inherent race condition in this method, it is recommended
1239 * that the method only be used for debugging and monitoring purposes.
1240 *
1241 * @param tarray
1242 * an array into which to put the list of threads
1243 *
1244 * @return the number of threads put into the array
1245 *
1246 * @throws SecurityException
1247 * if {@link java.lang.ThreadGroup#checkAccess} determines that
1248 * the current thread cannot access its thread group
1249 */
1250 public static int enumerate(Thread tarray[]) {
1251 return currentThread().getThreadGroup().enumerate(tarray);
1252 }
1253
1254 /**
1255 * Counts the number of stack frames in this thread. The thread must
1256 * be suspended.
1257 *
1258 * @return the number of stack frames in this thread.
1259 * @throws IllegalThreadStateException if this thread is not
1260 * suspended.
1261 * @deprecated The definition of this call depends on {@link #suspend},
1262 * which is deprecated. Further, the results of this call
1263 * were never well-defined.
1264 * This method is subject to removal in a future version of Java SE.
1265 * @see StackWalker
1266 */
1267 @Deprecated(since="1.2", forRemoval=true)
1268 public native int countStackFrames();
1269
1270 /**
1271 * Waits at most {@code millis} milliseconds for this thread to
1272 * die. A timeout of {@code 0} means to wait forever.
1273 *
1274 * <p> This implementation uses a loop of {@code this.wait} calls
1275 * conditioned on {@code this.isAlive}. As a thread terminates the
1276 * {@code this.notifyAll} method is invoked. It is recommended that
1277 * applications not use {@code wait}, {@code notify}, or
1278 * {@code notifyAll} on {@code Thread} instances.
1279 *
1280 * @param millis
1281 * the time to wait in milliseconds
1282 *
1283 * @throws IllegalArgumentException
1284 * if the value of {@code millis} is negative
1285 *
1286 * @throws InterruptedException
1287 * if any thread has interrupted the current thread. The
1288 * <i>interrupted status</i> of the current thread is
1289 * cleared when this exception is thrown.
1290 */
1291 public final synchronized void join(final long millis)
1292 throws InterruptedException {
1293 if (millis > 0) {
1294 if (isAlive()) {
1295 final long startTime = System.nanoTime();
1296 long delay = millis;
1297 do {
1298 wait(delay);
1299 } while (isAlive() && (delay = millis -
1300 TimeUnit.NANOSECONDS.toMillis(System.nanoTime() - startTime)) > 0);
1301 }
1302 } else if (millis == 0) {
1303 while (isAlive()) {
1304 wait(0);
1305 }
1306 } else {
1307 throw new IllegalArgumentException("timeout value is negative");
1308 }
1309 }
1310
1311 /**
1312 * Waits at most {@code millis} milliseconds plus
1313 * {@code nanos} nanoseconds for this thread to die.
1314 * If both arguments are {@code 0}, it means to wait forever.
1315 *
1316 * <p> This implementation uses a loop of {@code this.wait} calls
1317 * conditioned on {@code this.isAlive}. As a thread terminates the
1318 * {@code this.notifyAll} method is invoked. It is recommended that
1319 * applications not use {@code wait}, {@code notify}, or
1320 * {@code notifyAll} on {@code Thread} instances.
1321 *
1322 * @param millis
1323 * the time to wait in milliseconds
1324 *
1325 * @param nanos
1326 * {@code 0-999999} additional nanoseconds to wait
1327 *
1328 * @throws IllegalArgumentException
1329 * if the value of {@code millis} is negative, or the value
1330 * of {@code nanos} is not in the range {@code 0-999999}
1331 *
1332 * @throws InterruptedException
1333 * if any thread has interrupted the current thread. The
1334 * <i>interrupted status</i> of the current thread is
1335 * cleared when this exception is thrown.
1336 */
1337 public final synchronized void join(long millis, int nanos)
1338 throws InterruptedException {
1339
1340 if (millis < 0) {
1341 throw new IllegalArgumentException("timeout value is negative");
1342 }
1343
1344 if (nanos < 0 || nanos > 999999) {
1345 throw new IllegalArgumentException(
1346 "nanosecond timeout value out of range");
1347 }
1348
1349 if (nanos > 0 && millis < Long.MAX_VALUE) {
1350 millis++;
1351 }
1352
1353 join(millis);
1354 }
1355
1356 /**
1357 * Waits for this thread to die.
1358 *
1359 * <p> An invocation of this method behaves in exactly the same
1360 * way as the invocation
1361 *
1362 * <blockquote>
1363 * {@linkplain #join(long) join}{@code (0)}
1364 * </blockquote>
1365 *
1366 * @throws InterruptedException
1367 * if any thread has interrupted the current thread. The
1368 * <i>interrupted status</i> of the current thread is
1369 * cleared when this exception is thrown.
1370 */
1371 public final void join() throws InterruptedException {
1372 join(0);
1373 }
1374
1375 /**
1376 * Prints a stack trace of the current thread to the standard error stream.
1377 * This method is used only for debugging.
1378 */
1379 public static void dumpStack() {
1380 new Exception("Stack trace").printStackTrace();
1381 }
1382
1383 /**
1384 * Marks this thread as either a {@linkplain #isDaemon daemon} thread
1385 * or a user thread. The Java Virtual Machine exits when the only
1386 * threads running are all daemon threads.
1387 *
1388 * <p> This method must be invoked before the thread is started.
1389 *
1390 * @param on
1391 * if {@code true}, marks this thread as a daemon thread
1392 *
1393 * @throws IllegalThreadStateException
1394 * if this thread is {@linkplain #isAlive alive}
1395 *
1396 * @throws SecurityException
1397 * if {@link #checkAccess} determines that the current
1398 * thread cannot modify this thread
1399 */
1400 public final void setDaemon(boolean on) {
1401 checkAccess();
1402 if (isAlive()) {
1403 throw new IllegalThreadStateException();
1404 }
1405 daemon = on;
1406 }
1407
1408 /**
1409 * Tests if this thread is a daemon thread.
1410 *
1411 * @return {@code true} if this thread is a daemon thread;
1412 * {@code false} otherwise.
1413 * @see #setDaemon(boolean)
1414 */
1415 public final boolean isDaemon() {
1416 return daemon;
1417 }
1418
1419 /**
1420 * Determines if the currently running thread has permission to
1421 * modify this thread.
1422 * <p>
1423 * If there is a security manager, its {@code checkAccess} method
1424 * is called with this thread as its argument. This may result in
1425 * throwing a {@code SecurityException}.
1426 *
1427 * @throws SecurityException if the current thread is not allowed to
1428 * access this thread.
1429 * @see SecurityManager#checkAccess(Thread)
1430 */
1431 public final void checkAccess() {
1432 SecurityManager security = System.getSecurityManager();
1433 if (security != null) {
1434 security.checkAccess(this);
1435 }
1436 }
1437
1438 /**
1439 * Returns a string representation of this thread, including the
1440 * thread's name, priority, and thread group.
1441 *
1442 * @return a string representation of this thread.
1443 */
1444 public String toString() {
1445 ThreadGroup group = getThreadGroup();
1446 if (group != null) {
1447 return "Thread[" + getName() + "," + getPriority() + "," +
1448 group.getName() + "]";
1449 } else {
1450 return "Thread[" + getName() + "," + getPriority() + "," +
1451 "" + "]";
1452 }
1453 }
1454
1455 /**
1456 * Returns the context {@code ClassLoader} for this thread. The context
1457 * {@code ClassLoader} is provided by the creator of the thread for use
1458 * by code running in this thread when loading classes and resources.
1459 * If not {@linkplain #setContextClassLoader set}, the default is the
1460 * {@code ClassLoader} context of the parent thread. The context
1461 * {@code ClassLoader} of the
1462 * primordial thread is typically set to the class loader used to load the
1463 * application.
1464 *
1465 *
1466 * @return the context {@code ClassLoader} for this thread, or {@code null}
1467 * indicating the system class loader (or, failing that, the
1468 * bootstrap class loader)
1469 *
1470 * @throws SecurityException
1471 * if a security manager is present, and the caller's class loader
1472 * is not {@code null} and is not the same as or an ancestor of the
1473 * context class loader, and the caller does not have the
1474 * {@link RuntimePermission}{@code ("getClassLoader")}
1475 *
1476 * @since 1.2
1477 */
1478 @CallerSensitive
1479 public ClassLoader getContextClassLoader() {
1480 if (contextClassLoader == null)
1481 return null;
1482 SecurityManager sm = System.getSecurityManager();
1483 if (sm != null) {
1484 ClassLoader.checkClassLoaderPermission(contextClassLoader,
1485 Reflection.getCallerClass());
1486 }
1487 return contextClassLoader;
1488 }
1489
1490 /**
1491 * Sets the context ClassLoader for this Thread. The context
1492 * ClassLoader can be set when a thread is created, and allows
1493 * the creator of the thread to provide the appropriate class loader,
1494 * through {@code getContextClassLoader}, to code running in the thread
1495 * when loading classes and resources.
1496 *
1497 * <p>If a security manager is present, its {@link
1498 * SecurityManager#checkPermission(java.security.Permission) checkPermission}
1499 * method is invoked with a {@link RuntimePermission RuntimePermission}{@code
1500 * ("setContextClassLoader")} permission to see if setting the context
1501 * ClassLoader is permitted.
1502 *
1503 * @param cl
1504 * the context ClassLoader for this Thread, or null indicating the
1505 * system class loader (or, failing that, the bootstrap class loader)
1506 *
1507 * @throws SecurityException
1508 * if the current thread cannot set the context ClassLoader
1509 *
1510 * @since 1.2
1511 */
1512 public void setContextClassLoader(ClassLoader cl) {
1513 SecurityManager sm = System.getSecurityManager();
1514 if (sm != null) {
1515 sm.checkPermission(new RuntimePermission("setContextClassLoader"));
1516 }
1517 contextClassLoader = cl;
1518 }
1519
1520 /**
1521 * Returns {@code true} if and only if the current thread holds the
1522 * monitor lock on the specified object.
1523 *
1524 * <p>This method is designed to allow a program to assert that
1525 * the current thread already holds a specified lock:
1526 * <pre>
1527 * assert Thread.holdsLock(obj);
1528 * </pre>
1529 *
1530 * @param obj the object on which to test lock ownership
1531 * @throws NullPointerException if obj is {@code null}
1532 * @return {@code true} if the current thread holds the monitor lock on
1533 * the specified object.
1534 * @since 1.4
1535 */
1536 public static native boolean holdsLock(Object obj);
1537
1538 private static final StackTraceElement[] EMPTY_STACK_TRACE
1539 = new StackTraceElement[0];
1540
1541 /**
1542 * Returns an array of stack trace elements representing the stack dump
1543 * of this thread. This method will return a zero-length array if
1544 * this thread has not started, has started but has not yet been
1545 * scheduled to run by the system, or has terminated.
1546 * If the returned array is of non-zero length then the first element of
1547 * the array represents the top of the stack, which is the most recent
1548 * method invocation in the sequence. The last element of the array
1549 * represents the bottom of the stack, which is the least recent method
1550 * invocation in the sequence.
1551 *
1552 * <p>If there is a security manager, and this thread is not
1553 * the current thread, then the security manager's
1554 * {@code checkPermission} method is called with a
1555 * {@code RuntimePermission("getStackTrace")} permission
1556 * to see if it's ok to get the stack trace.
1557 *
1558 * <p>Some virtual machines may, under some circumstances, omit one
1559 * or more stack frames from the stack trace. In the extreme case,
1560 * a virtual machine that has no stack trace information concerning
1561 * this thread is permitted to return a zero-length array from this
1562 * method.
1563 *
1564 * @return an array of {@code StackTraceElement},
1565 * each represents one stack frame.
1566 *
1567 * @throws SecurityException
1568 * if a security manager exists and its
1569 * {@code checkPermission} method doesn't allow
1570 * getting the stack trace of thread.
1571 * @see SecurityManager#checkPermission
1572 * @see RuntimePermission
1573 * @see Throwable#getStackTrace
1574 *
1575 * @since 1.5
1576 */
1577 public StackTraceElement[] getStackTrace() {
1578 if (this != Thread.currentThread()) {
1579 // check for getStackTrace permission
1580 SecurityManager security = System.getSecurityManager();
1581 if (security != null) {
1582 security.checkPermission(
1583 SecurityConstants.GET_STACK_TRACE_PERMISSION);
1584 }
1585 // optimization so we do not call into the vm for threads that
1586 // have not yet started or have terminated
1587 if (!isAlive()) {
1588 return EMPTY_STACK_TRACE;
1589 }
1590 StackTraceElement[][] stackTraceArray = dumpThreads(new Thread[] {this});
1591 StackTraceElement[] stackTrace = stackTraceArray[0];
1592 // a thread that was alive during the previous isAlive call may have
1593 // since terminated, therefore not having a stacktrace.
1594 if (stackTrace == null) {
1595 stackTrace = EMPTY_STACK_TRACE;
1596 }
1597 return stackTrace;
1598 } else {
1599 return (new Exception()).getStackTrace();
1600 }
1601 }
1602
1603 /**
1604 * Returns a map of stack traces for all live threads.
1605 * The map keys are threads and each map value is an array of
1606 * {@code StackTraceElement} that represents the stack dump
1607 * of the corresponding {@code Thread}.
1608 * The returned stack traces are in the format specified for
1609 * the {@link #getStackTrace getStackTrace} method.
1610 *
1611 * <p>The threads may be executing while this method is called.
1612 * The stack trace of each thread only represents a snapshot and
1613 * each stack trace may be obtained at different time. A zero-length
1614 * array will be returned in the map value if the virtual machine has
1615 * no stack trace information about a thread.
1616 *
1617 * <p>If there is a security manager, then the security manager's
1618 * {@code checkPermission} method is called with a
1619 * {@code RuntimePermission("getStackTrace")} permission as well as
1620 * {@code RuntimePermission("modifyThreadGroup")} permission
1621 * to see if it is ok to get the stack trace of all threads.
1622 *
1623 * @return a {@code Map} from {@code Thread} to an array of
1624 * {@code StackTraceElement} that represents the stack trace of
1625 * the corresponding thread.
1626 *
1627 * @throws SecurityException
1628 * if a security manager exists and its
1629 * {@code checkPermission} method doesn't allow
1630 * getting the stack trace of thread.
1631 * @see #getStackTrace
1632 * @see SecurityManager#checkPermission
1633 * @see RuntimePermission
1634 * @see Throwable#getStackTrace
1635 *
1636 * @since 1.5
1637 */
1638 public static Map<Thread, StackTraceElement[]> getAllStackTraces() {
1639 // check for getStackTrace permission
1640 SecurityManager security = System.getSecurityManager();
1641 if (security != null) {
1642 security.checkPermission(
1643 SecurityConstants.GET_STACK_TRACE_PERMISSION);
1644 security.checkPermission(
1645 SecurityConstants.MODIFY_THREADGROUP_PERMISSION);
1646 }
1647
1648 // Get a snapshot of the list of all threads
1649 Thread[] threads = getThreads();
1650 StackTraceElement[][] traces = dumpThreads(threads);
1651 Map<Thread, StackTraceElement[]> m = new HashMap<>(threads.length);
1652 for (int i = 0; i < threads.length; i++) {
1653 StackTraceElement[] stackTrace = traces[i];
1654 if (stackTrace != null) {
1655 m.put(threads[i], stackTrace);
1656 }
1657 // else terminated so we don't put it in the map
1658 }
1659 return m;
1660 }
1661
1662 /** cache of subclass security audit results */
1663 /* Replace with ConcurrentReferenceHashMap when/if it appears in a future
1664 * release */
1665 private static class Caches {
1666 /** cache of subclass security audit results */
1667 static final ConcurrentMap<WeakClassKey,Boolean> subclassAudits =
1668 new ConcurrentHashMap<>();
1669
1670 /** queue for WeakReferences to audited subclasses */
1671 static final ReferenceQueue<Class<?>> subclassAuditsQueue =
1672 new ReferenceQueue<>();
1673 }
1674
1675 /**
1676 * Verifies that this (possibly subclass) instance can be constructed
1677 * without violating security constraints: the subclass must not override
1678 * security-sensitive non-final methods, or else the
1679 * "enableContextClassLoaderOverride" RuntimePermission is checked.
1680 */
1681 private static boolean isCCLOverridden(Class<?> cl) {
1682 if (cl == Thread.class)
1683 return false;
1684
1685 processQueue(Caches.subclassAuditsQueue, Caches.subclassAudits);
1686 WeakClassKey key = new WeakClassKey(cl, Caches.subclassAuditsQueue);
1687 Boolean result = Caches.subclassAudits.get(key);
1688 if (result == null) {
1689 result = Boolean.valueOf(auditSubclass(cl));
1690 Caches.subclassAudits.putIfAbsent(key, result);
1691 }
1692
1693 return result.booleanValue();
1694 }
1695
1696 /**
1697 * Performs reflective checks on given subclass to verify that it doesn't
1698 * override security-sensitive non-final methods. Returns true if the
1699 * subclass overrides any of the methods, false otherwise.
1700 */
1701 private static boolean auditSubclass(final Class<?> subcl) {
1702 Boolean result = AccessController.doPrivileged(
1703 new PrivilegedAction<>() {
1704 public Boolean run() {
1705 for (Class<?> cl = subcl;
1706 cl != Thread.class;
1707 cl = cl.getSuperclass())
1708 {
1709 try {
1710 cl.getDeclaredMethod("getContextClassLoader", new Class<?>[0]);
1711 return Boolean.TRUE;
1712 } catch (NoSuchMethodException ex) {
1713 }
1714 try {
1715 Class<?>[] params = {ClassLoader.class};
1716 cl.getDeclaredMethod("setContextClassLoader", params);
1717 return Boolean.TRUE;
1718 } catch (NoSuchMethodException ex) {
1719 }
1720 }
1721 return Boolean.FALSE;
1722 }
1723 }
1724 );
1725 return result.booleanValue();
1726 }
1727
1728 private static native StackTraceElement[][] dumpThreads(Thread[] threads);
1729 private static native Thread[] getThreads();
1730
1731 /**
1732 * Returns the identifier of this Thread. The thread ID is a positive
1733 * {@code long} number generated when this thread was created.
1734 * The thread ID is unique and remains unchanged during its lifetime.
1735 * When a thread is terminated, this thread ID may be reused.
1736 *
1737 * @return this thread's ID.
1738 * @since 1.5
1739 */
1740 public long getId() {
1741 return tid;
1742 }
1743
1744 /**
1745 * A thread state. A thread can be in one of the following states:
1746 * <ul>
1747 * <li>{@link #NEW}<br>
1748 * A thread that has not yet started is in this state.
1749 * </li>
1750 * <li>{@link #RUNNABLE}<br>
1751 * A thread executing in the Java virtual machine is in this state.
1752 * </li>
1753 * <li>{@link #BLOCKED}<br>
1754 * A thread that is blocked waiting for a monitor lock
1755 * is in this state.
1756 * </li>
1757 * <li>{@link #WAITING}<br>
1758 * A thread that is waiting indefinitely for another thread to
1759 * perform a particular action is in this state.
1760 * </li>
1761 * <li>{@link #TIMED_WAITING}<br>
1762 * A thread that is waiting for another thread to perform an action
1763 * for up to a specified waiting time is in this state.
1764 * </li>
1765 * <li>{@link #TERMINATED}<br>
1766 * A thread that has exited is in this state.
1767 * </li>
1768 * </ul>
1769 *
1770 * <p>
1771 * A thread can be in only one state at a given point in time.
1772 * These states are virtual machine states which do not reflect
1773 * any operating system thread states.
1774 *
1775 * @since 1.5
1776 * @see #getState
1777 */
1778 public enum State {
1779 /**
1780 * Thread state for a thread which has not yet started.
1781 */
1782 NEW,
1783
1784 /**
1785 * Thread state for a runnable thread. A thread in the runnable
1786 * state is executing in the Java virtual machine but it may
1787 * be waiting for other resources from the operating system
1788 * such as processor.
1789 */
1790 RUNNABLE,
1791
1792 /**
1793 * Thread state for a thread blocked waiting for a monitor lock.
1794 * A thread in the blocked state is waiting for a monitor lock
1795 * to enter a synchronized block/method or
1796 * reenter a synchronized block/method after calling
1797 * {@link Object#wait() Object.wait}.
1798 */
1799 BLOCKED,
1800
1801 /**
1802 * Thread state for a waiting thread.
1803 * A thread is in the waiting state due to calling one of the
1804 * following methods:
1805 * <ul>
1806 * <li>{@link Object#wait() Object.wait} with no timeout</li>
1807 * <li>{@link #join() Thread.join} with no timeout</li>
1808 * <li>{@link LockSupport#park() LockSupport.park}</li>
1809 * </ul>
1810 *
1811 * <p>A thread in the waiting state is waiting for another thread to
1812 * perform a particular action.
1813 *
1814 * For example, a thread that has called {@code Object.wait()}
1815 * on an object is waiting for another thread to call
1816 * {@code Object.notify()} or {@code Object.notifyAll()} on
1817 * that object. A thread that has called {@code Thread.join()}
1818 * is waiting for a specified thread to terminate.
1819 */
1820 WAITING,
1821
1822 /**
1823 * Thread state for a waiting thread with a specified waiting time.
1824 * A thread is in the timed waiting state due to calling one of
1825 * the following methods with a specified positive waiting time:
1826 * <ul>
1827 * <li>{@link #sleep Thread.sleep}</li>
1828 * <li>{@link Object#wait(long) Object.wait} with timeout</li>
1829 * <li>{@link #join(long) Thread.join} with timeout</li>
1830 * <li>{@link LockSupport#parkNanos LockSupport.parkNanos}</li>
1831 * <li>{@link LockSupport#parkUntil LockSupport.parkUntil}</li>
1832 * </ul>
1833 */
1834 TIMED_WAITING,
1835
1836 /**
1837 * Thread state for a terminated thread.
1838 * The thread has completed execution.
1839 */
1840 TERMINATED;
1841 }
1842
1843 /**
1844 * Returns the state of this thread.
1845 * This method is designed for use in monitoring of the system state,
1846 * not for synchronization control.
1847 *
1848 * @return this thread's state.
1849 * @since 1.5
1850 */
1851 public State getState() {
1852 // get current thread state
1853 return jdk.internal.misc.VM.toThreadState(threadStatus);
1854 }
1855
1856 // Added in JSR-166
1857
1858 /**
1859 * Interface for handlers invoked when a {@code Thread} abruptly
1860 * terminates due to an uncaught exception.
1861 * <p>When a thread is about to terminate due to an uncaught exception
1862 * the Java Virtual Machine will query the thread for its
1863 * {@code UncaughtExceptionHandler} using
1864 * {@link #getUncaughtExceptionHandler} and will invoke the handler's
1865 * {@code uncaughtException} method, passing the thread and the
1866 * exception as arguments.
1867 * If a thread has not had its {@code UncaughtExceptionHandler}
1868 * explicitly set, then its {@code ThreadGroup} object acts as its
1869 * {@code UncaughtExceptionHandler}. If the {@code ThreadGroup} object
1870 * has no
1871 * special requirements for dealing with the exception, it can forward
1872 * the invocation to the {@linkplain #getDefaultUncaughtExceptionHandler
1873 * default uncaught exception handler}.
1874 *
1875 * @see #setDefaultUncaughtExceptionHandler
1876 * @see #setUncaughtExceptionHandler
1877 * @see ThreadGroup#uncaughtException
1878 * @since 1.5
1879 */
1880 @FunctionalInterface
1881 public interface UncaughtExceptionHandler {
1882 /**
1883 * Method invoked when the given thread terminates due to the
1884 * given uncaught exception.
1885 * <p>Any exception thrown by this method will be ignored by the
1886 * Java Virtual Machine.
1887 * @param t the thread
1888 * @param e the exception
1889 */
1890 void uncaughtException(Thread t, Throwable e);
1891 }
1892
1893 // null unless explicitly set
1894 private volatile UncaughtExceptionHandler uncaughtExceptionHandler;
1895
1896 // null unless explicitly set
1897 private static volatile UncaughtExceptionHandler defaultUncaughtExceptionHandler;
1898
1899 /**
1900 * Set the default handler invoked when a thread abruptly terminates
1901 * due to an uncaught exception, and no other handler has been defined
1902 * for that thread.
1903 *
1904 * <p>Uncaught exception handling is controlled first by the thread, then
1905 * by the thread's {@link ThreadGroup} object and finally by the default
1906 * uncaught exception handler. If the thread does not have an explicit
1907 * uncaught exception handler set, and the thread's thread group
1908 * (including parent thread groups) does not specialize its
1909 * {@code uncaughtException} method, then the default handler's
1910 * {@code uncaughtException} method will be invoked.
1911 * <p>By setting the default uncaught exception handler, an application
1912 * can change the way in which uncaught exceptions are handled (such as
1913 * logging to a specific device, or file) for those threads that would
1914 * already accept whatever "default" behavior the system
1915 * provided.
1916 *
1917 * <p>Note that the default uncaught exception handler should not usually
1918 * defer to the thread's {@code ThreadGroup} object, as that could cause
1919 * infinite recursion.
1920 *
1921 * @param eh the object to use as the default uncaught exception handler.
1922 * If {@code null} then there is no default handler.
1923 *
1924 * @throws SecurityException if a security manager is present and it denies
1925 * {@link RuntimePermission}{@code ("setDefaultUncaughtExceptionHandler")}
1926 *
1927 * @see #setUncaughtExceptionHandler
1928 * @see #getUncaughtExceptionHandler
1929 * @see ThreadGroup#uncaughtException
1930 * @since 1.5
1931 */
1932 public static void setDefaultUncaughtExceptionHandler(UncaughtExceptionHandler eh) {
1933 SecurityManager sm = System.getSecurityManager();
1934 if (sm != null) {
1935 sm.checkPermission(
1936 new RuntimePermission("setDefaultUncaughtExceptionHandler")
1937 );
1938 }
1939
1940 defaultUncaughtExceptionHandler = eh;
1941 }
1942
1943 /**
1944 * Returns the default handler invoked when a thread abruptly terminates
1945 * due to an uncaught exception. If the returned value is {@code null},
1946 * there is no default.
1947 * @since 1.5
1948 * @see #setDefaultUncaughtExceptionHandler
1949 * @return the default uncaught exception handler for all threads
1950 */
1951 public static UncaughtExceptionHandler getDefaultUncaughtExceptionHandler(){
1952 return defaultUncaughtExceptionHandler;
1953 }
1954
1955 /**
1956 * Returns the handler invoked when this thread abruptly terminates
1957 * due to an uncaught exception. If this thread has not had an
1958 * uncaught exception handler explicitly set then this thread's
1959 * {@code ThreadGroup} object is returned, unless this thread
1960 * has terminated, in which case {@code null} is returned.
1961 * @since 1.5
1962 * @return the uncaught exception handler for this thread
1963 */
1964 public UncaughtExceptionHandler getUncaughtExceptionHandler() {
1965 return uncaughtExceptionHandler != null ?
1966 uncaughtExceptionHandler : group;
1967 }
1968
1969 /**
1970 * Set the handler invoked when this thread abruptly terminates
1971 * due to an uncaught exception.
1972 * <p>A thread can take full control of how it responds to uncaught
1973 * exceptions by having its uncaught exception handler explicitly set.
1974 * If no such handler is set then the thread's {@code ThreadGroup}
1975 * object acts as its handler.
1976 * @param eh the object to use as this thread's uncaught exception
1977 * handler. If {@code null} then this thread has no explicit handler.
1978 * @throws SecurityException if the current thread is not allowed to
1979 * modify this thread.
1980 * @see #setDefaultUncaughtExceptionHandler
1981 * @see ThreadGroup#uncaughtException
1982 * @since 1.5
1983 */
1984 public void setUncaughtExceptionHandler(UncaughtExceptionHandler eh) {
1985 checkAccess();
1986 uncaughtExceptionHandler = eh;
1987 }
1988
1989 /**
1990 * Dispatch an uncaught exception to the handler. This method is
1991 * intended to be called only by the JVM.
1992 */
1993 private void dispatchUncaughtException(Throwable e) {
1994 getUncaughtExceptionHandler().uncaughtException(this, e);
1995 }
1996
1997 /**
1998 * Removes from the specified map any keys that have been enqueued
1999 * on the specified reference queue.
2000 */
2001 static void processQueue(ReferenceQueue<Class<?>> queue,
2002 ConcurrentMap<? extends
2003 WeakReference<Class<?>>, ?> map)
2004 {
2005 Reference<? extends Class<?>> ref;
2006 while((ref = queue.poll()) != null) {
2007 map.remove(ref);
2008 }
2009 }
2010
2011 /**
2012 * Weak key for Class objects.
2013 **/
2014 static class WeakClassKey extends WeakReference<Class<?>> {
2015 /**
2016 * saved value of the referent's identity hash code, to maintain
2017 * a consistent hash code after the referent has been cleared
2018 */
2019 private final int hash;
2020
2021 /**
2022 * Create a new WeakClassKey to the given object, registered
2023 * with a queue.
2024 */
2025 WeakClassKey(Class<?> cl, ReferenceQueue<Class<?>> refQueue) {
2026 super(cl, refQueue);
2027 hash = System.identityHashCode(cl);
2028 }
2029
2030 /**
2031 * Returns the identity hash code of the original referent.
2032 */
2033 @Override
2034 public int hashCode() {
2035 return hash;
2036 }
2037
2038 /**
2039 * Returns true if the given object is this identical
2040 * WeakClassKey instance, or, if this object's referent has not
2041 * been cleared, if the given object is another WeakClassKey
2042 * instance with the identical non-null referent as this one.
2043 */
2044 @Override
2045 public boolean equals(Object obj) {
2046 if (obj == this)
2047 return true;
2048
2049 if (obj instanceof WeakClassKey) {
2050 Object referent = get();
2051 return (referent != null) &&
2052 (referent == ((WeakClassKey) obj).get());
2053 } else {
2054 return false;
2055 }
2056 }
2057 }
2058
2059
2060 // The following three initially uninitialized fields are exclusively
2061 // managed by class java.util.concurrent.ThreadLocalRandom. These
2062 // fields are used to build the high-performance PRNGs in the
2063 // concurrent code, and we can not risk accidental false sharing.
2064 // Hence, the fields are isolated with @Contended.
2065
2066 /** The current seed for a ThreadLocalRandom */
2067 @jdk.internal.vm.annotation.Contended("tlr")
2068 long threadLocalRandomSeed;
2069
2070 /** Probe hash value; nonzero if threadLocalRandomSeed initialized */
2071 @jdk.internal.vm.annotation.Contended("tlr")
2072 int threadLocalRandomProbe;
2073
2074 /** Secondary seed isolated from public ThreadLocalRandom sequence */
2075 @jdk.internal.vm.annotation.Contended("tlr")
2076 int threadLocalRandomSecondarySeed;
2077
2078 /* Some private helper methods */
2079 private native void setPriority0(int newPriority);
2080 private native void stop0(Object o);
2081 private native void suspend0();
2082 private native void resume0();
2083 private native void interrupt0();
2084 private static native void clearInterruptEvent();
2085 private native void setNativeName(String name);
2086 }