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.locks.LockSupport;
39
40 import jdk.internal.misc.TerminatingThreadLocal;
41 import sun.nio.ch.Interruptible;
42 import jdk.internal.reflect.CallerSensitive;
43 import jdk.internal.reflect.Reflection;
44 import sun.security.util.SecurityConstants;
45 import jdk.internal.HotSpotIntrinsicCandidate;
46
47 /**
48 * A <i>thread</i> is a thread of execution in a program. The Java
49 * Virtual Machine allows an application to have multiple threads of
50 * execution running concurrently.
51 * <p>
52 * Every thread has a priority. Threads with higher priority are
53 * executed in preference to threads with lower priority. Each thread
54 * may or may not also be marked as a daemon. When code running in
55 * some thread creates a new {@code Thread} object, the new
56 * thread has its priority initially set equal to the priority of the
57 * creating thread, and is a daemon thread if and only if the
58 * creating thread is a daemon.
59 * <p>
60 * When a Java Virtual Machine starts up, there is usually a single
61 * non-daemon thread (which typically calls the method named
62 * {@code main} of some designated class). The Java Virtual
63 * Machine continues to execute threads until either of the following
64 * occurs:
65 * <ul>
66 * <li>The {@code exit} method of class {@code Runtime} has been
67 * called and the security manager has permitted the exit operation
68 * to take place.
69 * <li>All threads that are not daemon threads have died, either by
70 * returning from the call to the {@code run} method or by
71 * throwing an exception that propagates beyond the {@code run}
72 * method.
73 * </ul>
74 * <p>
75 * There are two ways to create a new thread of execution. One is to
76 * declare a class to be a subclass of {@code Thread}. This
77 * subclass should override the {@code run} method of class
78 * {@code Thread}. An instance of the subclass can then be
79 * allocated and started. For example, a thread that computes primes
80 * larger than a stated value could be written as follows:
81 * <hr><blockquote><pre>
82 * class PrimeThread extends Thread {
83 * long minPrime;
84 * PrimeThread(long minPrime) {
85 * this.minPrime = minPrime;
86 * }
87 *
88 * public void run() {
89 * // compute primes larger than minPrime
90 * . . .
91 * }
92 * }
93 * </pre></blockquote><hr>
94 * <p>
95 * The following code would then create a thread and start it running:
96 * <blockquote><pre>
97 * PrimeThread p = new PrimeThread(143);
98 * p.start();
99 * </pre></blockquote>
100 * <p>
101 * The other way to create a thread is to declare a class that
102 * implements the {@code Runnable} interface. That class then
103 * implements the {@code run} method. An instance of the class can
104 * then be allocated, passed as an argument when creating
105 * {@code Thread}, and started. The same example in this other
106 * style looks like the following:
107 * <hr><blockquote><pre>
108 * class PrimeRun implements Runnable {
109 * long minPrime;
110 * PrimeRun(long minPrime) {
111 * this.minPrime = minPrime;
112 * }
113 *
114 * public void run() {
115 * // compute primes larger than minPrime
116 * . . .
117 * }
118 * }
119 * </pre></blockquote><hr>
120 * <p>
121 * The following code would then create a thread and start it running:
122 * <blockquote><pre>
123 * PrimeRun p = new PrimeRun(143);
124 * new Thread(p).start();
125 * </pre></blockquote>
126 * <p>
127 * Every thread has a name for identification purposes. More than
128 * one thread may have the same name. If a name is not specified when
129 * a thread is created, a new name is generated for it.
130 * <p>
131 * Unless otherwise noted, passing a {@code null} argument to a constructor
132 * or method in this class will cause a {@link NullPointerException} to be
133 * thrown.
134 *
135 * @author unascribed
136 * @see Runnable
137 * @see Runtime#exit(int)
138 * @see #run()
139 * @see #stop()
140 * @since 1.0
141 */
142 public
143 class Thread implements Runnable {
144 /* Make sure registerNatives is the first thing <clinit> does. */
145 private static native void registerNatives();
146 static {
147 registerNatives();
148 }
149
150 private volatile String name;
151 private int priority;
152
153 /* Whether or not the thread is a daemon thread. */
154 private boolean daemon = false;
155
156 /* Fields reserved for exclusive use by the JVM */
157 private boolean stillborn = false;
158 private long eetop;
159
160 /* What will be run. */
161 private Runnable target;
162
163 /* The group of this thread */
164 private ThreadGroup group;
165
166 /* The context ClassLoader for this thread */
167 private ClassLoader contextClassLoader;
168
169 /* The inherited AccessControlContext of this thread */
170 private AccessControlContext inheritedAccessControlContext;
171
172 /* For autonumbering anonymous threads. */
173 private static int threadInitNumber;
174 private static synchronized int nextThreadNum() {
175 return threadInitNumber++;
176 }
177
178 /* ThreadLocal values pertaining to this thread. This map is maintained
179 * by the ThreadLocal class. */
180 ThreadLocal.ThreadLocalMap threadLocals = null;
181
182 /*
183 * InheritableThreadLocal values pertaining to this thread. This map is
184 * maintained by the InheritableThreadLocal class.
185 */
186 ThreadLocal.ThreadLocalMap inheritableThreadLocals = null;
187
188 /*
189 * The requested stack size for this thread, or 0 if the creator did
190 * not specify a stack size. It is up to the VM to do whatever it
191 * likes with this number; some VMs will ignore it.
192 */
193 private final long stackSize;
194
195 /*
196 * JVM-private state that persists after native thread termination.
197 */
198 private long nativeParkEventPointer;
199
200 /*
201 * Thread ID
202 */
203 private final long tid;
204
205 /* For generating thread ID */
206 private static long threadSeqNumber;
207
208 private static synchronized long nextThreadID() {
209 return ++threadSeqNumber;
210 }
211
212 /*
213 * Java thread status for tools, default indicates thread 'not yet started'
214 */
215 private volatile int threadStatus;
216
217 /**
218 * The argument supplied to the current call to
219 * java.util.concurrent.locks.LockSupport.park.
220 * Set by (private) java.util.concurrent.locks.LockSupport.setBlocker
221 * Accessed using java.util.concurrent.locks.LockSupport.getBlocker
222 */
223 volatile Object parkBlocker;
224
225 /* The object in which this thread is blocked in an interruptible I/O
226 * operation, if any. The blocker's interrupt method should be invoked
227 * after setting this thread's interrupt status.
228 */
229 private volatile Interruptible blocker;
230 private final Object blockerLock = new Object();
231
232 /* Set the blocker field; invoked via jdk.internal.misc.SharedSecrets
233 * from java.nio code
234 */
235 static void blockedOn(Interruptible b) {
236 Thread me = Thread.currentThread();
237 synchronized (me.blockerLock) {
238 me.blocker = b;
239 }
240 }
241
242 /**
243 * The minimum priority that a thread can have.
244 */
245 public static final int MIN_PRIORITY = 1;
246
247 /**
248 * The default priority that is assigned to a thread.
249 */
250 public static final int NORM_PRIORITY = 5;
251
252 /**
253 * The maximum priority that a thread can have.
254 */
255 public static final int MAX_PRIORITY = 10;
256
257 /**
258 * Returns a reference to the currently executing thread object.
259 *
260 * @return the currently executing thread.
261 */
262 @HotSpotIntrinsicCandidate
263 public static native Thread currentThread();
264
265 /**
266 * A hint to the scheduler that the current thread is willing to yield
267 * its current use of a processor. The scheduler is free to ignore this
268 * hint.
269 *
270 * <p> Yield is a heuristic attempt to improve relative progression
271 * between threads that would otherwise over-utilise a CPU. Its use
272 * should be combined with detailed profiling and benchmarking to
273 * ensure that it actually has the desired effect.
274 *
275 * <p> It is rarely appropriate to use this method. It may be useful
276 * for debugging or testing purposes, where it may help to reproduce
277 * bugs due to race conditions. It may also be useful when designing
278 * concurrency control constructs such as the ones in the
279 * {@link java.util.concurrent.locks} package.
280 */
281 public static native void yield();
282
283 /**
284 * Causes the currently executing thread to sleep (temporarily cease
285 * execution) for the specified number of milliseconds, subject to
286 * the precision and accuracy of system timers and schedulers. The thread
287 * does not lose ownership of any monitors.
288 *
289 * @param millis
290 * the length of time to sleep in milliseconds
291 *
292 * @throws IllegalArgumentException
293 * if the value of {@code millis} is negative
294 *
295 * @throws InterruptedException
296 * if any thread has interrupted the current thread. The
297 * <i>interrupted status</i> of the current thread is
298 * cleared when this exception is thrown.
299 */
300 public static native void sleep(long millis) throws InterruptedException;
301
302 /**
303 * Causes the currently executing thread to sleep (temporarily cease
304 * execution) for the specified number of milliseconds plus the specified
305 * number of nanoseconds, subject to the precision and accuracy of system
306 * timers and schedulers. The thread does not lose ownership of any
307 * monitors.
308 *
309 * @param millis
310 * the length of time to sleep in milliseconds
311 *
312 * @param nanos
313 * {@code 0-999999} additional nanoseconds to sleep
314 *
315 * @throws IllegalArgumentException
316 * if the value of {@code millis} is negative, or the value of
317 * {@code nanos} is not in the range {@code 0-999999}
318 *
319 * @throws InterruptedException
320 * if any thread has interrupted the current thread. The
321 * <i>interrupted status</i> of the current thread is
322 * cleared when this exception is thrown.
323 */
324 public static void sleep(long millis, int nanos)
325 throws InterruptedException {
326 if (millis < 0) {
327 throw new IllegalArgumentException("timeout value is negative");
328 }
329
330 if (nanos < 0 || nanos > 999999) {
331 throw new IllegalArgumentException(
332 "nanosecond timeout value out of range");
333 }
334
335 if (nanos >= 500000 || (nanos != 0 && millis == 0)) {
336 millis++;
337 }
338
339 sleep(millis);
340 }
341
342 /**
343 * Indicates that the caller is momentarily unable to progress, until the
344 * occurrence of one or more actions on the part of other activities. By
345 * invoking this method within each iteration of a spin-wait loop construct,
346 * the calling thread indicates to the runtime that it is busy-waiting.
347 * The runtime may take action to improve the performance of invoking
348 * spin-wait loop constructions.
349 *
350 * @apiNote
351 * As an example consider a method in a class that spins in a loop until
352 * some flag is set outside of that method. A call to the {@code onSpinWait}
353 * method should be placed inside the spin loop.
354 * <pre>{@code
355 * class EventHandler {
356 * volatile boolean eventNotificationNotReceived;
357 * void waitForEventAndHandleIt() {
358 * while ( eventNotificationNotReceived ) {
359 * java.lang.Thread.onSpinWait();
360 * }
361 * readAndProcessEvent();
362 * }
363 *
364 * void readAndProcessEvent() {
365 * // Read event from some source and process it
366 * . . .
367 * }
368 * }
369 * }</pre>
370 * <p>
371 * The code above would remain correct even if the {@code onSpinWait}
372 * method was not called at all. However on some architectures the Java
373 * Virtual Machine may issue the processor instructions to address such
374 * code patterns in a more beneficial way.
375 *
376 * @since 9
377 */
378 @HotSpotIntrinsicCandidate
379 public static void onSpinWait() {}
380
381 /**
382 * Initializes a Thread.
383 *
384 * @param g the Thread group
385 * @param target the object whose run() method gets called
386 * @param name the name of the new Thread
387 * @param stackSize the desired stack size for the new thread, or
388 * zero to indicate that this parameter is to be ignored.
389 * @param acc the AccessControlContext to inherit, or
390 * AccessController.getContext() if null
391 * @param inheritThreadLocals if {@code true}, inherit initial values for
392 * inheritable thread-locals from the constructing thread
393 */
394 private Thread(ThreadGroup g, Runnable target, String name,
395 long stackSize, AccessControlContext acc,
396 boolean inheritThreadLocals) {
397 if (name == null) {
398 throw new NullPointerException("name cannot be null");
399 }
400
401 this.name = name;
402
403 Thread parent = currentThread();
404 SecurityManager security = System.getSecurityManager();
405 if (g == null) {
406 /* Determine if it's an applet or not */
407
408 /* If there is a security manager, ask the security manager
409 what to do. */
410 if (security != null) {
411 g = security.getThreadGroup();
412 }
413
414 /* If the security manager doesn't have a strong opinion
415 on the matter, use the parent thread group. */
416 if (g == null) {
417 g = parent.getThreadGroup();
418 }
419 }
420
421 /* checkAccess regardless of whether or not threadgroup is
422 explicitly passed in. */
423 g.checkAccess();
424
425 /*
426 * Do we have the required permissions?
427 */
428 if (security != null) {
429 if (isCCLOverridden(getClass())) {
430 security.checkPermission(
431 SecurityConstants.SUBCLASS_IMPLEMENTATION_PERMISSION);
432 }
433 }
434
435 g.addUnstarted();
436
437 this.group = g;
438 this.daemon = parent.isDaemon();
439 this.priority = parent.getPriority();
440 if (security == null || isCCLOverridden(parent.getClass()))
441 this.contextClassLoader = parent.getContextClassLoader();
442 else
443 this.contextClassLoader = parent.contextClassLoader;
444 this.inheritedAccessControlContext =
445 acc != null ? acc : AccessController.getContext();
446 this.target = target;
447 setPriority(priority);
448 if (inheritThreadLocals && parent.inheritableThreadLocals != null)
449 this.inheritableThreadLocals =
450 ThreadLocal.createInheritedMap(parent.inheritableThreadLocals);
451 /* Stash the specified stack size in case the VM cares */
452 this.stackSize = stackSize;
453
454 /* Set thread ID */
455 this.tid = nextThreadID();
456 }
457
458 /**
459 * Throws CloneNotSupportedException as a Thread can not be meaningfully
460 * cloned. Construct a new Thread instead.
461 *
462 * @throws CloneNotSupportedException
463 * always
464 */
465 @Override
466 protected Object clone() throws CloneNotSupportedException {
467 throw new CloneNotSupportedException();
468 }
469
470 /**
471 * Allocates a new {@code Thread} object. This constructor has the same
472 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
473 * {@code (null, null, gname)}, where {@code gname} is a newly generated
474 * name. Automatically generated names are of the form
475 * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
476 */
477 public Thread() {
478 this(null, null, "Thread-" + nextThreadNum(), 0);
479 }
480
481 /**
482 * Allocates a new {@code Thread} object. This constructor has the same
483 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
484 * {@code (null, target, gname)}, where {@code gname} is a newly generated
485 * name. Automatically generated names are of the form
486 * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
487 *
488 * @param target
489 * the object whose {@code run} method is invoked when this thread
490 * is started. If {@code null}, this classes {@code run} method does
491 * nothing.
492 */
493 public Thread(Runnable target) {
494 this(null, target, "Thread-" + nextThreadNum(), 0);
495 }
496
497 /**
498 * Creates a new Thread that inherits the given AccessControlContext
499 * but thread-local variables are not inherited.
500 * This is not a public constructor.
501 */
502 Thread(Runnable target, AccessControlContext acc) {
503 this(null, target, "Thread-" + nextThreadNum(), 0, acc, false);
504 }
505
506 /**
507 * Allocates a new {@code Thread} object. This constructor has the same
508 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
509 * {@code (group, target, gname)} ,where {@code gname} is a newly generated
510 * name. Automatically generated names are of the form
511 * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
512 *
513 * @param group
514 * the thread group. If {@code null} and there is a security
515 * manager, the group is determined by {@linkplain
516 * SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
517 * If there is not a security manager or {@code
518 * SecurityManager.getThreadGroup()} returns {@code null}, the group
519 * is set to the current thread's thread group.
520 *
521 * @param target
522 * the object whose {@code run} method is invoked when this thread
523 * is started. If {@code null}, this thread's run method is invoked.
524 *
525 * @throws SecurityException
526 * if the current thread cannot create a thread in the specified
527 * thread group
528 */
529 public Thread(ThreadGroup group, Runnable target) {
530 this(group, target, "Thread-" + nextThreadNum(), 0);
531 }
532
533 /**
534 * Allocates a new {@code Thread} object. This constructor has the same
535 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
536 * {@code (null, null, name)}.
537 *
538 * @param name
539 * the name of the new thread
540 */
541 public Thread(String name) {
542 this(null, null, name, 0);
543 }
544
545 /**
546 * Allocates a new {@code Thread} object. This constructor has the same
547 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
548 * {@code (group, null, name)}.
549 *
550 * @param group
551 * the thread group. If {@code null} and there is a security
552 * manager, the group is determined by {@linkplain
553 * SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
554 * If there is not a security manager or {@code
555 * SecurityManager.getThreadGroup()} returns {@code null}, the group
556 * is set to the current thread's thread group.
557 *
558 * @param name
559 * the name of the new thread
560 *
561 * @throws SecurityException
562 * if the current thread cannot create a thread in the specified
563 * thread group
564 */
565 public Thread(ThreadGroup group, String name) {
566 this(group, null, name, 0);
567 }
568
569 /**
570 * Allocates a new {@code Thread} object. This constructor has the same
571 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
572 * {@code (null, target, name)}.
573 *
574 * @param target
575 * the object whose {@code run} method is invoked when this thread
576 * is started. If {@code null}, this thread's run method is invoked.
577 *
578 * @param name
579 * the name of the new thread
580 */
581 public Thread(Runnable target, String name) {
582 this(null, target, name, 0);
583 }
584
585 /**
586 * Allocates a new {@code Thread} object so that it has {@code target}
587 * as its run object, has the specified {@code name} as its name,
588 * and belongs to the thread group referred to by {@code group}.
589 *
590 * <p>If there is a security manager, its
591 * {@link SecurityManager#checkAccess(ThreadGroup) checkAccess}
592 * method is invoked with the ThreadGroup as its argument.
593 *
594 * <p>In addition, its {@code checkPermission} method is invoked with
595 * the {@code RuntimePermission("enableContextClassLoaderOverride")}
596 * permission when invoked directly or indirectly by the constructor
597 * of a subclass which overrides the {@code getContextClassLoader}
598 * or {@code setContextClassLoader} methods.
599 *
600 * <p>The priority of the newly created thread is set equal to the
601 * priority of the thread creating it, that is, the currently running
602 * thread. The method {@linkplain #setPriority setPriority} may be
603 * used to change the priority to a new value.
604 *
605 * <p>The newly created thread is initially marked as being a daemon
606 * thread if and only if the thread creating it is currently marked
607 * as a daemon thread. The method {@linkplain #setDaemon setDaemon}
608 * may be used to change whether or not a thread is a daemon.
609 *
610 * @param group
611 * the thread group. If {@code null} and there is a security
612 * manager, the group is determined by {@linkplain
613 * SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
614 * If there is not a security manager or {@code
615 * SecurityManager.getThreadGroup()} returns {@code null}, the group
616 * is set to the current thread's thread group.
617 *
618 * @param target
619 * the object whose {@code run} method is invoked when this thread
620 * is started. If {@code null}, this thread's run method is invoked.
621 *
622 * @param name
623 * the name of the new thread
624 *
625 * @throws SecurityException
626 * if the current thread cannot create a thread in the specified
627 * thread group or cannot override the context class loader methods.
628 */
629 public Thread(ThreadGroup group, Runnable target, String name) {
630 this(group, target, name, 0);
631 }
632
633 /**
634 * Allocates a new {@code Thread} object so that it has {@code target}
635 * as its run object, has the specified {@code name} as its name,
636 * and belongs to the thread group referred to by {@code group}, and has
637 * the specified <i>stack size</i>.
638 *
639 * <p>This constructor is identical to {@link
640 * #Thread(ThreadGroup,Runnable,String)} with the exception of the fact
641 * that it allows the thread stack size to be specified. The stack size
642 * is the approximate number of bytes of address space that the virtual
643 * machine is to allocate for this thread's stack. <b>The effect of the
644 * {@code stackSize} parameter, if any, is highly platform dependent.</b>
645 *
646 * <p>On some platforms, specifying a higher value for the
647 * {@code stackSize} parameter may allow a thread to achieve greater
648 * recursion depth before throwing a {@link StackOverflowError}.
649 * Similarly, specifying a lower value may allow a greater number of
650 * threads to exist concurrently without throwing an {@link
651 * OutOfMemoryError} (or other internal error). The details of
652 * the relationship between the value of the {@code stackSize} parameter
653 * and the maximum recursion depth and concurrency level are
654 * platform-dependent. <b>On some platforms, the value of the
655 * {@code stackSize} parameter may have no effect whatsoever.</b>
656 *
657 * <p>The virtual machine is free to treat the {@code stackSize}
658 * parameter as a suggestion. If the specified value is unreasonably low
659 * for the platform, the virtual machine may instead use some
660 * platform-specific minimum value; if the specified value is unreasonably
661 * high, the virtual machine may instead use some platform-specific
662 * maximum. Likewise, the virtual machine is free to round the specified
663 * value up or down as it sees fit (or to ignore it completely).
664 *
665 * <p>Specifying a value of zero for the {@code stackSize} parameter will
666 * cause this constructor to behave exactly like the
667 * {@code Thread(ThreadGroup, Runnable, String)} constructor.
668 *
669 * <p><i>Due to the platform-dependent nature of the behavior of this
670 * constructor, extreme care should be exercised in its use.
671 * The thread stack size necessary to perform a given computation will
672 * likely vary from one JRE implementation to another. In light of this
673 * variation, careful tuning of the stack size parameter may be required,
674 * and the tuning may need to be repeated for each JRE implementation on
675 * which an application is to run.</i>
676 *
677 * <p>Implementation note: Java platform implementers are encouraged to
678 * document their implementation's behavior with respect to the
679 * {@code stackSize} parameter.
680 *
681 *
682 * @param group
683 * the thread group. If {@code null} and there is a security
684 * manager, the group is determined by {@linkplain
685 * SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
686 * If there is not a security manager or {@code
687 * SecurityManager.getThreadGroup()} returns {@code null}, the group
688 * is set to the current thread's thread group.
689 *
690 * @param target
691 * the object whose {@code run} method is invoked when this thread
692 * is started. If {@code null}, this thread's run method is invoked.
693 *
694 * @param name
695 * the name of the new thread
696 *
697 * @param stackSize
698 * the desired stack size for the new thread, or zero to indicate
699 * that this parameter is to be ignored.
700 *
701 * @throws SecurityException
702 * if the current thread cannot create a thread in the specified
703 * thread group
704 *
705 * @since 1.4
706 */
707 public Thread(ThreadGroup group, Runnable target, String name,
708 long stackSize) {
709 this(group, target, name, stackSize, null, true);
710 }
711
712 /**
713 * Allocates a new {@code Thread} object so that it has {@code target}
714 * as its run object, has the specified {@code name} as its name,
715 * belongs to the thread group referred to by {@code group}, has
716 * the specified {@code stackSize}, and inherits initial values for
717 * {@linkplain InheritableThreadLocal inheritable thread-local} variables
718 * if {@code inheritThreadLocals} is {@code true}.
719 *
720 * <p> This constructor is identical to {@link
721 * #Thread(ThreadGroup,Runnable,String,long)} with the added ability to
722 * suppress, or not, the inheriting of initial values for inheritable
723 * thread-local variables from the constructing thread. This allows for
724 * finer grain control over inheritable thread-locals. Care must be taken
725 * when passing a value of {@code false} for {@code inheritThreadLocals},
726 * as it may lead to unexpected behavior if the new thread executes code
727 * that expects a specific thread-local value to be inherited.
728 *
729 * <p> Specifying a value of {@code true} for the {@code inheritThreadLocals}
730 * parameter will cause this constructor to behave exactly like the
731 * {@code Thread(ThreadGroup, Runnable, String, long)} constructor.
732 *
733 * @param group
734 * the thread group. If {@code null} and there is a security
735 * manager, the group is determined by {@linkplain
736 * SecurityManager#getThreadGroup SecurityManager.getThreadGroup()}.
737 * If there is not a security manager or {@code
738 * SecurityManager.getThreadGroup()} returns {@code null}, the group
739 * is set to the current thread's thread group.
740 *
741 * @param target
742 * the object whose {@code run} method is invoked when this thread
743 * is started. If {@code null}, this thread's run method is invoked.
744 *
745 * @param name
746 * the name of the new thread
747 *
748 * @param stackSize
749 * the desired stack size for the new thread, or zero to indicate
750 * that this parameter is to be ignored
751 *
752 * @param inheritThreadLocals
753 * if {@code true}, inherit initial values for inheritable
754 * thread-locals from the constructing thread, otherwise no initial
755 * values are inherited
756 *
757 * @throws SecurityException
758 * if the current thread cannot create a thread in the specified
759 * thread group
760 *
761 * @since 9
762 */
763 public Thread(ThreadGroup group, Runnable target, String name,
764 long stackSize, boolean inheritThreadLocals) {
765 this(group, target, name, stackSize, null, inheritThreadLocals);
766 }
767
768 /**
769 * Causes this thread to begin execution; the Java Virtual Machine
770 * calls the {@code run} method of this thread.
771 * <p>
772 * The result is that two threads are running concurrently: the
773 * current thread (which returns from the call to the
774 * {@code start} method) and the other thread (which executes its
775 * {@code run} method).
776 * <p>
777 * It is never legal to start a thread more than once.
778 * In particular, a thread may not be restarted once it has completed
779 * execution.
780 *
781 * @throws IllegalThreadStateException if the thread was already started.
782 * @see #run()
783 * @see #stop()
784 */
785 public synchronized void start() {
786 /**
787 * This method is not invoked for the main method thread or "system"
788 * group threads created/set up by the VM. Any new functionality added
789 * to this method in the future may have to also be added to the VM.
790 *
791 * A zero status value corresponds to state "NEW".
792 */
793 if (threadStatus != 0)
794 throw new IllegalThreadStateException();
795
796 /* Notify the group that this thread is about to be started
797 * so that it can be added to the group's list of threads
798 * and the group's unstarted count can be decremented. */
799 group.add(this);
800
801 boolean started = false;
802 try {
803 start0();
804 started = true;
805 } finally {
806 try {
807 if (!started) {
808 group.threadStartFailed(this);
809 }
810 } catch (Throwable ignore) {
811 /* do nothing. If start0 threw a Throwable then
812 it will be passed up the call stack */
813 }
814 }
815 }
816
817 private native void start0();
818
819 /**
820 * If this thread was constructed using a separate
821 * {@code Runnable} run object, then that
822 * {@code Runnable} object's {@code run} method is called;
823 * otherwise, this method does nothing and returns.
824 * <p>
825 * Subclasses of {@code Thread} should override this method.
826 *
827 * @see #start()
828 * @see #stop()
829 * @see #Thread(ThreadGroup, Runnable, String)
830 */
831 @Override
832 public void run() {
833 if (target != null) {
834 target.run();
835 }
836 }
837
838 /**
839 * This method is called by the system to give a Thread
840 * a chance to clean up before it actually exits.
841 */
842 private void exit() {
843 if (threadLocals != null && TerminatingThreadLocal.REGISTRY.isPresent()) {
844 TerminatingThreadLocal.threadTerminated();
845 }
846 if (group != null) {
847 group.threadTerminated(this);
848 group = null;
849 }
850 /* Aggressively null out all reference fields: see bug 4006245 */
851 target = null;
852 /* Speed the release of some of these resources */
853 threadLocals = null;
854 inheritableThreadLocals = null;
855 inheritedAccessControlContext = null;
856 blocker = null;
857 uncaughtExceptionHandler = null;
858 }
859
860 /**
861 * Forces the thread to stop executing.
862 * <p>
863 * If there is a security manager installed, its {@code checkAccess}
864 * method is called with {@code this}
865 * as its argument. This may result in a
866 * {@code SecurityException} being raised (in the current thread).
867 * <p>
868 * If this thread is different from the current thread (that is, the current
869 * thread is trying to stop a thread other than itself), the
870 * security manager's {@code checkPermission} method (with a
871 * {@code RuntimePermission("stopThread")} argument) is called in
872 * addition.
873 * Again, this may result in throwing a
874 * {@code SecurityException} (in the current thread).
875 * <p>
876 * The thread represented by this thread is forced to stop whatever
877 * it is doing abnormally and to throw a newly created
878 * {@code ThreadDeath} object as an exception.
879 * <p>
880 * It is permitted to stop a thread that has not yet been started.
881 * If the thread is eventually started, it immediately terminates.
882 * <p>
883 * An application should not normally try to catch
884 * {@code ThreadDeath} unless it must do some extraordinary
885 * cleanup operation (note that the throwing of
886 * {@code ThreadDeath} causes {@code finally} clauses of
887 * {@code try} statements to be executed before the thread
888 * officially dies). If a {@code catch} clause catches a
889 * {@code ThreadDeath} object, it is important to rethrow the
890 * object so that the thread actually dies.
891 * <p>
892 * The top-level error handler that reacts to otherwise uncaught
893 * exceptions does not print out a message or otherwise notify the
894 * application if the uncaught exception is an instance of
895 * {@code ThreadDeath}.
896 *
897 * @throws SecurityException if the current thread cannot
898 * modify this thread.
899 * @see #interrupt()
900 * @see #checkAccess()
901 * @see #run()
902 * @see #start()
903 * @see ThreadDeath
904 * @see ThreadGroup#uncaughtException(Thread,Throwable)
905 * @see SecurityManager#checkAccess(Thread)
906 * @see SecurityManager#checkPermission
907 * @deprecated This method is inherently unsafe. Stopping a thread with
908 * Thread.stop causes it to unlock all of the monitors that it
909 * has locked (as a natural consequence of the unchecked
910 * {@code ThreadDeath} exception propagating up the stack). If
911 * any of the objects previously protected by these monitors were in
912 * an inconsistent state, the damaged objects become visible to
913 * other threads, potentially resulting in arbitrary behavior. Many
914 * uses of {@code stop} should be replaced by code that simply
915 * modifies some variable to indicate that the target thread should
916 * stop running. The target thread should check this variable
917 * regularly, and return from its run method in an orderly fashion
918 * if the variable indicates that it is to stop running. If the
919 * target thread waits for long periods (on a condition variable,
920 * for example), the {@code interrupt} method should be used to
921 * interrupt the wait.
922 * For more information, see
923 * <a href="{@docRoot}/java.base/java/lang/doc-files/threadPrimitiveDeprecation.html">Why
924 * are Thread.stop, Thread.suspend and Thread.resume Deprecated?</a>.
925 */
926 @Deprecated(since="1.2")
927 public final void stop() {
928 SecurityManager security = System.getSecurityManager();
929 if (security != null) {
930 checkAccess();
931 if (this != Thread.currentThread()) {
932 security.checkPermission(SecurityConstants.STOP_THREAD_PERMISSION);
933 }
934 }
935 // A zero status value corresponds to "NEW", it can't change to
936 // not-NEW because we hold the lock.
937 if (threadStatus != 0) {
938 resume(); // Wake up thread if it was suspended; no-op otherwise
939 }
940
941 // The VM can handle all thread states
942 stop0(new ThreadDeath());
943 }
944
945 /**
946 * Interrupts this thread.
947 *
948 * <p> Unless the current thread is interrupting itself, which is
949 * always permitted, the {@link #checkAccess() checkAccess} method
950 * of this thread is invoked, which may cause a {@link
951 * SecurityException} to be thrown.
952 *
953 * <p> If this thread is blocked in an invocation of the {@link
954 * Object#wait() wait()}, {@link Object#wait(long) wait(long)}, or {@link
955 * Object#wait(long, int) wait(long, int)} methods of the {@link Object}
956 * class, or of the {@link #join()}, {@link #join(long)}, {@link
957 * #join(long, int)}, {@link #sleep(long)}, or {@link #sleep(long, int)},
958 * methods of this class, then its interrupt status will be cleared and it
959 * will receive an {@link InterruptedException}.
960 *
961 * <p> If this thread is blocked in an I/O operation upon an {@link
962 * java.nio.channels.InterruptibleChannel InterruptibleChannel}
963 * then the channel will be closed, the thread's interrupt
964 * status will be set, and the thread will receive a {@link
965 * java.nio.channels.ClosedByInterruptException}.
966 *
967 * <p> If this thread is blocked in a {@link java.nio.channels.Selector}
968 * then the thread's interrupt status will be set and it will return
969 * immediately from the selection operation, possibly with a non-zero
970 * value, just as if the selector's {@link
971 * java.nio.channels.Selector#wakeup wakeup} method were invoked.
972 *
973 * <p> If none of the previous conditions hold then this thread's interrupt
974 * status will be set. </p>
975 *
976 * <p> Interrupting a thread that is not alive need not have any effect.
977 *
978 * @throws SecurityException
979 * if the current thread cannot modify this thread
980 *
981 * @revised 6.0
982 * @spec JSR-51
983 */
984 public void interrupt() {
985 if (this != Thread.currentThread()) {
986 checkAccess();
987
988 // thread may be blocked in an I/O operation
989 synchronized (blockerLock) {
990 Interruptible b = blocker;
991 if (b != null) {
992 interrupt0(); // set interrupt status
993 b.interrupt(this);
994 return;
995 }
996 }
997 }
998
999 // set interrupt status
1000 interrupt0();
1001 }
1002
1003 /**
1004 * Tests whether the current thread has been interrupted. The
1005 * <i>interrupted status</i> of the thread is cleared by this method. In
1006 * other words, if this method were to be called twice in succession, the
1007 * second call would return false (unless the current thread were
1008 * interrupted again, after the first call had cleared its interrupted
1009 * status and before the second call had examined it).
1010 *
1011 * <p>A thread interruption ignored because a thread was not alive
1012 * at the time of the interrupt will be reflected by this method
1013 * returning false.
1014 *
1015 * @return {@code true} if the current thread has been interrupted;
1016 * {@code false} otherwise.
1017 * @see #isInterrupted()
1018 * @revised 6.0
1019 */
1020 public static boolean interrupted() {
1021 return currentThread().isInterrupted(true);
1022 }
1023
1024 /**
1025 * Tests whether this thread has been interrupted. The <i>interrupted
1026 * status</i> of the thread is unaffected by this method.
1027 *
1028 * <p>A thread interruption ignored because a thread was not alive
1029 * at the time of the interrupt will be reflected by this method
1030 * returning false.
1031 *
1032 * @return {@code true} if this thread has been interrupted;
1033 * {@code false} otherwise.
1034 * @see #interrupted()
1035 * @revised 6.0
1036 */
1037 public boolean isInterrupted() {
1038 return isInterrupted(false);
1039 }
1040
1041 /**
1042 * Tests if some Thread has been interrupted. The interrupted state
1043 * is reset or not based on the value of ClearInterrupted that is
1044 * passed.
1045 */
1046 @HotSpotIntrinsicCandidate
1047 private native boolean isInterrupted(boolean ClearInterrupted);
1048
1049 /**
1050 * Tests if this thread is alive. A thread is alive if it has
1051 * been started and has not yet died.
1052 *
1053 * @return {@code true} if this thread is alive;
1054 * {@code false} otherwise.
1055 */
1056 public final native boolean isAlive();
1057
1058 /**
1059 * Suspends this thread.
1060 * <p>
1061 * First, the {@code checkAccess} method of this thread is called
1062 * with no arguments. This may result in throwing a
1063 * {@code SecurityException }(in the current thread).
1064 * <p>
1065 * If the thread is alive, it is suspended and makes no further
1066 * progress unless and until it is resumed.
1067 *
1068 * @throws SecurityException if the current thread cannot modify
1069 * this thread.
1070 * @see #checkAccess
1071 * @deprecated This method has been deprecated, as it is
1072 * inherently deadlock-prone. If the target thread holds a lock on the
1073 * monitor protecting a critical system resource when it is suspended, no
1074 * thread can access this resource until the target thread is resumed. If
1075 * the thread that would resume the target thread attempts to lock this
1076 * monitor prior to calling {@code resume}, deadlock results. Such
1077 * deadlocks typically manifest themselves as "frozen" processes.
1078 * For more information, see
1079 * <a href="{@docRoot}/java.base/java/lang/doc-files/threadPrimitiveDeprecation.html">Why
1080 * are Thread.stop, Thread.suspend and Thread.resume Deprecated?</a>.
1081 */
1082 @Deprecated(since="1.2")
1083 public final void suspend() {
1084 checkAccess();
1085 suspend0();
1086 }
1087
1088 /**
1089 * Resumes a suspended thread.
1090 * <p>
1091 * First, the {@code checkAccess} method of this thread is called
1092 * with no arguments. This may result in throwing a
1093 * {@code SecurityException} (in the current thread).
1094 * <p>
1095 * If the thread is alive but suspended, it is resumed and is
1096 * permitted to make progress in its execution.
1097 *
1098 * @throws SecurityException if the current thread cannot modify this
1099 * thread.
1100 * @see #checkAccess
1101 * @see #suspend()
1102 * @deprecated This method exists solely for use with {@link #suspend},
1103 * which has been deprecated because it is deadlock-prone.
1104 * For more information, see
1105 * <a href="{@docRoot}/java.base/java/lang/doc-files/threadPrimitiveDeprecation.html">Why
1106 * are Thread.stop, Thread.suspend and Thread.resume Deprecated?</a>.
1107 */
1108 @Deprecated(since="1.2")
1109 public final void resume() {
1110 checkAccess();
1111 resume0();
1112 }
1113
1114 /**
1115 * Changes the priority of this thread.
1116 * <p>
1117 * First the {@code checkAccess} method of this thread is called
1118 * with no arguments. This may result in throwing a {@code SecurityException}.
1119 * <p>
1120 * Otherwise, the priority of this thread is set to the smaller of
1121 * the specified {@code newPriority} and the maximum permitted
1122 * priority of the thread's thread group.
1123 *
1124 * @param newPriority priority to set this thread to
1125 * @throws IllegalArgumentException If the priority is not in the
1126 * range {@code MIN_PRIORITY} to
1127 * {@code MAX_PRIORITY}.
1128 * @throws SecurityException if the current thread cannot modify
1129 * this thread.
1130 * @see #getPriority
1131 * @see #checkAccess()
1132 * @see #getThreadGroup()
1133 * @see #MAX_PRIORITY
1134 * @see #MIN_PRIORITY
1135 * @see ThreadGroup#getMaxPriority()
1136 */
1137 public final void setPriority(int newPriority) {
1138 ThreadGroup g;
1139 checkAccess();
1140 if (newPriority > MAX_PRIORITY || newPriority < MIN_PRIORITY) {
1141 throw new IllegalArgumentException();
1142 }
1143 if((g = getThreadGroup()) != null) {
1144 if (newPriority > g.getMaxPriority()) {
1145 newPriority = g.getMaxPriority();
1146 }
1147 setPriority0(priority = newPriority);
1148 }
1149 }
1150
1151 /**
1152 * Returns this thread's priority.
1153 *
1154 * @return this thread's priority.
1155 * @see #setPriority
1156 */
1157 public final int getPriority() {
1158 return priority;
1159 }
1160
1161 /**
1162 * Changes the name of this thread to be equal to the argument {@code name}.
1163 * <p>
1164 * First the {@code checkAccess} method of this thread is called
1165 * with no arguments. This may result in throwing a
1166 * {@code SecurityException}.
1167 *
1168 * @param name the new name for this thread.
1169 * @throws SecurityException if the current thread cannot modify this
1170 * thread.
1171 * @see #getName
1172 * @see #checkAccess()
1173 */
1174 public final synchronized void setName(String name) {
1175 checkAccess();
1176 if (name == null) {
1177 throw new NullPointerException("name cannot be null");
1178 }
1179
1180 this.name = name;
1181 if (threadStatus != 0) {
1182 setNativeName(name);
1183 }
1184 }
1185
1186 /**
1187 * Returns this thread's name.
1188 *
1189 * @return this thread's name.
1190 * @see #setName(String)
1191 */
1192 public final String getName() {
1193 return name;
1194 }
1195
1196 /**
1197 * Returns the thread group to which this thread belongs.
1198 * This method returns null if this thread has died
1199 * (been stopped).
1200 *
1201 * @return this thread's thread group.
1202 */
1203 public final ThreadGroup getThreadGroup() {
1204 return group;
1205 }
1206
1207 /**
1208 * Returns an estimate of the number of active threads in the current
1209 * thread's {@linkplain java.lang.ThreadGroup thread group} and its
1210 * subgroups. Recursively iterates over all subgroups in the current
1211 * thread's thread group.
1212 *
1213 * <p> The value returned is only an estimate because the number of
1214 * threads may change dynamically while this method traverses internal
1215 * data structures, and might be affected by the presence of certain
1216 * system threads. This method is intended primarily for debugging
1217 * and monitoring purposes.
1218 *
1219 * @return an estimate of the number of active threads in the current
1220 * thread's thread group and in any other thread group that
1221 * has the current thread's thread group as an ancestor
1222 */
1223 public static int activeCount() {
1224 return currentThread().getThreadGroup().activeCount();
1225 }
1226
1227 /**
1228 * Copies into the specified array every active thread in the current
1229 * thread's thread group and its subgroups. This method simply
1230 * invokes the {@link java.lang.ThreadGroup#enumerate(Thread[])}
1231 * method of the current thread's thread group.
1232 *
1233 * <p> An application might use the {@linkplain #activeCount activeCount}
1234 * method to get an estimate of how big the array should be, however
1235 * <i>if the array is too short to hold all the threads, the extra threads
1236 * are silently ignored.</i> If it is critical to obtain every active
1237 * thread in the current thread's thread group and its subgroups, the
1238 * invoker should verify that the returned int value is strictly less
1239 * than the length of {@code tarray}.
1240 *
1241 * <p> Due to the inherent race condition in this method, it is recommended
1242 * that the method only be used for debugging and monitoring purposes.
1243 *
1244 * @param tarray
1245 * an array into which to put the list of threads
1246 *
1247 * @return the number of threads put into the array
1248 *
1249 * @throws SecurityException
1250 * if {@link java.lang.ThreadGroup#checkAccess} determines that
1251 * the current thread cannot access its thread group
1252 */
1253 public static int enumerate(Thread tarray[]) {
1254 return currentThread().getThreadGroup().enumerate(tarray);
1255 }
1256
1257 /**
1258 * Counts the number of stack frames in this thread. The thread must
1259 * be suspended.
1260 *
1261 * @return the number of stack frames in this thread.
1262 * @throws IllegalThreadStateException if this thread is not
1263 * suspended.
1264 * @deprecated The definition of this call depends on {@link #suspend},
1265 * which is deprecated. Further, the results of this call
1266 * were never well-defined.
1267 * This method is subject to removal in a future version of Java SE.
1268 * @see StackWalker
1269 */
1270 @Deprecated(since="1.2", forRemoval=true)
1271 public native int countStackFrames();
1272
1273 /**
1274 * Waits at most {@code millis} milliseconds for this thread to
1275 * die. A timeout of {@code 0} means to wait forever.
1276 *
1277 * <p> This implementation uses a loop of {@code this.wait} calls
1278 * conditioned on {@code this.isAlive}. As a thread terminates the
1279 * {@code this.notifyAll} method is invoked. It is recommended that
1280 * applications not use {@code wait}, {@code notify}, or
1281 * {@code notifyAll} on {@code Thread} instances.
1282 *
1283 * @param millis
1284 * the time to wait in milliseconds
1285 *
1286 * @throws IllegalArgumentException
1287 * if the value of {@code millis} is negative
1288 *
1289 * @throws InterruptedException
1290 * if any thread has interrupted the current thread. The
1291 * <i>interrupted status</i> of the current thread is
1292 * cleared when this exception is thrown.
1293 */
1294 public final synchronized void join(long millis)
1295 throws InterruptedException {
1296 long base = System.currentTimeMillis();
1297 long now = 0;
1298
1299 if (millis < 0) {
1300 throw new IllegalArgumentException("timeout value is negative");
1301 }
1302
1303 if (millis == 0) {
1304 while (isAlive()) {
1305 wait(0);
1306 }
1307 } else {
1308 while (isAlive()) {
1309 long delay = millis - now;
1310 if (delay <= 0) {
1311 break;
1312 }
1313 wait(delay);
1314 now = System.currentTimeMillis() - base;
1315 }
1316 }
1317 }
1318
1319 /**
1320 * Waits at most {@code millis} milliseconds plus
1321 * {@code nanos} nanoseconds for this thread to die.
1322 *
1323 * <p> This implementation uses a loop of {@code this.wait} calls
1324 * conditioned on {@code this.isAlive}. As a thread terminates the
1325 * {@code this.notifyAll} method is invoked. It is recommended that
1326 * applications not use {@code wait}, {@code notify}, or
1327 * {@code notifyAll} on {@code Thread} instances.
1328 *
1329 * @param millis
1330 * the time to wait in milliseconds
1331 *
1332 * @param nanos
1333 * {@code 0-999999} additional nanoseconds to wait
1334 *
1335 * @throws IllegalArgumentException
1336 * if the value of {@code millis} is negative, or the value
1337 * of {@code nanos} is not in the range {@code 0-999999}
1338 *
1339 * @throws InterruptedException
1340 * if any thread has interrupted the current thread. The
1341 * <i>interrupted status</i> of the current thread is
1342 * cleared when this exception is thrown.
1343 */
1344 public final synchronized void join(long millis, int nanos)
1345 throws InterruptedException {
1346
1347 if (millis < 0) {
1348 throw new IllegalArgumentException("timeout value is negative");
1349 }
1350
1351 if (nanos < 0 || nanos > 999999) {
1352 throw new IllegalArgumentException(
1353 "nanosecond timeout value out of range");
1354 }
1355
1356 if (nanos >= 500000 || (nanos != 0 && millis == 0)) {
1357 millis++;
1358 }
1359
1360 join(millis);
1361 }
1362
1363 /**
1364 * Waits for this thread to die.
1365 *
1366 * <p> An invocation of this method behaves in exactly the same
1367 * way as the invocation
1368 *
1369 * <blockquote>
1370 * {@linkplain #join(long) join}{@code (0)}
1371 * </blockquote>
1372 *
1373 * @throws InterruptedException
1374 * if any thread has interrupted the current thread. The
1375 * <i>interrupted status</i> of the current thread is
1376 * cleared when this exception is thrown.
1377 */
1378 public final void join() throws InterruptedException {
1379 join(0);
1380 }
1381
1382 /**
1383 * Prints a stack trace of the current thread to the standard error stream.
1384 * This method is used only for debugging.
1385 */
1386 public static void dumpStack() {
1387 new Exception("Stack trace").printStackTrace();
1388 }
1389
1390 /**
1391 * Marks this thread as either a {@linkplain #isDaemon daemon} thread
1392 * or a user thread. The Java Virtual Machine exits when the only
1393 * threads running are all daemon threads.
1394 *
1395 * <p> This method must be invoked before the thread is started.
1396 *
1397 * @param on
1398 * if {@code true}, marks this thread as a daemon thread
1399 *
1400 * @throws IllegalThreadStateException
1401 * if this thread is {@linkplain #isAlive alive}
1402 *
1403 * @throws SecurityException
1404 * if {@link #checkAccess} determines that the current
1405 * thread cannot modify this thread
1406 */
1407 public final void setDaemon(boolean on) {
1408 checkAccess();
1409 if (isAlive()) {
1410 throw new IllegalThreadStateException();
1411 }
1412 daemon = on;
1413 }
1414
1415 /**
1416 * Tests if this thread is a daemon thread.
1417 *
1418 * @return {@code true} if this thread is a daemon thread;
1419 * {@code false} otherwise.
1420 * @see #setDaemon(boolean)
1421 */
1422 public final boolean isDaemon() {
1423 return daemon;
1424 }
1425
1426 /**
1427 * Determines if the currently running thread has permission to
1428 * modify this thread.
1429 * <p>
1430 * If there is a security manager, its {@code checkAccess} method
1431 * is called with this thread as its argument. This may result in
1432 * throwing a {@code SecurityException}.
1433 *
1434 * @throws SecurityException if the current thread is not allowed to
1435 * access this thread.
1436 * @see SecurityManager#checkAccess(Thread)
1437 */
1438 public final void checkAccess() {
1439 SecurityManager security = System.getSecurityManager();
1440 if (security != null) {
1441 security.checkAccess(this);
1442 }
1443 }
1444
1445 /**
1446 * Returns a string representation of this thread, including the
1447 * thread's name, priority, and thread group.
1448 *
1449 * @return a string representation of this thread.
1450 */
1451 public String toString() {
1452 ThreadGroup group = getThreadGroup();
1453 if (group != null) {
1454 return "Thread[" + getName() + "," + getPriority() + "," +
1455 group.getName() + "]";
1456 } else {
1457 return "Thread[" + getName() + "," + getPriority() + "," +
1458 "" + "]";
1459 }
1460 }
1461
1462 /**
1463 * Returns the context {@code ClassLoader} for this thread. The context
1464 * {@code ClassLoader} is provided by the creator of the thread for use
1465 * by code running in this thread when loading classes and resources.
1466 * If not {@linkplain #setContextClassLoader set}, the default is the
1467 * {@code ClassLoader} context of the parent thread. The context
1468 * {@code ClassLoader} of the
1469 * primordial thread is typically set to the class loader used to load the
1470 * application.
1471 *
1472 *
1473 * @return the context {@code ClassLoader} for this thread, or {@code null}
1474 * indicating the system class loader (or, failing that, the
1475 * bootstrap class loader)
1476 *
1477 * @throws SecurityException
1478 * if a security manager is present, and the caller's class loader
1479 * is not {@code null} and is not the same as or an ancestor of the
1480 * context class loader, and the caller does not have the
1481 * {@link RuntimePermission}{@code ("getClassLoader")}
1482 *
1483 * @since 1.2
1484 */
1485 @CallerSensitive
1486 public ClassLoader getContextClassLoader() {
1487 if (contextClassLoader == null)
1488 return null;
1489 SecurityManager sm = System.getSecurityManager();
1490 if (sm != null) {
1491 ClassLoader.checkClassLoaderPermission(contextClassLoader,
1492 Reflection.getCallerClass());
1493 }
1494 return contextClassLoader;
1495 }
1496
1497 /**
1498 * Sets the context ClassLoader for this Thread. The context
1499 * ClassLoader can be set when a thread is created, and allows
1500 * the creator of the thread to provide the appropriate class loader,
1501 * through {@code getContextClassLoader}, to code running in the thread
1502 * when loading classes and resources.
1503 *
1504 * <p>If a security manager is present, its {@link
1505 * SecurityManager#checkPermission(java.security.Permission) checkPermission}
1506 * method is invoked with a {@link RuntimePermission RuntimePermission}{@code
1507 * ("setContextClassLoader")} permission to see if setting the context
1508 * ClassLoader is permitted.
1509 *
1510 * @param cl
1511 * the context ClassLoader for this Thread, or null indicating the
1512 * system class loader (or, failing that, the bootstrap class loader)
1513 *
1514 * @throws SecurityException
1515 * if the current thread cannot set the context ClassLoader
1516 *
1517 * @since 1.2
1518 */
1519 public void setContextClassLoader(ClassLoader cl) {
1520 SecurityManager sm = System.getSecurityManager();
1521 if (sm != null) {
1522 sm.checkPermission(new RuntimePermission("setContextClassLoader"));
1523 }
1524 contextClassLoader = cl;
1525 }
1526
1527 /**
1528 * Returns {@code true} if and only if the current thread holds the
1529 * monitor lock on the specified object.
1530 *
1531 * <p>This method is designed to allow a program to assert that
1532 * the current thread already holds a specified lock:
1533 * <pre>
1534 * assert Thread.holdsLock(obj);
1535 * </pre>
1536 *
1537 * @param obj the object on which to test lock ownership
1538 * @throws NullPointerException if obj is {@code null}
1539 * @return {@code true} if the current thread holds the monitor lock on
1540 * the specified object.
1541 * @since 1.4
1542 */
1543 public static native boolean holdsLock(Object obj);
1544
1545 private static final StackTraceElement[] EMPTY_STACK_TRACE
1546 = new StackTraceElement[0];
1547
1548 /**
1549 * Returns an array of stack trace elements representing the stack dump
1550 * of this thread. This method will return a zero-length array if
1551 * this thread has not started, has started but has not yet been
1552 * scheduled to run by the system, or has terminated.
1553 * If the returned array is of non-zero length then the first element of
1554 * the array represents the top of the stack, which is the most recent
1555 * method invocation in the sequence. The last element of the array
1556 * represents the bottom of the stack, which is the least recent method
1557 * invocation in the sequence.
1558 *
1559 * <p>If there is a security manager, and this thread is not
1560 * the current thread, then the security manager's
1561 * {@code checkPermission} method is called with a
1562 * {@code RuntimePermission("getStackTrace")} permission
1563 * to see if it's ok to get the stack trace.
1564 *
1565 * <p>Some virtual machines may, under some circumstances, omit one
1566 * or more stack frames from the stack trace. In the extreme case,
1567 * a virtual machine that has no stack trace information concerning
1568 * this thread is permitted to return a zero-length array from this
1569 * method.
1570 *
1571 * @return an array of {@code StackTraceElement},
1572 * each represents one stack frame.
1573 *
1574 * @throws SecurityException
1575 * if a security manager exists and its
1576 * {@code checkPermission} method doesn't allow
1577 * getting the stack trace of thread.
1578 * @see SecurityManager#checkPermission
1579 * @see RuntimePermission
1580 * @see Throwable#getStackTrace
1581 *
1582 * @since 1.5
1583 */
1584 public StackTraceElement[] getStackTrace() {
1585 if (this != Thread.currentThread()) {
1586 // check for getStackTrace permission
1587 SecurityManager security = System.getSecurityManager();
1588 if (security != null) {
1589 security.checkPermission(
1590 SecurityConstants.GET_STACK_TRACE_PERMISSION);
1591 }
1592 // optimization so we do not call into the vm for threads that
1593 // have not yet started or have terminated
1594 if (!isAlive()) {
1595 return EMPTY_STACK_TRACE;
1596 }
1597 StackTraceElement[][] stackTraceArray = dumpThreads(new Thread[] {this});
1598 StackTraceElement[] stackTrace = stackTraceArray[0];
1599 // a thread that was alive during the previous isAlive call may have
1600 // since terminated, therefore not having a stacktrace.
1601 if (stackTrace == null) {
1602 stackTrace = EMPTY_STACK_TRACE;
1603 }
1604 return stackTrace;
1605 } else {
1606 return (new Exception()).getStackTrace();
1607 }
1608 }
1609
1610 /**
1611 * Returns a map of stack traces for all live threads.
1612 * The map keys are threads and each map value is an array of
1613 * {@code StackTraceElement} that represents the stack dump
1614 * of the corresponding {@code Thread}.
1615 * The returned stack traces are in the format specified for
1616 * the {@link #getStackTrace getStackTrace} method.
1617 *
1618 * <p>The threads may be executing while this method is called.
1619 * The stack trace of each thread only represents a snapshot and
1620 * each stack trace may be obtained at different time. A zero-length
1621 * array will be returned in the map value if the virtual machine has
1622 * no stack trace information about a thread.
1623 *
1624 * <p>If there is a security manager, then the security manager's
1625 * {@code checkPermission} method is called with a
1626 * {@code RuntimePermission("getStackTrace")} permission as well as
1627 * {@code RuntimePermission("modifyThreadGroup")} permission
1628 * to see if it is ok to get the stack trace of all threads.
1629 *
1630 * @return a {@code Map} from {@code Thread} to an array of
1631 * {@code StackTraceElement} that represents the stack trace of
1632 * the corresponding thread.
1633 *
1634 * @throws SecurityException
1635 * if a security manager exists and its
1636 * {@code checkPermission} method doesn't allow
1637 * getting the stack trace of thread.
1638 * @see #getStackTrace
1639 * @see SecurityManager#checkPermission
1640 * @see RuntimePermission
1641 * @see Throwable#getStackTrace
1642 *
1643 * @since 1.5
1644 */
1645 public static Map<Thread, StackTraceElement[]> getAllStackTraces() {
1646 // check for getStackTrace permission
1647 SecurityManager security = System.getSecurityManager();
1648 if (security != null) {
1649 security.checkPermission(
1650 SecurityConstants.GET_STACK_TRACE_PERMISSION);
1651 security.checkPermission(
1652 SecurityConstants.MODIFY_THREADGROUP_PERMISSION);
1653 }
1654
1655 // Get a snapshot of the list of all threads
1656 Thread[] threads = getThreads();
1657 StackTraceElement[][] traces = dumpThreads(threads);
1658 Map<Thread, StackTraceElement[]> m = new HashMap<>(threads.length);
1659 for (int i = 0; i < threads.length; i++) {
1660 StackTraceElement[] stackTrace = traces[i];
1661 if (stackTrace != null) {
1662 m.put(threads[i], stackTrace);
1663 }
1664 // else terminated so we don't put it in the map
1665 }
1666 return m;
1667 }
1668
1669 /** cache of subclass security audit results */
1670 /* Replace with ConcurrentReferenceHashMap when/if it appears in a future
1671 * release */
1672 private static class Caches {
1673 /** cache of subclass security audit results */
1674 static final ConcurrentMap<WeakClassKey,Boolean> subclassAudits =
1675 new ConcurrentHashMap<>();
1676
1677 /** queue for WeakReferences to audited subclasses */
1678 static final ReferenceQueue<Class<?>> subclassAuditsQueue =
1679 new ReferenceQueue<>();
1680 }
1681
1682 /**
1683 * Verifies that this (possibly subclass) instance can be constructed
1684 * without violating security constraints: the subclass must not override
1685 * security-sensitive non-final methods, or else the
1686 * "enableContextClassLoaderOverride" RuntimePermission is checked.
1687 */
1688 private static boolean isCCLOverridden(Class<?> cl) {
1689 if (cl == Thread.class)
1690 return false;
1691
1692 processQueue(Caches.subclassAuditsQueue, Caches.subclassAudits);
1693 WeakClassKey key = new WeakClassKey(cl, Caches.subclassAuditsQueue);
1694 Boolean result = Caches.subclassAudits.get(key);
1695 if (result == null) {
1696 result = Boolean.valueOf(auditSubclass(cl));
1697 Caches.subclassAudits.putIfAbsent(key, result);
1698 }
1699
1700 return result.booleanValue();
1701 }
1702
1703 /**
1704 * Performs reflective checks on given subclass to verify that it doesn't
1705 * override security-sensitive non-final methods. Returns true if the
1706 * subclass overrides any of the methods, false otherwise.
1707 */
1708 private static boolean auditSubclass(final Class<?> subcl) {
1709 Boolean result = AccessController.doPrivileged(
1710 new PrivilegedAction<>() {
1711 public Boolean run() {
1712 for (Class<?> cl = subcl;
1713 cl != Thread.class;
1714 cl = cl.getSuperclass())
1715 {
1716 try {
1717 cl.getDeclaredMethod("getContextClassLoader", new Class<?>[0]);
1718 return Boolean.TRUE;
1719 } catch (NoSuchMethodException ex) {
1720 }
1721 try {
1722 Class<?>[] params = {ClassLoader.class};
1723 cl.getDeclaredMethod("setContextClassLoader", params);
1724 return Boolean.TRUE;
1725 } catch (NoSuchMethodException ex) {
1726 }
1727 }
1728 return Boolean.FALSE;
1729 }
1730 }
1731 );
1732 return result.booleanValue();
1733 }
1734
1735 private static native StackTraceElement[][] dumpThreads(Thread[] threads);
1736 private static native Thread[] getThreads();
1737
1738 /**
1739 * Returns the identifier of this Thread. The thread ID is a positive
1740 * {@code long} number generated when this thread was created.
1741 * The thread ID is unique and remains unchanged during its lifetime.
1742 * When a thread is terminated, this thread ID may be reused.
1743 *
1744 * @return this thread's ID.
1745 * @since 1.5
1746 */
1747 public long getId() {
1748 return tid;
1749 }
1750
1751 /**
1752 * A thread state. A thread can be in one of the following states:
1753 * <ul>
1754 * <li>{@link #NEW}<br>
1755 * A thread that has not yet started is in this state.
1756 * </li>
1757 * <li>{@link #RUNNABLE}<br>
1758 * A thread executing in the Java virtual machine is in this state.
1759 * </li>
1760 * <li>{@link #BLOCKED}<br>
1761 * A thread that is blocked waiting for a monitor lock
1762 * is in this state.
1763 * </li>
1764 * <li>{@link #WAITING}<br>
1765 * A thread that is waiting indefinitely for another thread to
1766 * perform a particular action is in this state.
1767 * </li>
1768 * <li>{@link #TIMED_WAITING}<br>
1769 * A thread that is waiting for another thread to perform an action
1770 * for up to a specified waiting time is in this state.
1771 * </li>
1772 * <li>{@link #TERMINATED}<br>
1773 * A thread that has exited is in this state.
1774 * </li>
1775 * </ul>
1776 *
1777 * <p>
1778 * A thread can be in only one state at a given point in time.
1779 * These states are virtual machine states which do not reflect
1780 * any operating system thread states.
1781 *
1782 * @since 1.5
1783 * @see #getState
1784 */
1785 public enum State {
1786 /**
1787 * Thread state for a thread which has not yet started.
1788 */
1789 NEW,
1790
1791 /**
1792 * Thread state for a runnable thread. A thread in the runnable
1793 * state is executing in the Java virtual machine but it may
1794 * be waiting for other resources from the operating system
1795 * such as processor.
1796 */
1797 RUNNABLE,
1798
1799 /**
1800 * Thread state for a thread blocked waiting for a monitor lock.
1801 * A thread in the blocked state is waiting for a monitor lock
1802 * to enter a synchronized block/method or
1803 * reenter a synchronized block/method after calling
1804 * {@link Object#wait() Object.wait}.
1805 */
1806 BLOCKED,
1807
1808 /**
1809 * Thread state for a waiting thread.
1810 * A thread is in the waiting state due to calling one of the
1811 * following methods:
1812 * <ul>
1813 * <li>{@link Object#wait() Object.wait} with no timeout</li>
1814 * <li>{@link #join() Thread.join} with no timeout</li>
1815 * <li>{@link LockSupport#park() LockSupport.park}</li>
1816 * </ul>
1817 *
1818 * <p>A thread in the waiting state is waiting for another thread to
1819 * perform a particular action.
1820 *
1821 * For example, a thread that has called {@code Object.wait()}
1822 * on an object is waiting for another thread to call
1823 * {@code Object.notify()} or {@code Object.notifyAll()} on
1824 * that object. A thread that has called {@code Thread.join()}
1825 * is waiting for a specified thread to terminate.
1826 */
1827 WAITING,
1828
1829 /**
1830 * Thread state for a waiting thread with a specified waiting time.
1831 * A thread is in the timed waiting state due to calling one of
1832 * the following methods with a specified positive waiting time:
1833 * <ul>
1834 * <li>{@link #sleep Thread.sleep}</li>
1835 * <li>{@link Object#wait(long) Object.wait} with timeout</li>
1836 * <li>{@link #join(long) Thread.join} with timeout</li>
1837 * <li>{@link LockSupport#parkNanos LockSupport.parkNanos}</li>
1838 * <li>{@link LockSupport#parkUntil LockSupport.parkUntil}</li>
1839 * </ul>
1840 */
1841 TIMED_WAITING,
1842
1843 /**
1844 * Thread state for a terminated thread.
1845 * The thread has completed execution.
1846 */
1847 TERMINATED;
1848 }
1849
1850 /**
1851 * Returns the state of this thread.
1852 * This method is designed for use in monitoring of the system state,
1853 * not for synchronization control.
1854 *
1855 * @return this thread's state.
1856 * @since 1.5
1857 */
1858 public State getState() {
1859 // get current thread state
1860 return jdk.internal.misc.VM.toThreadState(threadStatus);
1861 }
1862
1863 // Added in JSR-166
1864
1865 /**
1866 * Interface for handlers invoked when a {@code Thread} abruptly
1867 * terminates due to an uncaught exception.
1868 * <p>When a thread is about to terminate due to an uncaught exception
1869 * the Java Virtual Machine will query the thread for its
1870 * {@code UncaughtExceptionHandler} using
1871 * {@link #getUncaughtExceptionHandler} and will invoke the handler's
1872 * {@code uncaughtException} method, passing the thread and the
1873 * exception as arguments.
1874 * If a thread has not had its {@code UncaughtExceptionHandler}
1875 * explicitly set, then its {@code ThreadGroup} object acts as its
1876 * {@code UncaughtExceptionHandler}. If the {@code ThreadGroup} object
1877 * has no
1878 * special requirements for dealing with the exception, it can forward
1879 * the invocation to the {@linkplain #getDefaultUncaughtExceptionHandler
1880 * default uncaught exception handler}.
1881 *
1882 * @see #setDefaultUncaughtExceptionHandler
1883 * @see #setUncaughtExceptionHandler
1884 * @see ThreadGroup#uncaughtException
1885 * @since 1.5
1886 */
1887 @FunctionalInterface
1888 public interface UncaughtExceptionHandler {
1889 /**
1890 * Method invoked when the given thread terminates due to the
1891 * given uncaught exception.
1892 * <p>Any exception thrown by this method will be ignored by the
1893 * Java Virtual Machine.
1894 * @param t the thread
1895 * @param e the exception
1896 */
1897 void uncaughtException(Thread t, Throwable e);
1898 }
1899
1900 // null unless explicitly set
1901 private volatile UncaughtExceptionHandler uncaughtExceptionHandler;
1902
1903 // null unless explicitly set
1904 private static volatile UncaughtExceptionHandler defaultUncaughtExceptionHandler;
1905
1906 /**
1907 * Set the default handler invoked when a thread abruptly terminates
1908 * due to an uncaught exception, and no other handler has been defined
1909 * for that thread.
1910 *
1911 * <p>Uncaught exception handling is controlled first by the thread, then
1912 * by the thread's {@link ThreadGroup} object and finally by the default
1913 * uncaught exception handler. If the thread does not have an explicit
1914 * uncaught exception handler set, and the thread's thread group
1915 * (including parent thread groups) does not specialize its
1916 * {@code uncaughtException} method, then the default handler's
1917 * {@code uncaughtException} method will be invoked.
1918 * <p>By setting the default uncaught exception handler, an application
1919 * can change the way in which uncaught exceptions are handled (such as
1920 * logging to a specific device, or file) for those threads that would
1921 * already accept whatever "default" behavior the system
1922 * provided.
1923 *
1924 * <p>Note that the default uncaught exception handler should not usually
1925 * defer to the thread's {@code ThreadGroup} object, as that could cause
1926 * infinite recursion.
1927 *
1928 * @param eh the object to use as the default uncaught exception handler.
1929 * If {@code null} then there is no default handler.
1930 *
1931 * @throws SecurityException if a security manager is present and it denies
1932 * {@link RuntimePermission}{@code ("setDefaultUncaughtExceptionHandler")}
1933 *
1934 * @see #setUncaughtExceptionHandler
1935 * @see #getUncaughtExceptionHandler
1936 * @see ThreadGroup#uncaughtException
1937 * @since 1.5
1938 */
1939 public static void setDefaultUncaughtExceptionHandler(UncaughtExceptionHandler eh) {
1940 SecurityManager sm = System.getSecurityManager();
1941 if (sm != null) {
1942 sm.checkPermission(
1943 new RuntimePermission("setDefaultUncaughtExceptionHandler")
1944 );
1945 }
1946
1947 defaultUncaughtExceptionHandler = eh;
1948 }
1949
1950 /**
1951 * Returns the default handler invoked when a thread abruptly terminates
1952 * due to an uncaught exception. If the returned value is {@code null},
1953 * there is no default.
1954 * @since 1.5
1955 * @see #setDefaultUncaughtExceptionHandler
1956 * @return the default uncaught exception handler for all threads
1957 */
1958 public static UncaughtExceptionHandler getDefaultUncaughtExceptionHandler(){
1959 return defaultUncaughtExceptionHandler;
1960 }
1961
1962 /**
1963 * Returns the handler invoked when this thread abruptly terminates
1964 * due to an uncaught exception. If this thread has not had an
1965 * uncaught exception handler explicitly set then this thread's
1966 * {@code ThreadGroup} object is returned, unless this thread
1967 * has terminated, in which case {@code null} is returned.
1968 * @since 1.5
1969 * @return the uncaught exception handler for this thread
1970 */
1971 public UncaughtExceptionHandler getUncaughtExceptionHandler() {
1972 return uncaughtExceptionHandler != null ?
1973 uncaughtExceptionHandler : group;
1974 }
1975
1976 /**
1977 * Set the handler invoked when this thread abruptly terminates
1978 * due to an uncaught exception.
1979 * <p>A thread can take full control of how it responds to uncaught
1980 * exceptions by having its uncaught exception handler explicitly set.
1981 * If no such handler is set then the thread's {@code ThreadGroup}
1982 * object acts as its handler.
1983 * @param eh the object to use as this thread's uncaught exception
1984 * handler. If {@code null} then this thread has no explicit handler.
1985 * @throws SecurityException if the current thread is not allowed to
1986 * modify this thread.
1987 * @see #setDefaultUncaughtExceptionHandler
1988 * @see ThreadGroup#uncaughtException
1989 * @since 1.5
1990 */
1991 public void setUncaughtExceptionHandler(UncaughtExceptionHandler eh) {
1992 checkAccess();
1993 uncaughtExceptionHandler = eh;
1994 }
1995
1996 /**
1997 * Dispatch an uncaught exception to the handler. This method is
1998 * intended to be called only by the JVM.
1999 */
2000 private void dispatchUncaughtException(Throwable e) {
2001 getUncaughtExceptionHandler().uncaughtException(this, e);
2002 }
2003
2004 /**
2005 * Removes from the specified map any keys that have been enqueued
2006 * on the specified reference queue.
2007 */
2008 static void processQueue(ReferenceQueue<Class<?>> queue,
2009 ConcurrentMap<? extends
2010 WeakReference<Class<?>>, ?> map)
2011 {
2012 Reference<? extends Class<?>> ref;
2013 while((ref = queue.poll()) != null) {
2014 map.remove(ref);
2015 }
2016 }
2017
2018 /**
2019 * Weak key for Class objects.
2020 **/
2021 static class WeakClassKey extends WeakReference<Class<?>> {
2022 /**
2023 * saved value of the referent's identity hash code, to maintain
2024 * a consistent hash code after the referent has been cleared
2025 */
2026 private final int hash;
2027
2028 /**
2029 * Create a new WeakClassKey to the given object, registered
2030 * with a queue.
2031 */
2032 WeakClassKey(Class<?> cl, ReferenceQueue<Class<?>> refQueue) {
2033 super(cl, refQueue);
2034 hash = System.identityHashCode(cl);
2035 }
2036
2037 /**
2038 * Returns the identity hash code of the original referent.
2039 */
2040 @Override
2041 public int hashCode() {
2042 return hash;
2043 }
2044
2045 /**
2046 * Returns true if the given object is this identical
2047 * WeakClassKey instance, or, if this object's referent has not
2048 * been cleared, if the given object is another WeakClassKey
2049 * instance with the identical non-null referent as this one.
2050 */
2051 @Override
2052 public boolean equals(Object obj) {
2053 if (obj == this)
2054 return true;
2055
2056 if (obj instanceof WeakClassKey) {
2057 Object referent = get();
2058 return (referent != null) &&
2059 (referent == ((WeakClassKey) obj).get());
2060 } else {
2061 return false;
2062 }
2063 }
2064 }
2065
2066
2067 // The following three initially uninitialized fields are exclusively
2068 // managed by class java.util.concurrent.ThreadLocalRandom. These
2069 // fields are used to build the high-performance PRNGs in the
2070 // concurrent code, and we can not risk accidental false sharing.
2071 // Hence, the fields are isolated with @Contended.
2072
2073 /** The current seed for a ThreadLocalRandom */
2074 @jdk.internal.vm.annotation.Contended("tlr")
2075 long threadLocalRandomSeed;
2076
2077 /** Probe hash value; nonzero if threadLocalRandomSeed initialized */
2078 @jdk.internal.vm.annotation.Contended("tlr")
2079 int threadLocalRandomProbe;
2080
2081 /** Secondary seed isolated from public ThreadLocalRandom sequence */
2082 @jdk.internal.vm.annotation.Contended("tlr")
2083 int threadLocalRandomSecondarySeed;
2084
2085 /* Some private helper methods */
2086 private native void setPriority0(int newPriority);
2087 private native void stop0(Object o);
2088 private native void suspend0();
2089 private native void resume0();
2090 private native void interrupt0();
2091 private native void setNativeName(String name);
2092 }