1 /*
2 * Copyright (c) 1994, 2025, 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.reflect.Field;
30 import java.time.Duration;
31 import java.util.Map;
32 import java.util.HashMap;
33 import java.util.Objects;
34 import java.util.concurrent.Executor;
35 import java.util.concurrent.ThreadFactory;
36 import java.util.concurrent.StructureViolationException;
37 import java.util.concurrent.locks.LockSupport;
38 import jdk.internal.event.ThreadSleepEvent;
39 import jdk.internal.javac.Restricted;
40 import jdk.internal.misc.TerminatingThreadLocal;
41 import jdk.internal.misc.Unsafe;
42 import jdk.internal.misc.VM;
43 import jdk.internal.reflect.CallerSensitive;
44 import jdk.internal.reflect.Reflection;
45 import jdk.internal.vm.Continuation;
46 import jdk.internal.vm.ScopedValueContainer;
47 import jdk.internal.vm.StackableScope;
48 import jdk.internal.vm.ThreadContainer;
49 import jdk.internal.vm.annotation.ForceInline;
50 import jdk.internal.vm.annotation.Hidden;
51 import jdk.internal.vm.annotation.IntrinsicCandidate;
52 import jdk.internal.vm.annotation.Stable;
53 import sun.nio.ch.Interruptible;
54
55 import static java.util.concurrent.TimeUnit.MILLISECONDS;
56 import static java.util.concurrent.TimeUnit.NANOSECONDS;
57
58 /**
59 * A <i>thread</i> is a thread of execution in a program. The Java
60 * virtual machine allows an application to have multiple threads of
61 * execution running concurrently.
62 *
63 * <p> {@code Thread} defines constructors and a {@link Builder} to create threads.
64 * {@linkplain #start() Starting} a thread schedules it to execute its {@link #run() run}
65 * method. The newly started thread executes concurrently with the thread that caused
66 * it to start.
67 *
68 * <p> A thread <i>terminates</i> if either its {@code run} method completes normally,
69 * or if its {@code run} method completes abruptly and the appropriate {@linkplain
70 * Thread.UncaughtExceptionHandler uncaught exception handler} completes normally or
71 * abruptly. With no code left to run, the thread has completed execution. The
72 * {@link #join() join} method can be used to wait for a thread to terminate.
73 *
74 * <p> Threads have a unique {@linkplain #threadId() identifier} and a {@linkplain
75 * #getName() name}. The identifier is generated when a {@code Thread} is created
76 * and cannot be changed. The thread name can be specified when creating a thread
77 * or can be {@linkplain #setName(String) changed} at a later time.
78 *
79 * <p> Threads support {@link ThreadLocal} variables. These are variables that are
80 * local to a thread, meaning a thread can have a copy of a variable that is set to
81 * a value that is independent of the value set by other threads. {@code Thread} also
82 * supports {@link InheritableThreadLocal} variables that are thread local variables
83 * that are inherited at thread creation time from the parent {@code Thread}.
84 * {@code Thread} supports a special inheritable thread local for the thread
85 * {@linkplain #getContextClassLoader() context-class-loader}.
86 *
87 * <h2><a id="platform-threads">Platform threads</a></h2>
88 * <p> {@code Thread} supports the creation of <i>platform threads</i> that are
89 * typically mapped 1:1 to kernel threads scheduled by the operating system.
90 * Platform threads will usually have a large stack and other resources that are
91 * maintained by the operating system. Platforms threads are suitable for executing
92 * all types of tasks but may be a limited resource.
93 *
94 * <p> Platform threads get an automatically generated thread name by default.
95 *
96 * <p> Platform threads are designated <i>daemon</i> or <i>non-daemon</i> threads.
97 * When the Java virtual machine starts up, there is usually one non-daemon
98 * thread (the thread that typically calls the application's {@code main} method).
99 * The <a href="Runtime.html#shutdown">shutdown sequence</a> begins when all started
100 * non-daemon threads have terminated. Unstarted non-daemon threads do not prevent
101 * the shutdown sequence from beginning.
102 *
103 * <p> In addition to the daemon status, platform threads have a {@linkplain
104 * #getPriority() thread priority} and are members of a {@linkplain ThreadGroup
105 * thread group}.
106 *
107 * <h2><a id="virtual-threads">Virtual threads</a></h2>
108 * <p> {@code Thread} also supports the creation of <i>virtual threads</i>.
109 * Virtual threads are typically <i>user-mode threads</i> scheduled by the Java
110 * runtime rather than the operating system. Virtual threads will typically require
111 * few resources and a single Java virtual machine may support millions of virtual
112 * threads. Virtual threads are suitable for executing tasks that spend most of
113 * the time blocked, often waiting for I/O operations to complete. Virtual threads
114 * are not intended for long running CPU intensive operations.
115 *
116 * <p> Virtual threads typically employ a small set of platform threads used as
117 * <em>carrier threads</em>. Locking and I/O operations are examples of operations
118 * where a carrier thread may be re-scheduled from one virtual thread to another.
119 * Code executing in a virtual thread is not aware of the underlying carrier thread.
120 * The {@linkplain Thread#currentThread()} method, used to obtain a reference
121 * to the <i>current thread</i>, will always return the {@code Thread} object
122 * for the virtual thread.
123 *
124 * <p> Virtual threads do not have a thread name by default. The {@link #getName()
125 * getName} method returns the empty string if a thread name is not set.
126 *
127 * <p> Virtual threads are daemon threads and so do not prevent the
128 * <a href="Runtime.html#shutdown">shutdown sequence</a> from beginning.
129 * Virtual threads have a fixed {@linkplain #getPriority() thread priority}
130 * that cannot be changed.
131 *
132 * <h2>Creating and starting threads</h2>
133 *
134 * <p> {@code Thread} defines public constructors for creating platform threads and
135 * the {@link #start() start} method to schedule threads to execute. {@code Thread}
136 * may be extended for customization and other advanced reasons although most
137 * applications should have little need to do this.
138 *
139 * <p> {@code Thread} defines a {@link Builder} API for creating and starting both
140 * platform and virtual threads. The following are examples that use the builder:
141 * {@snippet :
142 * Runnable runnable = ...
143 *
144 * // Start a daemon thread to run a task
145 * Thread thread = Thread.ofPlatform().daemon().start(runnable);
146 *
147 * // Create an unstarted thread with name "duke", its start() method
148 * // must be invoked to schedule it to execute.
149 * Thread thread = Thread.ofPlatform().name("duke").unstarted(runnable);
150 *
151 * // A ThreadFactory that creates daemon threads named "worker-0", "worker-1", ...
152 * ThreadFactory factory = Thread.ofPlatform().daemon().name("worker-", 0).factory();
153 *
154 * // Start a virtual thread to run a task
155 * Thread thread = Thread.ofVirtual().start(runnable);
156 *
157 * // A ThreadFactory that creates virtual threads
158 * ThreadFactory factory = Thread.ofVirtual().factory();
159 * }
160 *
161 * <h2><a id="inheritance">Inheritance when creating threads</a></h2>
162 * A {@code Thread} created with one of the public constructors inherits the daemon
163 * status and thread priority from the parent thread at the time that the child {@code
164 * Thread} is created. The {@linkplain ThreadGroup thread group} is also inherited when
165 * not provided to the constructor. When using a {@code Thread.Builder} to create a
166 * platform thread, the daemon status, thread priority, and thread group are inherited
167 * when not set on the builder. As with the constructors, inheriting from the parent
168 * thread is done when the child {@code Thread} is created.
169 *
170 * <p> A {@code Thread} inherits its initial values of {@linkplain InheritableThreadLocal
171 * inheritable-thread-local} variables (including the context class loader) from
172 * the parent thread values at the time that the child {@code Thread} is created.
173 * The 5-param {@linkplain Thread#Thread(ThreadGroup, Runnable, String, long, boolean)
174 * constructor} can be used to create a thread that does not inherit its initial
175 * values from the constructing thread. When using a {@code Thread.Builder}, the
176 * {@link Builder#inheritInheritableThreadLocals(boolean) inheritInheritableThreadLocals}
177 * method can be used to select if the initial values are inherited.
178 *
179 * <p> Unless otherwise specified, passing a {@code null} argument to a constructor
180 * or method in this class will cause a {@link NullPointerException} to be thrown.
181 *
182 * @implNote
183 * In the JDK Reference Implementation, the following system properties may be used to
184 * configure the built-in default virtual thread scheduler:
185 * <table class="striped">
186 * <caption style="display:none">System properties</caption>
187 * <thead>
188 * <tr>
189 * <th scope="col">System property</th>
190 * <th scope="col">Description</th>
191 * </tr>
192 * </thead>
193 * <tbody>
194 * <tr>
195 * <th scope="row">
196 * {@systemProperty jdk.virtualThreadScheduler.parallelism}
197 * </th>
198 * <td> The default scheduler's target parallelism. It defaults to the number of
199 * available processors. </td>
200 * </tr>
201 * <tr>
202 * <th scope="row">
203 * {@systemProperty jdk.virtualThreadScheduler.maxPoolSize}
204 * </th>
205 * <td> The maximum number of platform threads available to the default scheduler.
206 * It defaults to 256. </td>
207 * </tr>
208 * </tbody>
209 * </table>
210 *
211 * @since 1.0
212 */
213 public class Thread implements Runnable {
214 /* Make sure registerNatives is the first thing <clinit> does. */
215 private static native void registerNatives();
216 static {
217 registerNatives();
218 }
219
220 /*
221 * Reserved for exclusive use by the JVM. Cannot be moved to the FieldHolder
222 * as it needs to be set by the VM for JNI attaching threads, before executing
223 * the constructor that will create the FieldHolder. The historically named
224 * `eetop` holds the address of the underlying VM JavaThread, and is set to
225 * non-zero when the thread is started, and reset to zero when the thread terminates.
226 * A non-zero value indicates this thread isAlive().
227 */
228 private volatile long eetop;
229
230 // thread id
231 private final long tid;
232
233 // thread name
234 private volatile String name;
235
236 // interrupt status (read/written by VM)
237 volatile boolean interrupted;
238
239 // context ClassLoader
240 private volatile ClassLoader contextClassLoader;
241
242 // Additional fields for platform threads.
243 // All fields, except task and terminatingThreadLocals, are accessed directly by the VM.
244 private static class FieldHolder {
245 final ThreadGroup group;
246 final Runnable task;
247 final long stackSize;
248 volatile int priority;
249 volatile boolean daemon;
250 volatile int threadStatus;
251
252 // Used by NativeThread for signalling, set lazily, read from any thread
253 @Stable long nativeThreadID;
254
255 // This map is maintained by the ThreadLocal class
256 ThreadLocal.ThreadLocalMap terminatingThreadLocals;
257
258 FieldHolder(ThreadGroup group,
259 Runnable task,
260 long stackSize,
261 int priority,
262 boolean daemon) {
263 this.group = group;
264 this.task = task;
265 this.stackSize = stackSize;
266 this.priority = priority;
267 if (daemon)
268 this.daemon = true;
269 }
270 }
271 private final FieldHolder holder;
272
273 ThreadLocal.ThreadLocalMap terminatingThreadLocals() {
274 return holder.terminatingThreadLocals;
275 }
276
277 void setTerminatingThreadLocals(ThreadLocal.ThreadLocalMap map) {
278 holder.terminatingThreadLocals = map;
279 }
280
281 long nativeThreadID() {
282 return holder.nativeThreadID;
283 }
284
285 void setNativeThreadID(long id) {
286 holder.nativeThreadID = id;
287 }
288
289 /*
290 * ThreadLocal values pertaining to this thread. This map is maintained
291 * by the ThreadLocal class.
292 */
293 private ThreadLocal.ThreadLocalMap threadLocals;
294
295 ThreadLocal.ThreadLocalMap threadLocals() {
296 return threadLocals;
297 }
298
299 void setThreadLocals(ThreadLocal.ThreadLocalMap map) {
300 threadLocals = map;
301 }
302
303 /*
304 * InheritableThreadLocal values pertaining to this thread. This map is
305 * maintained by the InheritableThreadLocal class.
306 */
307 private ThreadLocal.ThreadLocalMap inheritableThreadLocals;
308
309 ThreadLocal.ThreadLocalMap inheritableThreadLocals() {
310 return inheritableThreadLocals;
311 }
312
313 void setInheritableThreadLocals(ThreadLocal.ThreadLocalMap map) {
314 inheritableThreadLocals = map;
315 }
316
317 /*
318 * Scoped value bindings are maintained by the ScopedValue class.
319 */
320 private Object scopedValueBindings;
321
322 // Special value to indicate this is a newly-created Thread
323 // Note that his must match the declaration in ScopedValue.
324 private static final Object NEW_THREAD_BINDINGS = Thread.class;
325
326 static Object scopedValueBindings() {
327 return currentThread().scopedValueBindings;
328 }
329
330 static void setScopedValueBindings(Object bindings) {
331 currentThread().scopedValueBindings = bindings;
332 }
333
334 /**
335 * Search the stack for the most recent scoped-value bindings.
336 */
337 @IntrinsicCandidate
338 static native Object findScopedValueBindings();
339
340 /**
341 * Inherit the scoped-value bindings from the given container.
342 * Invoked when starting a thread.
343 */
344 void inheritScopedValueBindings(ThreadContainer container) {
345 ScopedValueContainer.BindingsSnapshot snapshot;
346 if (container.owner() != null
347 && (snapshot = container.scopedValueBindings()) != null) {
348
349 // bindings established for running/calling an operation
350 Object bindings = snapshot.scopedValueBindings();
351 if (currentThread().scopedValueBindings != bindings) {
352 throw new StructureViolationException("Scoped value bindings have changed");
353 }
354
355 this.scopedValueBindings = bindings;
356 }
357 }
358
359 /*
360 * Lock object for thread interrupt.
361 */
362 final Object interruptLock = new Object();
363
364 /**
365 * The argument supplied to the current call to
366 * java.util.concurrent.locks.LockSupport.park.
367 * Set by (private) java.util.concurrent.locks.LockSupport.setBlocker
368 * Accessed using java.util.concurrent.locks.LockSupport.getBlocker
369 */
370 private volatile Object parkBlocker;
371
372 /* The object in which this thread is blocked in an interruptible I/O
373 * operation, if any. The blocker's interrupt method should be invoked
374 * after setting this thread's interrupt status.
375 */
376 private Interruptible nioBlocker;
377
378 Interruptible nioBlocker() {
379 //assert Thread.holdsLock(interruptLock);
380 return nioBlocker;
381 }
382
383 /* Set the blocker field; invoked via jdk.internal.access.SharedSecrets
384 * from java.nio code
385 */
386 void blockedOn(Interruptible b) {
387 //assert Thread.currentThread() == this;
388 synchronized (interruptLock) {
389 nioBlocker = b;
390 }
391 }
392
393 /**
394 * The minimum priority that a thread can have.
395 */
396 public static final int MIN_PRIORITY = 1;
397
398 /**
399 * The default priority that is assigned to a thread.
400 */
401 public static final int NORM_PRIORITY = 5;
402
403 /**
404 * The maximum priority that a thread can have.
405 */
406 public static final int MAX_PRIORITY = 10;
407
408 /*
409 * Current inner-most continuation.
410 */
411 private Continuation cont;
412
413 /**
414 * Returns the current continuation.
415 */
416 Continuation getContinuation() {
417 return cont;
418 }
419
420 /**
421 * Sets the current continuation.
422 */
423 void setContinuation(Continuation cont) {
424 this.cont = cont;
425 }
426
427 /**
428 * Returns the Thread object for the current platform thread. If the
429 * current thread is a virtual thread then this method returns the carrier.
430 */
431 @IntrinsicCandidate
432 static native Thread currentCarrierThread();
433
434 /**
435 * Returns the Thread object for the current thread.
436 * @return the current thread
437 */
438 @IntrinsicCandidate
439 public static native Thread currentThread();
440
441 /**
442 * Sets the Thread object to be returned by Thread.currentThread().
443 */
444 @IntrinsicCandidate
445 native void setCurrentThread(Thread thread);
446
447 // ScopedValue support:
448
449 @IntrinsicCandidate
450 static native Object[] scopedValueCache();
451
452 @IntrinsicCandidate
453 static native void setScopedValueCache(Object[] cache);
454
455 @IntrinsicCandidate
456 static native void ensureMaterializedForStackWalk(Object o);
457
458 /**
459 * A hint to the scheduler that the current thread is willing to yield
460 * its current use of a processor. The scheduler is free to ignore this
461 * hint.
462 *
463 * <p> Yield is a heuristic attempt to improve relative progression
464 * between threads that would otherwise over-utilise a CPU. Its use
465 * should be combined with detailed profiling and benchmarking to
466 * ensure that it actually has the desired effect.
467 *
468 * <p> It is rarely appropriate to use this method. It may be useful
469 * for debugging or testing purposes, where it may help to reproduce
470 * bugs due to race conditions. It may also be useful when designing
471 * concurrency control constructs such as the ones in the
472 * {@link java.util.concurrent.locks} package.
473 */
474 public static void yield() {
475 if (currentThread() instanceof VirtualThread vthread) {
476 vthread.tryYield();
477 } else {
478 yield0();
479 }
480 }
481
482 private static native void yield0();
483
484 /**
485 * Called before sleeping to create a jdk.ThreadSleep event.
486 */
487 private static ThreadSleepEvent beforeSleep(long nanos) {
488 try {
489 ThreadSleepEvent event = new ThreadSleepEvent();
490 if (event.isEnabled()) {
491 event.time = nanos;
492 event.begin();
493 return event;
494 }
495 } catch (OutOfMemoryError e) {
496 // ignore
497 }
498 return null;
499 }
500
501
502 /**
503 * Called after sleeping to commit the jdk.ThreadSleep event.
504 */
505 private static void afterSleep(ThreadSleepEvent event) {
506 if (event != null) {
507 try {
508 event.commit();
509 } catch (OutOfMemoryError e) {
510 // ignore
511 }
512 }
513 }
514
515 /**
516 * Sleep for the specified number of nanoseconds, subject to the precision
517 * and accuracy of system timers and schedulers.
518 */
519 private static void sleepNanos(long nanos) throws InterruptedException {
520 ThreadSleepEvent event = beforeSleep(nanos);
521 try {
522 if (currentThread() instanceof VirtualThread vthread) {
523 vthread.sleepNanos(nanos);
524 } else {
525 sleepNanos0(nanos);
526 }
527 } finally {
528 afterSleep(event);
529 }
530 }
531
532 private static native void sleepNanos0(long nanos) throws InterruptedException;
533
534 /**
535 * Causes the currently executing thread to sleep (temporarily cease
536 * execution) for the specified number of milliseconds, subject to
537 * the precision and accuracy of system timers and schedulers. The thread
538 * does not lose ownership of any monitors.
539 *
540 * @param millis
541 * the length of time to sleep in milliseconds
542 *
543 * @throws IllegalArgumentException
544 * if the value of {@code millis} is negative
545 *
546 * @throws InterruptedException
547 * if any thread has interrupted the current thread. The
548 * <i>interrupted status</i> of the current thread is
549 * cleared when this exception is thrown.
550 */
551 public static void sleep(long millis) throws InterruptedException {
552 if (millis < 0) {
553 throw new IllegalArgumentException("timeout value is negative");
554 }
555 long nanos = MILLISECONDS.toNanos(millis);
556 sleepNanos(nanos);
557 }
558
559 /**
560 * Causes the currently executing thread to sleep (temporarily cease
561 * execution) for the specified number of milliseconds plus the specified
562 * number of nanoseconds, subject to the precision and accuracy of system
563 * timers and schedulers. The thread does not lose ownership of any
564 * monitors.
565 *
566 * @param millis
567 * the length of time to sleep in milliseconds
568 *
569 * @param nanos
570 * {@code 0-999999} additional nanoseconds to sleep
571 *
572 * @throws IllegalArgumentException
573 * if the value of {@code millis} is negative, or the value of
574 * {@code nanos} is not in the range {@code 0-999999}
575 *
576 * @throws InterruptedException
577 * if any thread has interrupted the current thread. The
578 * <i>interrupted status</i> of the current thread is
579 * cleared when this exception is thrown.
580 */
581 public static void sleep(long millis, int nanos) throws InterruptedException {
582 if (millis < 0) {
583 throw new IllegalArgumentException("timeout value is negative");
584 }
585
586 if (nanos < 0 || nanos > 999999) {
587 throw new IllegalArgumentException("nanosecond timeout value out of range");
588 }
589
590 // total sleep time, in nanoseconds
591 long totalNanos = MILLISECONDS.toNanos(millis);
592 totalNanos += Math.min(Long.MAX_VALUE - totalNanos, nanos);
593 sleepNanos(totalNanos);
594 }
595
596 /**
597 * Causes the currently executing thread to sleep (temporarily cease
598 * execution) for the specified duration, subject to the precision and
599 * accuracy of system timers and schedulers. This method is a no-op if
600 * the duration is {@linkplain Duration#isNegative() negative}.
601 *
602 * @param duration
603 * the duration to sleep
604 *
605 * @throws InterruptedException
606 * if the current thread is interrupted while sleeping. The
607 * <i>interrupted status</i> of the current thread is
608 * cleared when this exception is thrown.
609 *
610 * @since 19
611 */
612 public static void sleep(Duration duration) throws InterruptedException {
613 long nanos = NANOSECONDS.convert(duration); // MAX_VALUE if > 292 years
614 if (nanos < 0) {
615 return;
616 }
617 sleepNanos(nanos);
618 }
619
620 /**
621 * Indicates that the caller is momentarily unable to progress, until the
622 * occurrence of one or more actions on the part of other activities. By
623 * invoking this method within each iteration of a spin-wait loop construct,
624 * the calling thread indicates to the runtime that it is busy-waiting.
625 * The runtime may take action to improve the performance of invoking
626 * spin-wait loop constructions.
627 *
628 * @apiNote
629 * As an example consider a method in a class that spins in a loop until
630 * some flag is set outside of that method. A call to the {@code onSpinWait}
631 * method should be placed inside the spin loop.
632 * {@snippet :
633 * class EventHandler {
634 * volatile boolean eventNotificationNotReceived;
635 * void waitForEventAndHandleIt() {
636 * while ( eventNotificationNotReceived ) {
637 * Thread.onSpinWait();
638 * }
639 * readAndProcessEvent();
640 * }
641 *
642 * void readAndProcessEvent() {
643 * // Read event from some source and process it
644 * . . .
645 * }
646 * }
647 * }
648 * <p>
649 * The code above would remain correct even if the {@code onSpinWait}
650 * method was not called at all. However on some architectures the Java
651 * Virtual Machine may issue the processor instructions to address such
652 * code patterns in a more beneficial way.
653 *
654 * @since 9
655 */
656 @IntrinsicCandidate
657 public static void onSpinWait() {}
658
659 /**
660 * Characteristic value signifying that initial values for {@link
661 * InheritableThreadLocal inheritable-thread-locals} are not inherited from
662 * the constructing thread.
663 * See Thread initialization.
664 */
665 static final int NO_INHERIT_THREAD_LOCALS = 1 << 2;
666
667 /**
668 * Thread identifier assigned to the primordial thread.
669 */
670 static final long PRIMORDIAL_TID = 3;
671
672 /**
673 * Helper class to generate thread identifiers. The identifiers start at
674 * {@link Thread#PRIMORDIAL_TID} +1 as this class cannot be used during
675 * early startup to generate the identifier for the primordial thread. The
676 * counter is off-heap and shared with the VM to allow it to assign thread
677 * identifiers to non-Java threads.
678 * See Thread initialization.
679 */
680 private static class ThreadIdentifiers {
681 private static final Unsafe U;
682 private static final long NEXT_TID_OFFSET;
683 static {
684 U = Unsafe.getUnsafe();
685 NEXT_TID_OFFSET = Thread.getNextThreadIdOffset();
686 }
687 static long next() {
688 return U.getAndAddLong(null, NEXT_TID_OFFSET, 1);
689 }
690 }
691
692 /**
693 * Initializes a platform Thread.
694 *
695 * @param g the Thread group, can be null
696 * @param name the name of the new Thread
697 * @param characteristics thread characteristics
698 * @param task the object whose run() method gets called
699 * @param stackSize the desired stack size for the new thread, or
700 * zero to indicate that this parameter is to be ignored.
701 */
702 Thread(ThreadGroup g, String name, int characteristics, Runnable task, long stackSize) {
703 Thread parent = currentThread();
704 boolean attached = (parent == this); // primordial or JNI attached
705
706 if (attached) {
707 if (g == null) {
708 throw new InternalError("group cannot be null when attaching");
709 }
710 this.holder = new FieldHolder(g, task, stackSize, NORM_PRIORITY, false);
711 } else {
712 if (g == null) {
713 // default to current thread's group
714 g = parent.getThreadGroup();
715 }
716 int priority = Math.min(parent.getPriority(), g.getMaxPriority());
717 this.holder = new FieldHolder(g, task, stackSize, priority, parent.isDaemon());
718 }
719
720 if (attached && VM.initLevel() < 1) {
721 this.tid = PRIMORDIAL_TID; // primordial thread
722 } else {
723 this.tid = ThreadIdentifiers.next();
724 }
725
726 this.name = (name != null) ? name : genThreadName();
727
728 // thread locals
729 if (!attached) {
730 if ((characteristics & NO_INHERIT_THREAD_LOCALS) == 0) {
731 ThreadLocal.ThreadLocalMap parentMap = parent.inheritableThreadLocals;
732 if (parentMap != null && parentMap.size() > 0) {
733 this.inheritableThreadLocals = ThreadLocal.createInheritedMap(parentMap);
734 }
735 if (VM.isBooted()) {
736 this.contextClassLoader = parent.getContextClassLoader();
737 }
738 } else if (VM.isBooted()) {
739 // default CCL to the system class loader when not inheriting
740 this.contextClassLoader = ClassLoader.getSystemClassLoader();
741 }
742 }
743
744 // special value to indicate this is a newly-created Thread
745 // Note that his must match the declaration in ScopedValue.
746 this.scopedValueBindings = NEW_THREAD_BINDINGS;
747 }
748
749 /**
750 * Initializes a virtual Thread.
751 *
752 * @param name thread name, can be null
753 * @param characteristics thread characteristics
754 * @param bound true when bound to an OS thread
755 */
756 Thread(String name, int characteristics, boolean bound) {
757 this.tid = ThreadIdentifiers.next();
758 this.name = (name != null) ? name : "";
759
760 // thread locals
761 if ((characteristics & NO_INHERIT_THREAD_LOCALS) == 0) {
762 Thread parent = currentThread();
763 ThreadLocal.ThreadLocalMap parentMap = parent.inheritableThreadLocals;
764 if (parentMap != null && parentMap.size() > 0) {
765 this.inheritableThreadLocals = ThreadLocal.createInheritedMap(parentMap);
766 }
767 this.contextClassLoader = parent.getContextClassLoader();
768 } else {
769 // default CCL to the system class loader when not inheriting
770 this.contextClassLoader = ClassLoader.getSystemClassLoader();
771 }
772
773 // special value to indicate this is a newly-created Thread
774 this.scopedValueBindings = NEW_THREAD_BINDINGS;
775
776 // create a FieldHolder object, needed when bound to an OS thread
777 if (bound) {
778 ThreadGroup g = Constants.VTHREAD_GROUP;
779 int pri = NORM_PRIORITY;
780 this.holder = new FieldHolder(g, null, -1, pri, true);
781 } else {
782 this.holder = null;
783 }
784 }
785
786 /**
787 * Virtual thread scheduler.
788 *
789 * @apiNote The following example creates a virtual thread scheduler that uses a small
790 * set of platform threads.
791 * {@snippet lang=java :
792 * ExecutorService pool = Executors.newFixedThreadPool(4);
793 * VirtualThreadScheduler scheduler = (vthread, task) -> {
794 * pool.submit(() -> {
795 * Thread carrier = Thread.currentThread();
796 *
797 * // runs the virtual thread task
798 * task.run();
799 *
800 * assert Thread.currentThread() == carrier;
801 * });
802 * };
803 * }
804 *
805 * <p> Unless otherwise specified, passing a null argument to a method in
806 * this interface causes a {@code NullPointerException} to be thrown.
807 *
808 * @see Builder.OfVirtual#scheduler(VirtualThreadScheduler)
809 * @since 99
810 */
811 @FunctionalInterface
812 public interface VirtualThreadScheduler {
813 /**
814 * Continue execution of given virtual thread by executing the given task on
815 * a platform thread.
816 *
817 * @param vthread the virtual thread
818 * @param task the task to execute
819 */
820 void execute(Thread vthread, Runnable task);
821
822 /**
823 * {@return a virtual thread scheduler that delegates tasks to the given executor}
824 * @param executor the executor
825 */
826 static VirtualThreadScheduler adapt(Executor executor) {
827 Objects.requireNonNull(executor);
828 return (_, task) -> executor.execute(task);
829 }
830
831 /**
832 * {@return the virtual thread scheduler for the current virtual thread}
833 * @throws UnsupportedOperationException if the current thread is not a virtual
834 * thread or scheduling virtual threads to a user-provided scheduler is not
835 * supported by this VM
836 */
837 @CallerSensitive
838 @Restricted
839 static VirtualThreadScheduler current() {
840 Class<?> caller = Reflection.getCallerClass();
841 caller.getModule().ensureNativeAccess(VirtualThreadScheduler.class,
842 "current",
843 caller,
844 false);
845 if (Thread.currentThread() instanceof VirtualThread vthread) {
846 return vthread.scheduler(false);
847 } else {
848 throw new UnsupportedOperationException();
849 }
850 }
851 }
852
853 /**
854 * Returns a builder for creating a platform {@code Thread} or {@code ThreadFactory}
855 * that creates platform threads.
856 *
857 * @apiNote The following are examples using the builder:
858 * {@snippet :
859 * // Start a daemon thread to run a task
860 * Thread thread = Thread.ofPlatform().daemon().start(runnable);
861 *
862 * // Create an unstarted thread with name "duke", its start() method
863 * // must be invoked to schedule it to execute.
864 * Thread thread = Thread.ofPlatform().name("duke").unstarted(runnable);
865 *
866 * // A ThreadFactory that creates daemon threads named "worker-0", "worker-1", ...
867 * ThreadFactory factory = Thread.ofPlatform().daemon().name("worker-", 0).factory();
868 * }
869 *
870 * @return A builder for creating {@code Thread} or {@code ThreadFactory} objects.
871 * @since 21
872 */
873 public static Builder.OfPlatform ofPlatform() {
874 return new ThreadBuilders.PlatformThreadBuilder();
875 }
876
877 /**
878 * Returns a builder for creating a virtual {@code Thread} or {@code ThreadFactory}
879 * that creates virtual threads.
880 *
881 * @apiNote The following are examples using the builder:
882 * {@snippet :
883 * // Start a virtual thread to run a task.
884 * Thread thread = Thread.ofVirtual().start(runnable);
885 *
886 * // A ThreadFactory that creates virtual threads
887 * ThreadFactory factory = Thread.ofVirtual().factory();
888 * }
889 *
890 * @return A builder for creating {@code Thread} or {@code ThreadFactory} objects.
891 * @since 21
892 */
893 public static Builder.OfVirtual ofVirtual() {
894 return new ThreadBuilders.VirtualThreadBuilder();
895 }
896
897 /**
898 * A builder for {@link Thread} and {@link ThreadFactory} objects.
899 *
900 * <p> {@code Builder} defines methods to set {@code Thread} properties such
901 * as the thread {@link #name(String) name}. This includes properties that would
902 * otherwise be <a href="Thread.html#inheritance">inherited</a>. Once set, a
903 * {@code Thread} or {@code ThreadFactory} is created with the following methods:
904 *
905 * <ul>
906 * <li> The {@linkplain #unstarted(Runnable) unstarted} method creates a new
907 * <em>unstarted</em> {@code Thread} to run a task. The {@code Thread}'s
908 * {@link Thread#start() start} method must be invoked to schedule the
909 * thread to execute.
910 * <li> The {@linkplain #start(Runnable) start} method creates a new {@code
911 * Thread} to run a task and schedules the thread to execute.
912 * <li> The {@linkplain #factory() factory} method creates a {@code ThreadFactory}.
913 * </ul>
914 *
915 * <p> A {@code Thread.Builder} is not thread safe. The {@code ThreadFactory}
916 * returned by the builder's {@code factory()} method is thread safe.
917 *
918 * <p> Unless otherwise specified, passing a null argument to a method in
919 * this interface causes a {@code NullPointerException} to be thrown.
920 *
921 * @see Thread#ofPlatform()
922 * @see Thread#ofVirtual()
923 * @since 21
924 */
925 public sealed interface Builder
926 permits Builder.OfPlatform, Builder.OfVirtual {
927
928 /**
929 * Sets the thread name.
930 * @param name thread name
931 * @return this builder
932 */
933 Builder name(String name);
934
935 /**
936 * Sets the thread name to be the concatenation of a string prefix and
937 * the string representation of a counter value. The counter's initial
938 * value is {@code start}. It is incremented after a {@code Thread} is
939 * created with this builder so that the next thread is named with
940 * the new counter value. A {@code ThreadFactory} created with this
941 * builder is seeded with the current value of the counter. The {@code
942 * ThreadFactory} increments its copy of the counter after {@link
943 * ThreadFactory#newThread(Runnable) newThread} is used to create a
944 * {@code Thread}.
945 *
946 * @apiNote
947 * The following example creates a builder that is invoked twice to start
948 * two threads named "{@code worker-0}" and "{@code worker-1}".
949 * {@snippet :
950 * Thread.Builder builder = Thread.ofPlatform().name("worker-", 0);
951 * Thread t1 = builder.start(task1); // name "worker-0"
952 * Thread t2 = builder.start(task2); // name "worker-1"
953 * }
954 *
955 * @param prefix thread name prefix
956 * @param start the starting value of the counter
957 * @return this builder
958 * @throws IllegalArgumentException if start is negative
959 */
960 Builder name(String prefix, long start);
961
962 /**
963 * Sets whether the thread inherits the initial values of {@linkplain
964 * InheritableThreadLocal inheritable-thread-local} variables from the
965 * constructing thread. The default is to inherit.
966 *
967 * @param inherit {@code true} to inherit, {@code false} to not inherit
968 * @return this builder
969 */
970 Builder inheritInheritableThreadLocals(boolean inherit);
971
972 /**
973 * Sets the uncaught exception handler.
974 * @param ueh uncaught exception handler
975 * @return this builder
976 */
977 Builder uncaughtExceptionHandler(UncaughtExceptionHandler ueh);
978
979 /**
980 * Creates a new {@code Thread} from the current state of the builder to
981 * run the given task. The {@code Thread}'s {@link Thread#start() start}
982 * method must be invoked to schedule the thread to execute.
983 *
984 * @param task the object to run when the thread executes
985 * @return a new unstarted Thread
986 *
987 * @see <a href="Thread.html#inheritance">Inheritance when creating threads</a>
988 */
989 Thread unstarted(Runnable task);
990
991 /**
992 * Creates a new {@code Thread} from the current state of the builder and
993 * schedules it to execute.
994 *
995 * @param task the object to run when the thread executes
996 * @return a new started Thread
997 *
998 * @see <a href="Thread.html#inheritance">Inheritance when creating threads</a>
999 */
1000 Thread start(Runnable task);
1001
1002 /**
1003 * Returns a {@code ThreadFactory} to create threads from the current
1004 * state of the builder. The returned thread factory is safe for use by
1005 * multiple concurrent threads.
1006 *
1007 * @return a thread factory to create threads
1008 */
1009 ThreadFactory factory();
1010
1011 /**
1012 * A builder for creating a platform {@link Thread} or {@link ThreadFactory}
1013 * that creates platform threads.
1014 *
1015 * <p> Unless otherwise specified, passing a null argument to a method in
1016 * this interface causes a {@code NullPointerException} to be thrown.
1017 *
1018 * @see Thread#ofPlatform()
1019 * @since 21
1020 */
1021 sealed interface OfPlatform extends Builder
1022 permits ThreadBuilders.PlatformThreadBuilder {
1023
1024 @Override OfPlatform name(String name);
1025
1026 /**
1027 * @throws IllegalArgumentException {@inheritDoc}
1028 */
1029 @Override OfPlatform name(String prefix, long start);
1030
1031 @Override OfPlatform inheritInheritableThreadLocals(boolean inherit);
1032 @Override OfPlatform uncaughtExceptionHandler(UncaughtExceptionHandler ueh);
1033
1034 /**
1035 * Sets the thread group.
1036 * @param group the thread group
1037 * @return this builder
1038 */
1039 OfPlatform group(ThreadGroup group);
1040
1041 /**
1042 * Sets the daemon status.
1043 * @param on {@code true} to create daemon threads
1044 * @return this builder
1045 */
1046 OfPlatform daemon(boolean on);
1047
1048 /**
1049 * Sets the daemon status to {@code true}.
1050 * @implSpec The default implementation invokes {@linkplain #daemon(boolean)} with
1051 * a value of {@code true}.
1052 * @return this builder
1053 */
1054 default OfPlatform daemon() {
1055 return daemon(true);
1056 }
1057
1058 /**
1059 * Sets the thread priority.
1060 * @param priority priority
1061 * @return this builder
1062 * @throws IllegalArgumentException if the priority is less than
1063 * {@link Thread#MIN_PRIORITY} or greater than {@link Thread#MAX_PRIORITY}
1064 */
1065 OfPlatform priority(int priority);
1066
1067 /**
1068 * Sets the desired stack size.
1069 *
1070 * <p> The stack size is the approximate number of bytes of address space
1071 * that the Java virtual machine is to allocate for the thread's stack. The
1072 * effect is highly platform dependent and the Java virtual machine is free
1073 * to treat the {@code stackSize} parameter as a "suggestion". If the value
1074 * is unreasonably low for the platform then a platform specific minimum
1075 * may be used. If the value is unreasonably high then a platform specific
1076 * maximum may be used. A value of zero is always ignored.
1077 *
1078 * @param stackSize the desired stack size
1079 * @return this builder
1080 * @throws IllegalArgumentException if the stack size is negative
1081 */
1082 OfPlatform stackSize(long stackSize);
1083 }
1084
1085 /**
1086 * A builder for creating a virtual {@link Thread} or {@link ThreadFactory}
1087 * that creates virtual threads.
1088 *
1089 * <p> Unless otherwise specified, passing a null argument to a method in
1090 * this interface causes a {@code NullPointerException} to be thrown.
1091 *
1092 * @see Thread#ofVirtual()
1093 * @since 21
1094 */
1095 sealed interface OfVirtual extends Builder
1096 permits ThreadBuilders.VirtualThreadBuilder {
1097
1098 @Override OfVirtual name(String name);
1099
1100 /**
1101 * @throws IllegalArgumentException {@inheritDoc}
1102 */
1103 @Override OfVirtual name(String prefix, long start);
1104
1105 @Override OfVirtual inheritInheritableThreadLocals(boolean inherit);
1106 @Override OfVirtual uncaughtExceptionHandler(UncaughtExceptionHandler ueh);
1107
1108 /**
1109 * Sets the scheduler.
1110 *
1111 * The thread will be scheduled by the Java virtual machine with the given
1112 * scheduler. The scheduler's {@link VirtualThreadScheduler#execute(Thread, Runnable)}
1113 * method may be invoked in the context of a virtual thread. The scheduler
1114 * must arrange to execute the {@code Runnable}'s {@code run} method on a
1115 * platform thread. Attempting to execute the run method in a virtual thread
1116 * causes {@link WrongThreadException} to be thrown.
1117 *
1118 * The {@code execute} method may be invoked at sensitive times (e.g. when
1119 * unparking a thread) so care should be taken to not directly execute the
1120 * task on the <em>current thread</em>.
1121 *
1122 * @param scheduler the scheduler
1123 * @return this builder
1124 * @throws UnsupportedOperationException if scheduling virtual threads to a
1125 * user-provided scheduler is not supported by this VM
1126 *
1127 * @since 99
1128 */
1129 @CallerSensitive
1130 @Restricted
1131 OfVirtual scheduler(VirtualThreadScheduler scheduler);
1132 }
1133 }
1134
1135 /**
1136 * Throws CloneNotSupportedException as a Thread can not be meaningfully
1137 * cloned. Construct a new Thread instead.
1138 *
1139 * @throws CloneNotSupportedException
1140 * always
1141 */
1142 @Override
1143 protected Object clone() throws CloneNotSupportedException {
1144 throw new CloneNotSupportedException();
1145 }
1146
1147 /**
1148 * Helper class for auto-numbering platform threads. The numbers start at
1149 * 0 and are separate from the thread identifier for historical reasons.
1150 */
1151 private static class ThreadNumbering {
1152 private static final Unsafe U;
1153 private static final Object NEXT_BASE;
1154 private static final long NEXT_OFFSET;
1155 static {
1156 U = Unsafe.getUnsafe();
1157 try {
1158 Field nextField = ThreadNumbering.class.getDeclaredField("next");
1159 NEXT_BASE = U.staticFieldBase(nextField);
1160 NEXT_OFFSET = U.staticFieldOffset(nextField);
1161 } catch (NoSuchFieldException e) {
1162 throw new ExceptionInInitializerError(e);
1163 }
1164 }
1165 private static volatile int next;
1166 static int next() {
1167 return U.getAndAddInt(NEXT_BASE, NEXT_OFFSET, 1);
1168 }
1169 }
1170
1171 /**
1172 * Generates a thread name of the form {@code Thread-<n>}.
1173 */
1174 static String genThreadName() {
1175 return "Thread-" + ThreadNumbering.next();
1176 }
1177
1178 /**
1179 * Throws NullPointerException if the name is null. Avoids use of
1180 * Objects.requireNonNull in early startup.
1181 */
1182 private static String checkName(String name) {
1183 if (name == null)
1184 throw new NullPointerException("'name' is null");
1185 return name;
1186 }
1187
1188 /**
1189 * Initializes a new platform {@code Thread}. This constructor has the same
1190 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
1191 * {@code (null, null, gname)}, where {@code gname} is a newly generated
1192 * name. Automatically generated names are of the form
1193 * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
1194 *
1195 * <p> This constructor is only useful when extending {@code Thread} to
1196 * override the {@link #run()} method.
1197 *
1198 * @see <a href="#inheritance">Inheritance when creating threads</a>
1199 */
1200 public Thread() {
1201 this(null, null, 0, null, 0);
1202 }
1203
1204 /**
1205 * Initializes a new platform {@code Thread}. This constructor has the same
1206 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
1207 * {@code (null, task, gname)}, where {@code gname} is a newly generated
1208 * name. Automatically generated names are of the form
1209 * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
1210 *
1211 * <p> For a non-null task, invoking this constructor directly is equivalent to:
1212 * <pre>{@code Thread.ofPlatform().unstarted(task); }</pre>
1213 *
1214 * @param task
1215 * the object whose {@code run} method is invoked when this thread
1216 * is started. If {@code null}, this classes {@code run} method does
1217 * nothing.
1218 *
1219 * @see <a href="#inheritance">Inheritance when creating threads</a>
1220 */
1221 public Thread(Runnable task) {
1222 this(null, null, 0, task, 0);
1223 }
1224
1225 /**
1226 * Initializes a new platform {@code Thread}. This constructor has the same
1227 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
1228 * {@code (group, task, gname)}, where {@code gname} is a newly generated
1229 * name. Automatically generated names are of the form
1230 * {@code "Thread-"+}<i>n</i>, where <i>n</i> is an integer.
1231 *
1232 * <p> For a non-null group and task, invoking this constructor directly is
1233 * equivalent to:
1234 * <pre>{@code Thread.ofPlatform().group(group).unstarted(task); }</pre>
1235 *
1236 * @param group
1237 * the thread group. If {@code null} the group
1238 * is set to the current thread's thread group.
1239 *
1240 * @param task
1241 * the object whose {@code run} method is invoked when this thread
1242 * is started. If {@code null}, this thread's run method is invoked.
1243 *
1244 * @see <a href="#inheritance">Inheritance when creating threads</a>
1245 */
1246 public Thread(ThreadGroup group, Runnable task) {
1247 this(group, null, 0, task, 0);
1248 }
1249
1250 /**
1251 * Initializes a new platform {@code Thread}. This constructor has the same
1252 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
1253 * {@code (null, null, name)}.
1254 *
1255 * <p> This constructor is only useful when extending {@code Thread} to
1256 * override the {@link #run()} method.
1257 *
1258 * @param name
1259 * the name of the new thread
1260 *
1261 * @see <a href="#inheritance">Inheritance when creating threads</a>
1262 */
1263 public Thread(String name) {
1264 this(null, checkName(name), 0, null, 0);
1265 }
1266
1267 /**
1268 * Initializes a new platform {@code Thread}. This constructor has the same
1269 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
1270 * {@code (group, null, name)}.
1271 *
1272 * <p> This constructor is only useful when extending {@code Thread} to
1273 * override the {@link #run()} method.
1274 *
1275 * @param group
1276 * the thread group. If {@code null}, the group
1277 * is set to the current thread's thread group.
1278 *
1279 * @param name
1280 * the name of the new thread
1281 *
1282 * @see <a href="#inheritance">Inheritance when creating threads</a>
1283 */
1284 public Thread(ThreadGroup group, String name) {
1285 this(group, checkName(name), 0, null, 0);
1286 }
1287
1288 /**
1289 * Initializes a new platform {@code Thread}. This constructor has the same
1290 * effect as {@linkplain #Thread(ThreadGroup,Runnable,String) Thread}
1291 * {@code (null, task, name)}.
1292 *
1293 * <p> For a non-null task and name, invoking this constructor directly is
1294 * equivalent to:
1295 * <pre>{@code Thread.ofPlatform().name(name).unstarted(task); }</pre>
1296 *
1297 * @param task
1298 * the object whose {@code run} method is invoked when this thread
1299 * is started. If {@code null}, this thread's run method is invoked.
1300 *
1301 * @param name
1302 * the name of the new thread
1303 *
1304 * @see <a href="#inheritance">Inheritance when creating threads</a>
1305 */
1306 public Thread(Runnable task, String name) {
1307 this(null, checkName(name), 0, task, 0);
1308 }
1309
1310 /**
1311 * Initializes a new platform {@code Thread} so that it has {@code task}
1312 * as its run object, has the specified {@code name} as its name,
1313 * and belongs to the thread group referred to by {@code group}.
1314 *
1315 * <p>The priority of the newly created thread is the smaller of
1316 * priority of the thread creating it and the maximum permitted
1317 * priority of the thread group. The method {@linkplain #setPriority
1318 * setPriority} may be used to change the priority to a new value.
1319 *
1320 * <p>The newly created thread is initially marked as being a daemon
1321 * thread if and only if the thread creating it is currently marked
1322 * as a daemon thread. The method {@linkplain #setDaemon setDaemon}
1323 * may be used to change whether or not a thread is a daemon.
1324 *
1325 * <p>For a non-null group, task, and name, invoking this constructor directly
1326 * is equivalent to:
1327 * <pre>{@code Thread.ofPlatform().group(group).name(name).unstarted(task); }</pre>
1328 *
1329 * @param group
1330 * the thread group. If {@code null}, the group
1331 * is set to the current thread's thread group.
1332 *
1333 * @param task
1334 * the object whose {@code run} method is invoked when this thread
1335 * is started. If {@code null}, this thread's run method is invoked.
1336 *
1337 * @param name
1338 * the name of the new thread
1339 *
1340 * @see <a href="#inheritance">Inheritance when creating threads</a>
1341 */
1342 public Thread(ThreadGroup group, Runnable task, String name) {
1343 this(group, checkName(name), 0, task, 0);
1344 }
1345
1346 /**
1347 * Initializes a new platform {@code Thread} so that it has {@code task}
1348 * as its run object, has the specified {@code name} as its name,
1349 * and belongs to the thread group referred to by {@code group}, and has
1350 * the specified <i>stack size</i>.
1351 *
1352 * <p>This constructor is identical to {@link
1353 * #Thread(ThreadGroup,Runnable,String)} with the exception of the fact
1354 * that it allows the thread stack size to be specified. The stack size
1355 * is the approximate number of bytes of address space that the virtual
1356 * machine is to allocate for this thread's stack. <b>The effect of the
1357 * {@code stackSize} parameter, if any, is highly platform dependent.</b>
1358 *
1359 * <p>On some platforms, specifying a higher value for the
1360 * {@code stackSize} parameter may allow a thread to achieve greater
1361 * recursion depth before throwing a {@link StackOverflowError}.
1362 * Similarly, specifying a lower value may allow a greater number of
1363 * threads to exist concurrently without throwing an {@link
1364 * OutOfMemoryError} (or other internal error). The details of
1365 * the relationship between the value of the {@code stackSize} parameter
1366 * and the maximum recursion depth and concurrency level are
1367 * platform-dependent. <b>On some platforms, the value of the
1368 * {@code stackSize} parameter may have no effect whatsoever.</b>
1369 *
1370 * <p>The virtual machine is free to treat the {@code stackSize}
1371 * parameter as a suggestion. If the specified value is unreasonably low
1372 * for the platform, the virtual machine may instead use some
1373 * platform-specific minimum value; if the specified value is unreasonably
1374 * high, the virtual machine may instead use some platform-specific
1375 * maximum. Likewise, the virtual machine is free to round the specified
1376 * value up or down as it sees fit (or to ignore it completely).
1377 *
1378 * <p>Specifying a value of zero for the {@code stackSize} parameter will
1379 * cause this constructor to behave exactly like the
1380 * {@code Thread(ThreadGroup, Runnable, String)} constructor.
1381 *
1382 * <p><i>Due to the platform-dependent nature of the behavior of this
1383 * constructor, extreme care should be exercised in its use.
1384 * The thread stack size necessary to perform a given computation will
1385 * likely vary from one JRE implementation to another. In light of this
1386 * variation, careful tuning of the stack size parameter may be required,
1387 * and the tuning may need to be repeated for each JRE implementation on
1388 * which an application is to run.</i>
1389 *
1390 * <p>Implementation note: Java platform implementers are encouraged to
1391 * document their implementation's behavior with respect to the
1392 * {@code stackSize} parameter.
1393 *
1394 * <p>For a non-null group, task, and name, invoking this constructor directly
1395 * is equivalent to:
1396 * <pre>{@code Thread.ofPlatform().group(group).name(name).stackSize(stackSize).unstarted(task); }</pre>
1397 *
1398 * @param group
1399 * the thread group. If {@code null}, the group
1400 * is set to the current thread's thread group.
1401 *
1402 * @param task
1403 * the object whose {@code run} method is invoked when this thread
1404 * is started. If {@code null}, this thread's run method is invoked.
1405 *
1406 * @param name
1407 * the name of the new thread
1408 *
1409 * @param stackSize
1410 * the desired stack size for the new thread, or zero to indicate
1411 * that this parameter is to be ignored.
1412 *
1413 * @since 1.4
1414 * @see <a href="#inheritance">Inheritance when creating threads</a>
1415 */
1416 public Thread(ThreadGroup group, Runnable task, String name, long stackSize) {
1417 this(group, checkName(name), 0, task, stackSize);
1418 }
1419
1420 /**
1421 * Initializes a new platform {@code Thread} so that it has {@code task}
1422 * as its run object, has the specified {@code name} as its name,
1423 * belongs to the thread group referred to by {@code group}, has
1424 * the specified {@code stackSize}, and inherits initial values for
1425 * {@linkplain InheritableThreadLocal inheritable thread-local} variables
1426 * if {@code inheritThreadLocals} is {@code true}.
1427 *
1428 * <p> This constructor is identical to {@link
1429 * #Thread(ThreadGroup,Runnable,String,long)} with the added ability to
1430 * suppress, or not, the inheriting of initial values for inheritable
1431 * thread-local variables from the constructing thread. This allows for
1432 * finer grain control over inheritable thread-locals. Care must be taken
1433 * when passing a value of {@code false} for {@code inheritThreadLocals},
1434 * as it may lead to unexpected behavior if the new thread executes code
1435 * that expects a specific thread-local value to be inherited.
1436 *
1437 * <p> Specifying a value of {@code true} for the {@code inheritThreadLocals}
1438 * parameter will cause this constructor to behave exactly like the
1439 * {@code Thread(ThreadGroup, Runnable, String, long)} constructor.
1440 *
1441 * <p> For a non-null group, task, and name, invoking this constructor directly
1442 * is equivalent to:
1443 * <pre>{@code Thread.ofPlatform()
1444 * .group(group)
1445 * .name(name)
1446 * .stackSize(stackSize)
1447 * .inheritInheritableThreadLocals(inheritInheritableThreadLocals)
1448 * .unstarted(task); }</pre>
1449 *
1450 * @param group
1451 * the thread group. If {@code null}, the group
1452 * is set to the current thread's thread group.
1453 *
1454 * @param task
1455 * the object whose {@code run} method is invoked when this thread
1456 * is started. If {@code null}, this thread's run method is invoked.
1457 *
1458 * @param name
1459 * the name of the new thread
1460 *
1461 * @param stackSize
1462 * the desired stack size for the new thread, or zero to indicate
1463 * that this parameter is to be ignored
1464 *
1465 * @param inheritInheritableThreadLocals
1466 * if {@code true}, inherit initial values for inheritable
1467 * thread-locals from the constructing thread, otherwise no initial
1468 * values are inherited
1469 *
1470 * @since 9
1471 * @see <a href="#inheritance">Inheritance when creating threads</a>
1472 */
1473 public Thread(ThreadGroup group, Runnable task, String name,
1474 long stackSize, boolean inheritInheritableThreadLocals) {
1475 this(group, checkName(name),
1476 (inheritInheritableThreadLocals ? 0 : NO_INHERIT_THREAD_LOCALS),
1477 task, stackSize);
1478 }
1479
1480 /**
1481 * Creates a virtual thread to execute a task and schedules it to execute.
1482 * The thread is scheduled by the default virtual thread scheduler.
1483 *
1484 * <p> This method is equivalent to:
1485 * <pre>{@code Thread.ofVirtual().start(task); }</pre>
1486 *
1487 * @param task the object to run when the thread executes
1488 * @return a new, and started, virtual thread
1489 * @see <a href="#inheritance">Inheritance when creating threads</a>
1490 * @since 21
1491 */
1492 public static Thread startVirtualThread(Runnable task) {
1493 Objects.requireNonNull(task);
1494 var thread = ThreadBuilders.newVirtualThread(null, null, 0, task);
1495 thread.start();
1496 return thread;
1497 }
1498
1499 /**
1500 * Returns {@code true} if this thread is a virtual thread. A virtual thread
1501 * is scheduled by the Java virtual machine rather than the operating system.
1502 *
1503 * @return {@code true} if this thread is a virtual thread
1504 *
1505 * @since 21
1506 */
1507 public final boolean isVirtual() {
1508 return (this instanceof BaseVirtualThread);
1509 }
1510
1511 /**
1512 * Schedules this thread to begin execution. The thread will execute
1513 * independently of the current thread.
1514 *
1515 * <p> A thread can be started at most once. In particular, a thread can not
1516 * be restarted after it has terminated.
1517 *
1518 * @throws IllegalThreadStateException if the thread was already started
1519 */
1520 public void start() {
1521 synchronized (this) {
1522 // zero status corresponds to state "NEW".
1523 if (holder.threadStatus != 0)
1524 throw new IllegalThreadStateException();
1525 start0();
1526 }
1527 }
1528
1529 /**
1530 * Schedules this thread to begin execution in the given thread container.
1531 * @throws IllegalStateException if the container is shutdown or closed
1532 * @throws IllegalThreadStateException if the thread has already been started
1533 */
1534 void start(ThreadContainer container) {
1535 synchronized (this) {
1536 // zero status corresponds to state "NEW".
1537 if (holder.threadStatus != 0)
1538 throw new IllegalThreadStateException();
1539
1540 // bind thread to container
1541 if (this.container != null)
1542 throw new IllegalThreadStateException();
1543 setThreadContainer(container);
1544
1545 // start thread
1546 boolean started = false;
1547 container.add(this); // may throw
1548 try {
1549 // scoped values may be inherited
1550 inheritScopedValueBindings(container);
1551
1552 start0();
1553 started = true;
1554 } finally {
1555 if (!started) {
1556 container.remove(this);
1557 }
1558 }
1559 }
1560 }
1561
1562 private native void start0();
1563
1564 /**
1565 * This method is run by the thread when it executes. Subclasses of {@code
1566 * Thread} may override this method.
1567 *
1568 * <p> This method is not intended to be invoked directly. If this thread is a
1569 * platform thread created with a {@link Runnable} task then invoking this method
1570 * will invoke the task's {@code run} method. If this thread is a virtual thread
1571 * then invoking this method directly does nothing.
1572 *
1573 * @implSpec The default implementation executes the {@link Runnable} task that
1574 * the {@code Thread} was created with. If the thread was created without a task
1575 * then this method does nothing.
1576 */
1577 @Override
1578 public void run() {
1579 Runnable task = holder.task;
1580 if (task != null) {
1581 Object bindings = scopedValueBindings();
1582 runWith(bindings, task);
1583 }
1584 }
1585
1586 /**
1587 * The VM recognizes this method as special, so any changes to the
1588 * name or signature require corresponding changes in
1589 * JVM_FindScopedValueBindings().
1590 */
1591 @Hidden
1592 @ForceInline
1593 final void runWith(Object bindings, Runnable op) {
1594 ensureMaterializedForStackWalk(bindings);
1595 op.run();
1596 Reference.reachabilityFence(bindings);
1597 }
1598
1599 /**
1600 * Null out reference after Thread termination.
1601 */
1602 void clearReferences() {
1603 threadLocals = null;
1604 inheritableThreadLocals = null;
1605 if (uncaughtExceptionHandler != null)
1606 uncaughtExceptionHandler = null;
1607 if (nioBlocker != null)
1608 nioBlocker = null;
1609 }
1610
1611 /**
1612 * This method is called by the VM to give a Thread
1613 * a chance to clean up before it actually exits.
1614 */
1615 private void exit() {
1616 try {
1617 // pop any remaining scopes from the stack, this may block
1618 if (headStackableScopes != null) {
1619 StackableScope.popAll();
1620 }
1621 } finally {
1622 // notify container that thread is exiting
1623 ThreadContainer container = threadContainer();
1624 if (container != null) {
1625 container.remove(this);
1626 }
1627 }
1628
1629 try {
1630 if (terminatingThreadLocals() != null) {
1631 TerminatingThreadLocal.threadTerminated();
1632 }
1633 } finally {
1634 clearReferences();
1635 }
1636 }
1637
1638 /**
1639 * Throws {@code UnsupportedOperationException}.
1640 *
1641 * @throws UnsupportedOperationException always
1642 *
1643 * @deprecated This method was originally specified to "stop" a victim
1644 * thread by causing the victim thread to throw a {@link ThreadDeath}.
1645 * It was inherently unsafe. Stopping a thread caused it to unlock
1646 * all of the monitors that it had locked (as a natural consequence
1647 * of the {@code ThreadDeath} exception propagating up the stack). If
1648 * any of the objects previously protected by these monitors were in
1649 * an inconsistent state, the damaged objects became visible to
1650 * other threads, potentially resulting in arbitrary behavior.
1651 * Usages of {@code stop} should be replaced by code that simply
1652 * modifies some variable to indicate that the target thread should
1653 * stop running. The target thread should check this variable
1654 * regularly, and return from its run method in an orderly fashion
1655 * if the variable indicates that it is to stop running. If the
1656 * target thread waits for long periods (on a condition variable,
1657 * for example), the {@code interrupt} method should be used to
1658 * interrupt the wait.
1659 * For more information, see
1660 * <a href="{@docRoot}/java.base/java/lang/doc-files/threadPrimitiveDeprecation.html">Why
1661 * is Thread.stop deprecated and the ability to stop a thread removed?</a>.
1662 */
1663 @Deprecated(since="1.2", forRemoval=true)
1664 public final void stop() {
1665 throw new UnsupportedOperationException();
1666 }
1667
1668 /**
1669 * Interrupts this thread.
1670 *
1671 * <p> If this thread is blocked in an invocation of the {@link
1672 * Object#wait() wait()}, {@link Object#wait(long) wait(long)}, or {@link
1673 * Object#wait(long, int) wait(long, int)} methods of the {@link Object}
1674 * class, or of the {@link #join()}, {@link #join(long)}, {@link
1675 * #join(long, int)}, {@link #sleep(long)}, or {@link #sleep(long, int)}
1676 * methods of this class, then its interrupt status will be cleared and it
1677 * will receive an {@link InterruptedException}.
1678 *
1679 * <p> If this thread is blocked in an I/O operation upon an {@link
1680 * java.nio.channels.InterruptibleChannel InterruptibleChannel}
1681 * then the channel will be closed, the thread's interrupt
1682 * status will be set, and the thread will receive a {@link
1683 * java.nio.channels.ClosedByInterruptException}.
1684 *
1685 * <p> If this thread is blocked in a {@link java.nio.channels.Selector}
1686 * then the thread's interrupt status will be set and it will return
1687 * immediately from the selection operation, possibly with a non-zero
1688 * value, just as if the selector's {@link
1689 * java.nio.channels.Selector#wakeup wakeup} method were invoked.
1690 *
1691 * <p> If none of the previous conditions hold then this thread's interrupt
1692 * status will be set. </p>
1693 *
1694 * <p> Interrupting a thread that is not alive need not have any effect.
1695 *
1696 * @implNote In the JDK Reference Implementation, interruption of a thread
1697 * that is not alive still records that the interrupt request was made and
1698 * will report it via {@link #interrupted()} and {@link #isInterrupted()}.
1699 */
1700 public void interrupt() {
1701 // Setting the interrupt status must be done before reading nioBlocker.
1702 interrupted = true;
1703 interrupt0(); // inform VM of interrupt
1704
1705 // thread may be blocked in an I/O operation
1706 if (this != Thread.currentThread()) {
1707 Interruptible blocker;
1708 synchronized (interruptLock) {
1709 blocker = nioBlocker;
1710 if (blocker != null) {
1711 blocker.interrupt(this);
1712 }
1713 }
1714 if (blocker != null) {
1715 blocker.postInterrupt();
1716 }
1717 }
1718 }
1719
1720 /**
1721 * Tests whether the current thread has been interrupted. The
1722 * <i>interrupted status</i> of the thread is cleared by this method. In
1723 * other words, if this method were to be called twice in succession, the
1724 * second call would return false (unless the current thread were
1725 * interrupted again, after the first call had cleared its interrupted
1726 * status and before the second call had examined it).
1727 *
1728 * @return {@code true} if the current thread has been interrupted;
1729 * {@code false} otherwise.
1730 * @see #isInterrupted()
1731 */
1732 public static boolean interrupted() {
1733 return currentThread().getAndClearInterrupt();
1734 }
1735
1736 /**
1737 * Tests whether this thread has been interrupted. The <i>interrupted
1738 * status</i> of the thread is unaffected by this method.
1739 *
1740 * @return {@code true} if this thread has been interrupted;
1741 * {@code false} otherwise.
1742 * @see #interrupted()
1743 */
1744 public boolean isInterrupted() {
1745 return interrupted;
1746 }
1747
1748 final void setInterrupt() {
1749 // assert Thread.currentCarrierThread() == this;
1750 if (!interrupted) {
1751 interrupted = true;
1752 interrupt0(); // inform VM of interrupt
1753 }
1754 }
1755
1756 final void clearInterrupt() {
1757 // assert Thread.currentCarrierThread() == this;
1758 if (interrupted) {
1759 interrupted = false;
1760 clearInterruptEvent();
1761 }
1762 }
1763
1764 boolean getAndClearInterrupt() {
1765 boolean oldValue = interrupted;
1766 // We may have been interrupted the moment after we read the field,
1767 // so only clear the field if we saw that it was set and will return
1768 // true; otherwise we could lose an interrupt.
1769 if (oldValue) {
1770 interrupted = false;
1771 clearInterruptEvent();
1772 }
1773 return oldValue;
1774 }
1775
1776 /**
1777 * Tests if this thread is alive. A thread is alive if it has
1778 * been started and has not yet terminated.
1779 *
1780 * @return {@code true} if this thread is alive;
1781 * {@code false} otherwise.
1782 */
1783 public final boolean isAlive() {
1784 return alive();
1785 }
1786
1787 /**
1788 * Returns true if this thread is alive.
1789 * This method is non-final so it can be overridden.
1790 */
1791 boolean alive() {
1792 return eetop != 0;
1793 }
1794
1795 /**
1796 * Changes the priority of this thread.
1797 *
1798 * For platform threads, the priority is set to the smaller of the specified
1799 * {@code newPriority} and the maximum permitted priority of the thread's
1800 * {@linkplain ThreadGroup thread group}.
1801 *
1802 * The priority of a virtual thread is always {@link Thread#NORM_PRIORITY}
1803 * and {@code newPriority} is ignored.
1804 *
1805 * @param newPriority the new thread priority
1806 * @throws IllegalArgumentException if the priority is not in the
1807 * range {@code MIN_PRIORITY} to {@code MAX_PRIORITY}.
1808 * @see #setPriority(int)
1809 * @see ThreadGroup#getMaxPriority()
1810 */
1811 public final void setPriority(int newPriority) {
1812 if (newPriority > MAX_PRIORITY || newPriority < MIN_PRIORITY) {
1813 throw new IllegalArgumentException();
1814 }
1815 if (!isVirtual()) {
1816 priority(newPriority);
1817 }
1818 }
1819
1820 void priority(int newPriority) {
1821 ThreadGroup g = holder.group;
1822 if (g != null) {
1823 int maxPriority = g.getMaxPriority();
1824 if (newPriority > maxPriority) {
1825 newPriority = maxPriority;
1826 }
1827 setPriority0(holder.priority = newPriority);
1828 }
1829 }
1830
1831 /**
1832 * Returns this thread's priority.
1833 *
1834 * <p> The priority of a virtual thread is always {@link Thread#NORM_PRIORITY}.
1835 *
1836 * @return this thread's priority.
1837 * @see #setPriority
1838 */
1839 public final int getPriority() {
1840 if (isVirtual()) {
1841 return Thread.NORM_PRIORITY;
1842 } else {
1843 return holder.priority;
1844 }
1845 }
1846
1847 /**
1848 * Changes the name of this thread to be equal to the argument {@code name}.
1849 *
1850 * @implNote In the JDK Reference Implementation, if this thread is the
1851 * current thread, and it's a platform thread that was not attached to the
1852 * VM with the Java Native Interface
1853 * <a href="{@docRoot}/../specs/jni/invocation.html#attachcurrentthread">
1854 * AttachCurrentThread</a> function, then this method will set the operating
1855 * system thread name. This may be useful for debugging and troubleshooting
1856 * purposes.
1857 *
1858 * @param name the new name for this thread.
1859 *
1860 * @spec jni/index.html Java Native Interface Specification
1861 * @see #getName
1862 */
1863 public final synchronized void setName(String name) {
1864 if (name == null) {
1865 throw new NullPointerException("name cannot be null");
1866 }
1867 this.name = name;
1868 if (!isVirtual() && Thread.currentThread() == this) {
1869 setNativeName(name);
1870 }
1871 }
1872
1873 /**
1874 * Returns this thread's name.
1875 *
1876 * @return this thread's name.
1877 * @see #setName(String)
1878 */
1879 public final String getName() {
1880 return name;
1881 }
1882
1883 /**
1884 * Returns the thread's thread group or {@code null} if the thread has
1885 * terminated.
1886 *
1887 * <p> The thread group returned for a virtual thread is the special
1888 * <a href="ThreadGroup.html#virtualthreadgroup"><em>ThreadGroup for
1889 * virtual threads</em></a>.
1890 *
1891 * @return this thread's thread group or {@code null}
1892 */
1893 public final ThreadGroup getThreadGroup() {
1894 if (isTerminated()) {
1895 return null;
1896 } else {
1897 return isVirtual() ? virtualThreadGroup() : holder.group;
1898 }
1899 }
1900
1901 /**
1902 * Returns an estimate of the number of {@linkplain #isAlive() live}
1903 * platform threads in the current thread's thread group and its subgroups.
1904 * Virtual threads are not included in the estimate.
1905 *
1906 * <p> The value returned is only an estimate because the number of
1907 * threads may change dynamically while this method traverses internal
1908 * data structures, and might be affected by the presence of certain
1909 * system threads. This method is intended primarily for debugging
1910 * and monitoring purposes.
1911 *
1912 * @return an estimate of the number of live platform threads in the
1913 * current thread's thread group and in any other thread group
1914 * that has the current thread's thread group as an ancestor
1915 */
1916 public static int activeCount() {
1917 return currentThread().getThreadGroup().activeCount();
1918 }
1919
1920 /**
1921 * Copies into the specified array every {@linkplain #isAlive() live}
1922 * platform thread in the current thread's thread group and its subgroups.
1923 * This method simply invokes the {@link java.lang.ThreadGroup#enumerate(Thread[])}
1924 * method of the current thread's thread group. Virtual threads are
1925 * not enumerated by this method.
1926 *
1927 * <p> An application might use the {@linkplain #activeCount activeCount}
1928 * method to get an estimate of how big the array should be, however
1929 * <i>if the array is too short to hold all the threads, the extra threads
1930 * are silently ignored.</i> If it is critical to obtain every live
1931 * thread in the current thread's thread group and its subgroups, the
1932 * invoker should verify that the returned int value is strictly less
1933 * than the length of {@code tarray}.
1934 *
1935 * <p> Due to the inherent race condition in this method, it is recommended
1936 * that the method only be used for debugging and monitoring purposes.
1937 *
1938 * @param tarray
1939 * an array into which to put the list of threads
1940 *
1941 * @return the number of threads put into the array
1942 */
1943 public static int enumerate(Thread[] tarray) {
1944 return currentThread().getThreadGroup().enumerate(tarray);
1945 }
1946
1947 /**
1948 * Waits at most {@code millis} milliseconds for this thread to terminate.
1949 * A timeout of {@code 0} means to wait forever.
1950 * This method returns immediately, without waiting, if the thread has not
1951 * been {@link #start() started}.
1952 *
1953 * @implNote
1954 * For platform threads, the implementation uses a loop of {@code this.wait}
1955 * calls conditioned on {@code this.isAlive}. As a thread terminates the
1956 * {@code this.notifyAll} method is invoked. It is recommended that
1957 * applications not use {@code wait}, {@code notify}, or
1958 * {@code notifyAll} on {@code Thread} instances.
1959 *
1960 * @param millis
1961 * the time to wait in milliseconds
1962 *
1963 * @throws IllegalArgumentException
1964 * if the value of {@code millis} is negative
1965 *
1966 * @throws InterruptedException
1967 * if any thread has interrupted the current thread. The
1968 * <i>interrupted status</i> of the current thread is
1969 * cleared when this exception is thrown.
1970 */
1971 public final void join(long millis) throws InterruptedException {
1972 if (millis < 0)
1973 throw new IllegalArgumentException("timeout value is negative");
1974
1975 if (this instanceof VirtualThread vthread) {
1976 if (isAlive()) {
1977 long nanos = MILLISECONDS.toNanos(millis);
1978 vthread.joinNanos(nanos);
1979 }
1980 return;
1981 }
1982
1983 synchronized (this) {
1984 if (millis > 0) {
1985 if (isAlive()) {
1986 final long startTime = System.nanoTime();
1987 long delay = millis;
1988 do {
1989 wait(delay);
1990 } while (isAlive() && (delay = millis -
1991 NANOSECONDS.toMillis(System.nanoTime() - startTime)) > 0);
1992 }
1993 } else {
1994 while (isAlive()) {
1995 wait(0);
1996 }
1997 }
1998 }
1999 }
2000
2001 /**
2002 * Waits at most {@code millis} milliseconds plus
2003 * {@code nanos} nanoseconds for this thread to terminate.
2004 * If both arguments are {@code 0}, it means to wait forever.
2005 * This method returns immediately, without waiting, if the thread has not
2006 * been {@link #start() started}.
2007 *
2008 * @implNote
2009 * For platform threads, the implementation uses a loop of {@code this.wait}
2010 * calls conditioned on {@code this.isAlive}. As a thread terminates the
2011 * {@code this.notifyAll} method is invoked. It is recommended that
2012 * applications not use {@code wait}, {@code notify}, or
2013 * {@code notifyAll} on {@code Thread} instances.
2014 *
2015 * @param millis
2016 * the time to wait in milliseconds
2017 *
2018 * @param nanos
2019 * {@code 0-999999} additional nanoseconds to wait
2020 *
2021 * @throws IllegalArgumentException
2022 * if the value of {@code millis} is negative, or the value
2023 * of {@code nanos} is not in the range {@code 0-999999}
2024 *
2025 * @throws InterruptedException
2026 * if any thread has interrupted the current thread. The
2027 * <i>interrupted status</i> of the current thread is
2028 * cleared when this exception is thrown.
2029 */
2030 public final void join(long millis, int nanos) throws InterruptedException {
2031 if (millis < 0) {
2032 throw new IllegalArgumentException("timeout value is negative");
2033 }
2034
2035 if (nanos < 0 || nanos > 999999) {
2036 throw new IllegalArgumentException("nanosecond timeout value out of range");
2037 }
2038
2039 if (this instanceof VirtualThread vthread) {
2040 if (isAlive()) {
2041 // convert arguments to a total in nanoseconds
2042 long totalNanos = MILLISECONDS.toNanos(millis);
2043 totalNanos += Math.min(Long.MAX_VALUE - totalNanos, nanos);
2044 vthread.joinNanos(totalNanos);
2045 }
2046 return;
2047 }
2048
2049 if (nanos > 0 && millis < Long.MAX_VALUE) {
2050 millis++;
2051 }
2052 join(millis);
2053 }
2054
2055 /**
2056 * Waits for this thread to terminate.
2057 *
2058 * <p> An invocation of this method behaves in exactly the same
2059 * way as the invocation
2060 *
2061 * <blockquote>
2062 * {@linkplain #join(long) join}{@code (0)}
2063 * </blockquote>
2064 *
2065 * @throws InterruptedException
2066 * if any thread has interrupted the current thread. The
2067 * <i>interrupted status</i> of the current thread is
2068 * cleared when this exception is thrown.
2069 */
2070 public final void join() throws InterruptedException {
2071 join(0);
2072 }
2073
2074 /**
2075 * Waits for this thread to terminate for up to the given waiting duration.
2076 *
2077 * <p> This method does not wait if the duration to wait is less than or
2078 * equal to zero. In this case, the method just tests if the thread has
2079 * terminated.
2080 *
2081 * @param duration
2082 * the maximum duration to wait
2083 *
2084 * @return {@code true} if the thread has terminated, {@code false} if the
2085 * thread has not terminated
2086 *
2087 * @throws InterruptedException
2088 * if the current thread is interrupted while waiting.
2089 * The <i>interrupted status</i> of the current thread is cleared
2090 * when this exception is thrown.
2091 *
2092 * @throws IllegalThreadStateException
2093 * if this thread has not been started.
2094 *
2095 * @since 19
2096 */
2097 public final boolean join(Duration duration) throws InterruptedException {
2098 long nanos = NANOSECONDS.convert(duration); // MAX_VALUE if > 292 years
2099
2100 Thread.State state = threadState();
2101 if (state == State.NEW)
2102 throw new IllegalThreadStateException("Thread not started");
2103 if (state == State.TERMINATED)
2104 return true;
2105 if (nanos <= 0)
2106 return false;
2107
2108 if (this instanceof VirtualThread vthread) {
2109 return vthread.joinNanos(nanos);
2110 }
2111
2112 // convert to milliseconds
2113 long millis = MILLISECONDS.convert(nanos, NANOSECONDS);
2114 if (nanos > NANOSECONDS.convert(millis, MILLISECONDS)) {
2115 millis += 1L;
2116 }
2117 join(millis);
2118 return isTerminated();
2119 }
2120
2121 /**
2122 * Prints a stack trace of the current thread to the standard error stream.
2123 * This method is useful for debugging.
2124 */
2125 public static void dumpStack() {
2126 new Exception("Stack trace").printStackTrace();
2127 }
2128
2129 /**
2130 * Marks this thread as either a <i>daemon</i> or <i>non-daemon</i> thread.
2131 * The <a href="Runtime.html#shutdown">shutdown sequence</a> begins when all
2132 * started non-daemon threads have terminated.
2133 *
2134 * <p> The daemon status of a virtual thread is always {@code true} and cannot be
2135 * changed by this method to {@code false}.
2136 *
2137 * <p> This method must be invoked before the thread is started. The behavior
2138 * of this method when the thread has terminated is not specified.
2139 *
2140 * @param on
2141 * if {@code true}, marks this thread as a daemon thread
2142 *
2143 * @throws IllegalArgumentException
2144 * if this is a virtual thread and {@code on} is false
2145 * @throws IllegalThreadStateException
2146 * if this thread is {@linkplain #isAlive alive}
2147 */
2148 public final void setDaemon(boolean on) {
2149 if (isVirtual() && !on)
2150 throw new IllegalArgumentException("'false' not legal for virtual threads");
2151 if (isAlive())
2152 throw new IllegalThreadStateException();
2153 if (!isVirtual())
2154 daemon(on);
2155 }
2156
2157 void daemon(boolean on) {
2158 holder.daemon = on;
2159 }
2160
2161 /**
2162 * Tests if this thread is a daemon thread.
2163 * The daemon status of a virtual thread is always {@code true}.
2164 *
2165 * @return {@code true} if this thread is a daemon thread;
2166 * {@code false} otherwise.
2167 * @see #setDaemon(boolean)
2168 */
2169 public final boolean isDaemon() {
2170 if (isVirtual()) {
2171 return true;
2172 } else {
2173 return holder.daemon;
2174 }
2175 }
2176
2177 /**
2178 * Does nothing.
2179 *
2180 * @deprecated This method originally determined if the currently running
2181 * thread had permission to modify this thread. This method was only useful
2182 * in conjunction with {@linkplain SecurityManager the Security Manager},
2183 * which is no longer supported. There is no replacement for the Security
2184 * Manager or this method.
2185 */
2186 @Deprecated(since="17", forRemoval=true)
2187 public final void checkAccess() { }
2188
2189 /**
2190 * Returns a string representation of this thread. The string representation
2191 * will usually include the thread's {@linkplain #threadId() identifier} and
2192 * name. The default implementation for platform threads includes the thread's
2193 * identifier, name, priority, and the name of the thread group.
2194 *
2195 * @return a string representation of this thread.
2196 */
2197 public String toString() {
2198 StringBuilder sb = new StringBuilder("Thread[#");
2199 sb.append(threadId());
2200 sb.append(",");
2201 sb.append(getName());
2202 sb.append(",");
2203 sb.append(getPriority());
2204 sb.append(",");
2205 ThreadGroup group = getThreadGroup();
2206 if (group != null)
2207 sb.append(group.getName());
2208 sb.append("]");
2209 return sb.toString();
2210 }
2211
2212 /**
2213 * Returns the context {@code ClassLoader} for this thread.
2214 * The context {@code ClassLoader} may be set by the creator of the thread
2215 * for use by code running in this thread when loading classes and resources.
2216 * If not {@linkplain #setContextClassLoader set}, the default is to inherit
2217 * the context class loader from the parent thread.
2218 *
2219 * <p> The context {@code ClassLoader} of the primordial thread is typically
2220 * set to the class loader used to load the application.
2221 *
2222 * @return the context {@code ClassLoader} for this thread, or {@code null}
2223 * indicating the system class loader (or, failing that, the
2224 * bootstrap class loader)
2225 *
2226 * @since 1.2
2227 */
2228 public ClassLoader getContextClassLoader() {
2229 return contextClassLoader;
2230 }
2231
2232 /**
2233 * Sets the context {@code ClassLoader} for this thread.
2234 *
2235 * <p> The context {@code ClassLoader} may be set by the creator of the thread
2236 * for use by code running in this thread when loading classes and resources.
2237 *
2238 * @param cl
2239 * the context ClassLoader for this Thread, or null indicating the
2240 * system class loader (or, failing that, the bootstrap class loader)
2241 *
2242 * @since 1.2
2243 */
2244 public void setContextClassLoader(ClassLoader cl) {
2245 contextClassLoader = cl;
2246 }
2247
2248 /**
2249 * Returns {@code true} if and only if the current thread holds the
2250 * monitor lock on the specified object.
2251 *
2252 * <p>This method is designed to allow a program to assert that
2253 * the current thread already holds a specified lock:
2254 * <pre>
2255 * assert Thread.holdsLock(obj);
2256 * </pre>
2257 *
2258 * @param obj the object on which to test lock ownership
2259 * @return {@code true} if the current thread holds the monitor lock on
2260 * the specified object.
2261 * @since 1.4
2262 */
2263 public static native boolean holdsLock(Object obj);
2264
2265 private static final StackTraceElement[] EMPTY_STACK_TRACE
2266 = new StackTraceElement[0];
2267
2268 /**
2269 * Returns an array of stack trace elements representing the stack dump
2270 * of this thread. This method will return a zero-length array if
2271 * this thread has not started, has started but has not yet been
2272 * scheduled to run by the system, or has terminated.
2273 * If the returned array is of non-zero length then the first element of
2274 * the array represents the top of the stack, which is the most recent
2275 * method invocation in the sequence. The last element of the array
2276 * represents the bottom of the stack, which is the least recent method
2277 * invocation in the sequence.
2278 *
2279 * <p>Some virtual machines may, under some circumstances, omit one
2280 * or more stack frames from the stack trace. In the extreme case,
2281 * a virtual machine that has no stack trace information concerning
2282 * this thread is permitted to return a zero-length array from this
2283 * method.
2284 *
2285 * @return an array of {@code StackTraceElement},
2286 * each represents one stack frame.
2287 *
2288 * @see Throwable#getStackTrace
2289 * @since 1.5
2290 */
2291 public StackTraceElement[] getStackTrace() {
2292 if (this != Thread.currentThread()) {
2293 // optimization so we do not call into the vm for threads that
2294 // have not yet started or have terminated
2295 if (!isAlive()) {
2296 return EMPTY_STACK_TRACE;
2297 }
2298 StackTraceElement[] stackTrace = asyncGetStackTrace();
2299 return (stackTrace != null) ? stackTrace : EMPTY_STACK_TRACE;
2300 } else {
2301 return (new Exception()).getStackTrace();
2302 }
2303 }
2304
2305 /**
2306 * Returns an array of stack trace elements representing the stack dump of
2307 * this thread. Returns null if the stack trace cannot be obtained. In
2308 * the default implementation, null is returned if the thread is a virtual
2309 * thread that is not mounted or the thread is a platform thread that has
2310 * terminated.
2311 */
2312 StackTraceElement[] asyncGetStackTrace() {
2313 Object stackTrace = getStackTrace0();
2314 if (stackTrace == null) {
2315 return null;
2316 }
2317 StackTraceElement[] stes = (StackTraceElement[]) stackTrace;
2318 if (stes.length == 0) {
2319 return null;
2320 } else {
2321 return StackTraceElement.of(stes);
2322 }
2323 }
2324
2325 private native Object getStackTrace0();
2326
2327 /**
2328 * Returns a map of stack traces for all live platform threads. The map
2329 * does not include virtual threads.
2330 * The map keys are threads and each map value is an array of
2331 * {@code StackTraceElement} that represents the stack dump
2332 * of the corresponding {@code Thread}.
2333 * The returned stack traces are in the format specified for
2334 * the {@link #getStackTrace getStackTrace} method.
2335 *
2336 * <p>The threads may be executing while this method is called.
2337 * The stack trace of each thread only represents a snapshot and
2338 * each stack trace may be obtained at different time. A zero-length
2339 * array will be returned in the map value if the virtual machine has
2340 * no stack trace information about a thread.
2341 *
2342 * @return a {@code Map} from {@code Thread} to an array of
2343 * {@code StackTraceElement} that represents the stack trace of
2344 * the corresponding thread.
2345 *
2346 * @see #getStackTrace
2347 * @see Throwable#getStackTrace
2348 *
2349 * @since 1.5
2350 */
2351 public static Map<Thread, StackTraceElement[]> getAllStackTraces() {
2352 // Get a snapshot of the list of all threads
2353 Thread[] threads = getThreads();
2354 StackTraceElement[][] traces = dumpThreads(threads);
2355 Map<Thread, StackTraceElement[]> m = HashMap.newHashMap(threads.length);
2356 for (int i = 0; i < threads.length; i++) {
2357 StackTraceElement[] stackTrace = traces[i];
2358 if (stackTrace != null) {
2359 m.put(threads[i], stackTrace);
2360 }
2361 // else terminated so we don't put it in the map
2362 }
2363 return m;
2364 }
2365
2366 /**
2367 * Return an array of all live threads.
2368 */
2369 static Thread[] getAllThreads() {
2370 return getThreads();
2371 }
2372
2373 private static native StackTraceElement[][] dumpThreads(Thread[] threads);
2374 private static native Thread[] getThreads();
2375
2376 /**
2377 * Returns the identifier of this Thread. The thread ID is a positive
2378 * {@code long} number generated when this thread was created.
2379 * The thread ID is unique and remains unchanged during its lifetime.
2380 *
2381 * @return this thread's ID
2382 *
2383 * @deprecated This method is not final and may be overridden to return a
2384 * value that is not the thread ID. Use {@link #threadId()} instead.
2385 *
2386 * @since 1.5
2387 */
2388 @Deprecated(since="19")
2389 public long getId() {
2390 return threadId();
2391 }
2392
2393 /**
2394 * Returns the identifier of this Thread. The thread ID is a positive
2395 * {@code long} number generated when this thread was created.
2396 * The thread ID is unique and remains unchanged during its lifetime.
2397 *
2398 * @return this thread's ID
2399 * @since 19
2400 */
2401 public final long threadId() {
2402 return tid;
2403 }
2404
2405 /**
2406 * A thread state. A thread can be in one of the following states:
2407 * <ul>
2408 * <li>{@link #NEW}<br>
2409 * A thread that has not yet started is in this state.
2410 * </li>
2411 * <li>{@link #RUNNABLE}<br>
2412 * A thread executing in the Java virtual machine is in this state.
2413 * </li>
2414 * <li>{@link #BLOCKED}<br>
2415 * A thread that is blocked waiting for a monitor lock
2416 * is in this state.
2417 * </li>
2418 * <li>{@link #WAITING}<br>
2419 * A thread that is waiting indefinitely for another thread to
2420 * perform a particular action is in this state.
2421 * </li>
2422 * <li>{@link #TIMED_WAITING}<br>
2423 * A thread that is waiting for another thread to perform an action
2424 * for up to a specified waiting time is in this state.
2425 * </li>
2426 * <li>{@link #TERMINATED}<br>
2427 * A thread that has exited is in this state.
2428 * </li>
2429 * </ul>
2430 *
2431 * <p>
2432 * A thread can be in only one state at a given point in time.
2433 * These states are virtual machine states which do not reflect
2434 * any operating system thread states.
2435 *
2436 * @since 1.5
2437 * @see #getState
2438 */
2439 public enum State {
2440 /**
2441 * Thread state for a thread which has not yet started.
2442 */
2443 NEW,
2444
2445 /**
2446 * Thread state for a runnable thread. A thread in the runnable
2447 * state is executing in the Java virtual machine but it may
2448 * be waiting for other resources from the operating system
2449 * such as processor.
2450 */
2451 RUNNABLE,
2452
2453 /**
2454 * Thread state for a thread blocked waiting for a monitor lock.
2455 * A thread in the blocked state is waiting for a monitor lock
2456 * to enter a synchronized block/method or
2457 * reenter a synchronized block/method after calling
2458 * {@link Object#wait() Object.wait}.
2459 */
2460 BLOCKED,
2461
2462 /**
2463 * Thread state for a waiting thread.
2464 * A thread is in the waiting state due to calling one of the
2465 * following methods:
2466 * <ul>
2467 * <li>{@link Object#wait() Object.wait} with no timeout</li>
2468 * <li>{@link #join() Thread.join} with no timeout</li>
2469 * <li>{@link LockSupport#park() LockSupport.park}</li>
2470 * </ul>
2471 *
2472 * <p>A thread in the waiting state is waiting for another thread to
2473 * perform a particular action.
2474 *
2475 * For example, a thread that has called {@code Object.wait()}
2476 * on an object is waiting for another thread to call
2477 * {@code Object.notify()} or {@code Object.notifyAll()} on
2478 * that object. A thread that has called {@code Thread.join()}
2479 * is waiting for a specified thread to terminate.
2480 */
2481 WAITING,
2482
2483 /**
2484 * Thread state for a waiting thread with a specified waiting time.
2485 * A thread is in the timed waiting state due to calling one of
2486 * the following methods with a specified positive waiting time:
2487 * <ul>
2488 * <li>{@link #sleep Thread.sleep}</li>
2489 * <li>{@link Object#wait(long) Object.wait} with timeout</li>
2490 * <li>{@link #join(long) Thread.join} with timeout</li>
2491 * <li>{@link LockSupport#parkNanos LockSupport.parkNanos}</li>
2492 * <li>{@link LockSupport#parkUntil LockSupport.parkUntil}</li>
2493 * </ul>
2494 */
2495 TIMED_WAITING,
2496
2497 /**
2498 * Thread state for a terminated thread.
2499 * The thread has completed execution.
2500 */
2501 TERMINATED;
2502 }
2503
2504 /**
2505 * Returns the state of this thread.
2506 * This method is designed for use in monitoring of the system state,
2507 * not for synchronization control.
2508 *
2509 * @return this thread's state.
2510 * @since 1.5
2511 */
2512 public State getState() {
2513 return threadState();
2514 }
2515
2516 /**
2517 * Returns the state of this thread.
2518 * This method can be used instead of getState as getState is not final and
2519 * so can be overridden to run arbitrary code.
2520 */
2521 State threadState() {
2522 return jdk.internal.misc.VM.toThreadState(holder.threadStatus);
2523 }
2524
2525 /**
2526 * Returns true if the thread has terminated.
2527 */
2528 boolean isTerminated() {
2529 return threadState() == State.TERMINATED;
2530 }
2531
2532 /**
2533 * Interface for handlers invoked when a {@code Thread} abruptly
2534 * terminates due to an uncaught exception.
2535 * <p>When a thread is about to terminate due to an uncaught exception
2536 * the Java Virtual Machine will query the thread for its
2537 * {@code UncaughtExceptionHandler} using
2538 * {@link #getUncaughtExceptionHandler} and will invoke the handler's
2539 * {@code uncaughtException} method, passing the thread and the
2540 * exception as arguments.
2541 * If a thread has not had its {@code UncaughtExceptionHandler}
2542 * explicitly set, then its {@code ThreadGroup} object acts as its
2543 * {@code UncaughtExceptionHandler}. If the {@code ThreadGroup} object
2544 * has no
2545 * special requirements for dealing with the exception, it can forward
2546 * the invocation to the {@linkplain #getDefaultUncaughtExceptionHandler
2547 * default uncaught exception handler}.
2548 *
2549 * @see #setDefaultUncaughtExceptionHandler
2550 * @see #setUncaughtExceptionHandler
2551 * @see ThreadGroup#uncaughtException
2552 * @since 1.5
2553 */
2554 @FunctionalInterface
2555 public interface UncaughtExceptionHandler {
2556 /**
2557 * Method invoked when the given thread terminates due to the
2558 * given uncaught exception.
2559 * <p>Any exception thrown by this method will be ignored by the
2560 * Java Virtual Machine.
2561 * @param t the thread
2562 * @param e the exception
2563 */
2564 void uncaughtException(Thread t, Throwable e);
2565 }
2566
2567 // null unless explicitly set
2568 private volatile UncaughtExceptionHandler uncaughtExceptionHandler;
2569
2570 // null unless explicitly set
2571 private static volatile UncaughtExceptionHandler defaultUncaughtExceptionHandler;
2572
2573 /**
2574 * Set the default handler invoked when a thread abruptly terminates
2575 * due to an uncaught exception, and no other handler has been defined
2576 * for that thread.
2577 *
2578 * <p>Uncaught exception handling is controlled first by the thread, then
2579 * by the thread's {@link ThreadGroup} object and finally by the default
2580 * uncaught exception handler. If the thread does not have an explicit
2581 * uncaught exception handler set, and the thread's thread group
2582 * (including parent thread groups) does not specialize its
2583 * {@code uncaughtException} method, then the default handler's
2584 * {@code uncaughtException} method will be invoked.
2585 * <p>By setting the default uncaught exception handler, an application
2586 * can change the way in which uncaught exceptions are handled (such as
2587 * logging to a specific device, or file) for those threads that would
2588 * already accept whatever "default" behavior the system
2589 * provided.
2590 *
2591 * <p>Note that the default uncaught exception handler should not usually
2592 * defer to the thread's {@code ThreadGroup} object, as that could cause
2593 * infinite recursion.
2594 *
2595 * @param ueh the object to use as the default uncaught exception handler.
2596 * If {@code null} then there is no default handler.
2597 *
2598 * @see #setUncaughtExceptionHandler
2599 * @see #getUncaughtExceptionHandler
2600 * @see ThreadGroup#uncaughtException
2601 * @since 1.5
2602 */
2603 public static void setDefaultUncaughtExceptionHandler(UncaughtExceptionHandler ueh) {
2604 defaultUncaughtExceptionHandler = ueh;
2605 }
2606
2607 /**
2608 * Returns the default handler invoked when a thread abruptly terminates
2609 * due to an uncaught exception. If the returned value is {@code null},
2610 * there is no default.
2611 * @since 1.5
2612 * @see #setDefaultUncaughtExceptionHandler
2613 * @return the default uncaught exception handler for all threads
2614 */
2615 public static UncaughtExceptionHandler getDefaultUncaughtExceptionHandler(){
2616 return defaultUncaughtExceptionHandler;
2617 }
2618
2619 /**
2620 * Returns the handler invoked when this thread abruptly terminates
2621 * due to an uncaught exception. If this thread has not had an
2622 * uncaught exception handler explicitly set then this thread's
2623 * {@code ThreadGroup} object is returned, unless this thread
2624 * has terminated, in which case {@code null} is returned.
2625 * @since 1.5
2626 * @return the uncaught exception handler for this thread
2627 */
2628 public UncaughtExceptionHandler getUncaughtExceptionHandler() {
2629 if (isTerminated()) {
2630 // uncaughtExceptionHandler may be set to null after thread terminates
2631 return null;
2632 } else {
2633 UncaughtExceptionHandler ueh = uncaughtExceptionHandler;
2634 return (ueh != null) ? ueh : getThreadGroup();
2635 }
2636 }
2637
2638 /**
2639 * Set the handler invoked when this thread abruptly terminates
2640 * due to an uncaught exception.
2641 * <p>A thread can take full control of how it responds to uncaught
2642 * exceptions by having its uncaught exception handler explicitly set.
2643 * If no such handler is set then the thread's {@code ThreadGroup}
2644 * object acts as its handler.
2645 * @param ueh the object to use as this thread's uncaught exception
2646 * handler. If {@code null} then this thread has no explicit handler.
2647 * @see #setDefaultUncaughtExceptionHandler
2648 * @see ThreadGroup#uncaughtException
2649 * @since 1.5
2650 */
2651 public void setUncaughtExceptionHandler(UncaughtExceptionHandler ueh) {
2652 uncaughtExceptionHandler(ueh);
2653 }
2654
2655 void uncaughtExceptionHandler(UncaughtExceptionHandler ueh) {
2656 uncaughtExceptionHandler = ueh;
2657 }
2658
2659 /**
2660 * Dispatch an uncaught exception to the handler. This method is
2661 * called when a thread terminates with an exception.
2662 */
2663 void dispatchUncaughtException(Throwable e) {
2664 getUncaughtExceptionHandler().uncaughtException(this, e);
2665 }
2666
2667 /**
2668 * Holder class for constants.
2669 */
2670 private static class Constants {
2671 // Thread group for virtual threads.
2672 static final ThreadGroup VTHREAD_GROUP;
2673
2674 static {
2675 ThreadGroup root = Thread.currentCarrierThread().getThreadGroup();
2676 for (ThreadGroup p; (p = root.getParent()) != null; ) {
2677 root = p;
2678 }
2679 VTHREAD_GROUP = new ThreadGroup(root, "VirtualThreads", MAX_PRIORITY, false);
2680 }
2681 }
2682
2683 /**
2684 * Returns the special ThreadGroup for virtual threads.
2685 */
2686 static ThreadGroup virtualThreadGroup() {
2687 return Constants.VTHREAD_GROUP;
2688 }
2689
2690 // The following three initially uninitialized fields are exclusively
2691 // managed by class java.util.concurrent.ThreadLocalRandom. These
2692 // fields are used to build the high-performance PRNGs in the
2693 // concurrent code.
2694
2695 /** The current seed for a ThreadLocalRandom */
2696 long threadLocalRandomSeed;
2697
2698 /** Probe hash value; nonzero if threadLocalRandomSeed initialized */
2699 int threadLocalRandomProbe;
2700
2701 /** Secondary seed isolated from public ThreadLocalRandom sequence */
2702 int threadLocalRandomSecondarySeed;
2703
2704 /** The thread container that this thread is in */
2705 private @Stable ThreadContainer container;
2706 ThreadContainer threadContainer() {
2707 return container;
2708 }
2709 void setThreadContainer(ThreadContainer container) {
2710 // assert this.container == null;
2711 this.container = container;
2712 }
2713
2714 /** The top of this stack of stackable scopes owned by this thread */
2715 private volatile StackableScope headStackableScopes;
2716 StackableScope headStackableScopes() {
2717 return headStackableScopes;
2718 }
2719 static void setHeadStackableScope(StackableScope scope) {
2720 currentThread().headStackableScopes = scope;
2721 }
2722
2723 /* Some private helper methods */
2724 private native void setPriority0(int newPriority);
2725 private native void interrupt0();
2726 private static native void clearInterruptEvent();
2727 private native void setNativeName(String name);
2728
2729 // The address of the next thread identifier, see ThreadIdentifiers.
2730 private static native long getNextThreadIdOffset();
2731 }