About "when a thread terminates, its own notifyAll method is called" in the Art of Java concurrent programming? How can you see that?

when it comes to Thread.join () in the Art of Java concurrent programming, it says that its implementation depends on wait/notifyAll "s waiting notification mechanism, specifically: when a thread terminates, it calls its own notifyAll method? How can you see that? Check the source code without trace.

what do you think.

Sep.03,2021

the notifyAll () method is called when the Thread is finished, but not in the Java source code, but in the native code of jdk .

openjdk 7 in the source code:

/ jdk7/hotspot/src/os/linux/vm/os_linux.cpp

int ret = pthread_create(&tid, &attr, (void* (*)(void*)) java_start, thread);

static void *java_start(Thread *thread) {
  ...
  thread->run();
  return 0;
}
thread in the

parameter is actually an instance of JavaThread , while in the internal implementation of JavaThread , lock.notify_all (thread) is called before the end of the run method execution to notify all join waiting threads. The source code is as follows:

/ jdk7/hotspot/src/share/vm/runtime/thread.cpp

void JavaThread::run() {
  ...
  thread_main_inner();
}

void JavaThread::thread_main_inner() {
  ...
  this->exit(false);
  delete this;
}

void JavaThread::exit(bool destroy_vm, ExitType exit_type) {
  ...
  // Notify waiters on thread object. This has to be done after exit() is called
  // on the thread (if the thread is the last thread in a daemon ThreadGroup the
  // group should have the destroyed bit set before waiters are notified).
  ensure_join(this);
  ...
}

static void ensure_join(JavaThread* thread) {
  // We do not need to grap the Threads_lock, since we are operating on ourself.
  Handle threadObj(thread, thread->threadObj());
  assert(threadObj.not_null(), "java thread object must exist");
  ObjectLocker lock(threadObj, thread);
  // Ignore pending exception (ThreadDeath), since we are exiting anyway
  thread->clear_pending_exception();
  // Thread is exiting. So set thread_status field in  java.lang.Thread class to TERMINATED.
  java_lang_Thread::set_thread_status(threadObj(), java_lang_Thread::TERMINATED);
  // Clear the native thread instance - this makes isAlive return false and allows the join()
  // to complete once we've done the notify_all below
  java_lang_Thread::set_thread(threadObj(), NULL);
  lock.notify_all(thread);
  // Ignore pending exception (ThreadDeath), since we are exiting anyway
  thread->clear_pending_exception();
}
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MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1bdd87c-31363.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1bdd87c-31363.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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