上邊已經回答你的問題，線程結束時會呼叫notifyAll。

JVM底層實際上是使用OS層提供的API來支援線程的，例如UNIX-Like的OS中一般使用pthread(Windows也有Pthread的實作），openjdk的hotspotVM使用的就是pthread，我們來看看openjdk8版本的hotspotVM底層實際代碼。

在Thread執行start的方法時，就會呼叫native方法的start0，start0底層實際經過很多層的封裝，最終會呼叫createJavaThread的方法，createJavaThread就會調pthread_create建立一個執行緒並執行。

過程大致是這樣的：Thread.start() -> start0() -> ... -> createJavaCreate() -> pthread_create() => threadStart() => attachThread() -> 執行Thread的run() -> detachThread() "這個方法最後會呼叫Object.notifyAll"。

openjdk-8-8u66-b17/jamvm-2.0.0/src/thread.c

void createJavaThread(Object *jThread, long long stack_size) {
    Thread *self = threadSelf();
    ExecEnv *ee = sysMalloc(sizeof(ExecEnv));
    Thread *thread = sysMalloc(sizeof(Thread));

    memset(ee, 0, sizeof(ExecEnv));
    memset(thread, 0, sizeof(Thread));

    thread->ee = ee;
    ee->thread = jThread;
    ee->stack_size = stack_size;

    if(!classlibCreateJavaThread(thread, jThread)) {
        sysFree(thread);
        sysFree(ee);
    return;
    }

    disableSuspend(self);

    if(pthread_create(&thread->tid, &attributes, threadStart, thread)) {
        classlibMarkThreadTerminated(jThread);
        sysFree(ee);
    enableSuspend(self);
        signalException(java_lang_OutOfMemoryError, "can't create thread");
        return;
    }

    pthread_mutex_lock(&lock);

    /* Wait for thread to start */
    while(classlibGetThreadState(thread) == CREATING)
        pthread_cond_wait(&cv, &lock);

    pthread_mutex_unlock(&lock);
    enableSuspend(self);
}

....

void *threadStart(void *arg) {
    Thread *thread = (Thread *)arg;
    Object *jThread = thread->ee->thread;

    /* Parent thread created thread with suspension disabled.                                                                                                                                 
       This is inherited so we need to enable */
    enableSuspend(thread);

    /* Complete initialisation of the thread structure, create the thread                                                                                                                     
       stack and add the thread to the thread list */
    initThread(thread, INST_DATA(jThread, int, daemon_offset), &thread);

    /* Add thread to thread ID map hash table. */
    addThreadToHash(thread);

    /* Set state to running and notify creating thread */
    signalThreadRunning(thread);

    /* Execute the thread's run method */
    executeMethod(jThread, CLASS_CB(jThread->class)->method_table[run_mtbl_idx]);

    /* Run has completed.  Detach the thread from the VM and exit */
    detachThread(thread);

    TRACE("Thread %p id: %d exited\n", thread, thread->id);
    return NULL;
}

void *detachThread(Thread *thread) {
    Object *keep_alive;
    ExecEnv *ee = thread->ee;
    Object *java_thread = ee->thread;
    Object *group = INST_DATA(java_thread, Object*, group_offset);

    /* If there's an exception pending, it is uncaught */
    if(exceptionOccurred0(ee))
        uncaughtException();

    /* Don't do anything if this is the main thread */
    if(thread->prev == NULL)
        return NULL;

    /* remove thread from thread group */
    executeMethod(group, (CLASS_CB(group->class))->
                              method_table[rmveThrd_mtbl_idx], java_thread);

    /* Remove thread from the ID map hash table */
    deleteThreadFromHash(thread);

    objectLock(java_thread);

    /* Mark the thread as terminated.  This state is used in determining                                                                                                                      
       if the thread is alive and so must be done before notifying joining                                                                                                                    
       threads.  The VM thread structure is tied to a Java-level object                                                                                                                       
       (see comment below).  The keep_alive is an object which must be                                                                                                                        
       kept alive to prevent the structure from being freed while we are                                                                                                                      
       still accessing it */
    keep_alive = classlibMarkThreadTerminated(java_thread);

    /* Notify any threads waiting on the thread object -                                                                                                                                      
        these are joining this thread 这里调用objectNotifyAll */
    objectNotifyAll(java_thread);

    objectUnlock(java_thread);

    /* Thread's about to die, so no need to enable suspend                                                                                                                                    
       afterwards. */
    disableSuspend(thread);

    /* Grab global lock, and update thread structures protected by                                                                                                                            
       it (thread list, thread ID and number of daemon threads) */
    pthread_mutex_lock(&lock);
 /* It is safe to free the thread's ExecEnv and stack now as these are                                                                                                                     
       only used within the thread.  It is _not_ safe to free the native                                                                                                                      
       thread structure as another thread may be concurrently accessing it.                                                                                                                   
       However, they must have a reference to the java level thread --                                                                                                                        
       therefore, it is safe to free during GC when the thread is determined                                                                                                                  
       to be no longer reachable. */
    sysFree(ee->stack);
    sysFree(ee);

    /* If no more daemon threads notify the main thread (which                                                                                                                                
       may be waiting to exit VM).  Note, this is not protected                                                                                                                               
       by lock, but main thread checks again */

    if(non_daemon_thrds == 0) {
        /* No need to bother with disabling suspension                                                                                                                                        
           around lock, as we're no longer on thread list */
        pthread_mutex_lock(&exit_lock);
        pthread_cond_signal(&exit_cv);
        pthread_mutex_unlock(&exit_lock);
    }

    /* Finally, clear the thread local data */
    setThreadSelf(NULL);

    TRACE("Thread %p id: %d detached from VM\n", thread, thread->id);
    return keep_alive;
}

....

你的推斷應該是對的,線程死的時候會調用自己的notifyAll方法
As a thread terminates the this.notifyAll method is invoked. It is recommended that applications not use wait, notify, or notifyAll on Thread instances.
java/lang/Thread.java#1258