How do you wait until all threads are finished in Java?

How do I wait for ExecutorService to finish?

Follow one of below approaches.

  1. Iterate through all Future tasks, returned from submit on ExecutorService and check the status with blocking call get() on Future object as suggested by Kiran.
  2. Use invokeAll() on ExecutorService.
  3. CountDownLatch.
  4. ForkJoinPool or Executors.html#newWorkStealingPool.

How do you wait on a thread?

wait() causes current thread to wait until another thread invokes the notify() method or the notifyAll() method for this object. In other words, this method behaves exactly as if it simply performs the call wait(0). The current thread must own this object’s monitor.

What does wait () do in Java?

The wait() method causes the current thread to wait indefinitely until another thread either invokes notify() for this object or notifyAll().

What is the code if main thread should wait until all the other threads are finished in C?

So, if we want that the main thread should wait until all the other threads are finished then there is a function pthread_join(). #include <pthread. h> int pthread_join(pthread_t thread, void **rval_ptr); The function above makes sure that its parent thread does not terminate until it is done.

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Do you need pthread_join?

If you want to be sure that your thread have actually finished, you want to call pthread_join . If you don’t, then terminating your program will terminate all the unfinished thread abruptly. That said, your main can wait a sufficiently long time until it exits.

How can we invoke all waiting threads?

Waiting threads to finish completely in Java

  1. Using join() method of Thread class.
  2. Using CountDownLatch.
  3. Using shutdown(), isTerminated() methods of Executors.
  4. Using invokeAll() method of ExecutorService.
  5. Using invokeAll() method of ExecutorCompletionService.

Should I shutdown ExecutorService?

When finished using an ExecutorService , you need to shut it down explicitly. From its javadoc: “An unused ExecutorService should be shut down to allow reclamation of its resources.” Calling shutdown initiates a gradual and orderly shutdown.

How do I make main thread wait for other threads?

The statement “Thread. currentThread(). join()”, will tell Main thread to wait for this thread(i.e. wait for itself) to die. Thus Main thread wait for itself to die, which is nothing but a deadlock.

Does wait release lock?

Java : Does wait() release lock from synchronized block

The wait function doesn’t release “all locks”, but it does release the lock associated with the object on which wait is invoked.

How do you delay in Java?

The easiest way to delay a java program is by using Thread. sleep() method. The sleep() method is present in the Thread class. It simply pauses the current thread to sleep for a specific time.

Can Notify be called after wait?

Nothing stops you calling notify on an object that’s not being wait ed by another thread. I’d strongly recommend not re-inventing the wheel. Java’s Future interface is designed for results that may only arrive later, and the FutureTask class implements this interface.

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Should I use thread sleep?

One of the way to achieve synchronization, implement wait is by calling Thread. sleep() function however, it is not recommended because this is not very stable and unreliable. The time has to be specified in milliseconds.

Is thread sleep blocking?

sleep is blocking. We now understand that we cannot use Thread. sleep – it blocks the thread. This makes it unusable until it resumes, preventing us from running 2 tasks concurrently.

Is it possible to start a thread twice?

No. After starting a thread, it can never be started again. If you does so, an IllegalThreadStateException is thrown. In such case, thread will run once but for second time, it will throw exception.