CODEWITHSUNDEEP
javamultithreading
dibugger
dibugger

Reputation: 576

Stop a thread and release the lock in Java

I have a ServerState object:

public class ServerState {
    public static final LOCK = new ReentrantLock();
    public static Map<String, Object> states = new HashMap<>();
}

Thread A:

public class ThreadA extends Thread {
    @Override
    public void run() {
        ServerState.LOCK.lock();
        // do some dirty work
        ServerState.LOCK.unlock();
    }
}

My question is: when thread A has acquired the lock and is doing some dirty work, thread B wants to terminate A immediately but want it release the lock before its terminate, how can I achieve this? I am not looking for use a flag to indicate whether the thread is terminated like this:

public class ThreadA extends Thread {
    volatile boolean isFinished = false;
    @Override
    public void run() {
        while (!isFinished) {
            ServerState.LOCK.lock();
            // do some dirty work
            ServerState.LOCK.unlock();
        }
}

What I want to achieve is to terminate the thread and release the lock WITHOUT proceeding to the next iteration. Is is possible to do it in Java?

Upvotes: 0

Views: 1578

Answers (1)

Kirill
Kirill

Reputation: 8341

You can use thread interruption mechanism. If you want to interrupt on LOCK acquiring, you should use LOCK.lockInterruptibly() instead of LOCK.lock():

Thread thread1 = new Thread() {
  @Override
  void run() {
    try {
      LOCK.lockInterruptibly();
      System.out.println("work");
      LOCK.unlock();
    } catch (InterruptedException ier) {
      this.interrupt()
    }
  }
};

Then, to stop thread1 just call

thread1.interrupt();

from another thread.

Also I'd suggest to move actual logic from Thread to Runnable:

Thread thread1 = new Thread(
  new Runnable() {
    @Override
    void run() {
      try {
        LOCK.lockInterruptibly();
        System.out.println("work");
        LOCK.unlock();
      } catch (InterruptedException ier) {
        Thread.currentThread().interrupt()
      }
    }
  }
);

Upvotes: 1

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