What tools are available for managing thread or task synchronization in parallel programming?

In Java, various tools are used for thread synchronization and task management:

• The synchronized keyword — blocks access to code or objects so that only one thread can execute that section of code at a time.

• Lock objects from java.util.concurrent.locks — a more flexible alternative to synchronized, for example, ReentrantLock allows explicit locking and unlocking.

• Classes from the java.util.concurrent package:

  • Semaphore — limits the number of threads that can access a resource simultaneously.
  • CountDownLatch — allows one or more threads to wait until other threads complete certain actions.
  • CyclicBarrier — synchronizes groups of threads, making them wait for each other.
  • Exchanger — enables two threads to exchange data.

• Volatile variables — ensure visibility of variable changes between threads without locks.

• Atomic classes (AtomicInteger, AtomicReference, etc.) — provide atomic operations without using locks.

Example of using synchronized:

public class Counter {
    private int count = 0;

    public synchronized void increment() {
        count++;
    }

    public synchronized int getCount() {
        return count;
    }
}