SatyaCodes

Java- Synchronization VS Locks

Synchronization VS Locks

There are few differences between the use of synchronized block and using Lock API’s

  • A synchronized block is fully contained within a method we can have Lock API’s lock() and unlock() operation in separate methods. 
    public class ThreadDemo extends Thread {
    
	Lock lock = new ReentrantLock();
	public int sum(int a, int b) {
 //Locking in one method
 lock.lock();
 a = 10;
 b = 20;
 return a + b;
	}
	public void show() {
 System.out.println(sum(10, 20));
 //UnLocking in another method
 lock.unlock();
	}
}

  • A synchronized block does not support the fairness, any thread can acquire the lock ones released, no preference can be specified. We can achieve fairness within the Lock APIs by specifying the fairness property. It makes sure that longest waiting thread is given access to lock.

  • A thread gets blocked if it can’t get an access to the synchronized block. The Lock API provides tryLock() method. The thread acquires lock only if it’s available and not held by any other thread. This reduces blocking time of thread waiting for the lock. 
    if(l.tryLock())
{//perform safe operations
}else{
	//perform alternative operations 
}
  • A thread which is in -waiting” for a long time(say hours) to acquire the access to synchronized block, can’t be interrupted. The Lock API provides a method lockInterruptibly() which can be used to interrupt the thread when it is waiting for the lock
Search