sandychops

 Profile Answers by sandychops 

• Feb 24th, 2015

 

Lock is a thread synchronization mechanism similar to synchronized blocks. From Java 5 the package java.util.concurrent.locks contains several lock implementations which we can use to achieve synchronization.

For example: to synchronize a block of code like

Code
public int increment(){


    synchronized(this){


      return ++count;


    }


  }

Here count++ could lead to Read-modify-write concurrency problem where one thread is updating where as another thread is reading and this could lead to lost update or incorrect read.
So to achieve synchronized we can use the synchronize(this) or implement locks as below

Code
private Lock lock = new Lock();


  private int count = 0;


 


  public int increment(){


    lock.lock();


    int newCount = ++count;


    lock.unlock();


    return newCount;


  }

Vishal

• Jan 1st, 2018

 

When we are working with multiple threads, we have to make sure multiple threads are working on synchronized object otherwise different threads might see different values for same variables.
In order to do that we have synchronization which gives a lock to a particular thread and when this thread releases the lock next thread takes the lock and execute itself.