C# Monitor class

The

lock statement is parsed by the C# compiler to use the Monitor class.The following lock statement:

lock(obj){  // ​​synchronized region for obj}

is resolved to call the Enter() method, which waits until the thread locks the object.Only one thread can lock an object at a time, as long as the lock is released.The thread can then enter the synchronization phase.The Exit() method of the Monitor class releases the lock.The compiler puts the Exit() method in the finally handler of the try block, so if an exception is thrown, the lock is released.​​​​​​​​

Monitor.Enter(obj);try{  // ​​synchronized region for obj}finally{ Monitor.Exit(obj);}

The main advantage of the Monitor class over C#'s lock statement is that you can add a timeout value for waiting to be locked.This way, instead of waiting indefinitely to be locked, the TryEnter() method can be used as in the example below, passing it a timeout value specifying the maximum time to wait to be locked.If obj is locked, the TryEnter() method sets the Boolean reference parameter to true and synchronously accesses the state locked by the object obj.If another thread locks obj for more than 500 milliseconds, the TryEnter() method sets the variable lockTaken to false, and the thread no longer waits, but is used to perform other operations.Maybe later, the thread will try to acquire the lock again.​​​​​​​​

bool _lockTaken = false;Monitor.TryEnter(_obj, 500, ref _lockTaken); if (_lockTaken)  { try  { // acquired the lock // synchronized region for obj   } finallycode> {   Monitor.Exit(obj);  }}else{ // didn't get the lock, do something else}