Question

I have this code in a class:

private static MyObject _locker = new MyObject();

...

lock (_locker)
{
     ...
     _locker = new MyObject();
     ...
}

Will it keep the lock on _locker ?

Answer 1

No, it will not. From the C# specification (emphasis is mine):

A lock statement of the form lock (x)
... where x is an expression of a
reference-type, is precisely
equivalent to

System.Threading.Monitor.Enter(x);
try {
  ...
}
finally {
  System.Threading.Monitor.Exit(x);
}

except that x is only evaluated once.

Since x is not reevaluated the lock will be released.