Hello all,

please consider the following two implementations of class foo. I want to make sure that method bar() is not called simultaneously by two threads, because it does some modification on a member.

Approach 1)

			

			class foo {
			

			private Entity myEntity;
			

			public synchronized bar() {
			

			myEntity.modifiy();
			

			}
			

			}
			

		

Approach 2)

			

			class foo {
			

			private Entity myEntity;
			

			public bar() {
			

			synchronized(this) {
			

			myEntity.modify();
			

			}
			

			}
			

			}
			

		

I know that I can do that with approach 1) and it works fine. Now, I just wanted to try out another way in approach 2). I actually expected that the second approach would also be a possible solution, since the first thread that enters the synchronized block acquires the lock on the instance of foo and a second thread has to wait until the first thread leaves the critical section. But it does not work: multiple threads are entering the critical section simultaneously this way. (In my process, there is only one instance of foo, by the way.)

Thanks for any hints.