Hi!



I have a synchronization question:



I have the following code:



int waiting = 0;

object obj = new Object();



public void foo()

{

waiting++;



synchronized (obj)

{

waiting--;



...

}

}



Of course that when many threads try to enter that method, only the
first will succeed and that other will wait at the synchronized block.



My question is that: Suppose threads A, B, C, D, E arrive at this order
and thread A captures the obj Object's monitor at the synchronized block.
Meanwhile thread B is waiting, and so is C, D, E (B came first, and so on).



When A releases the monitor at the end of the synchronized block - to the
waiting threads enter it in a queue manner (i.e. B, then when B is done C,
and so on) - or is it random?



I have tested that over and over
again, because I thought that the order is random, but in every time I saw (with debug prints)
that is had the behaviour of a queue. There
wasn't a single time it went otherwise.



Since it is important for me to have it as a queue, I really need to know whether that is the defined
behaviour or maybe that was just incident.



Can anyone help me?