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help regarding synchronized methods

Venu Chakravorty
Ranch Hand

Joined: Aug 19, 2009
Posts: 46
Hi,
I can't understand the output of the following code:


Output (on my machine):
t1: in run
t1: about to sleep
t2: in run
t2: about to sleep
t1: dying
t2: dying


I thought (and still think) the output would be:
t1: in run
t1: about to sleep
t2: in run
t1: dying
t2: about to sleep
t2: dying

How is "t2: about to sleep" printed before "t1: dying"? Isn't "t1" supposed to die before "t2" can get a lock on "synchronized void meth()"?

regards, venu
Miklos Szeles
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Joined: Oct 21, 2008
Posts: 142
Hi venu,

There's no connection between mt1's and mt2's meth method. It's not a static method. synchronized void meth() guarantess only that the meth calls for the given instance will be synchronized.
sujith Acharya
Ranch Hand

Joined: Dec 25, 2006
Posts: 60
synchronized method doesnt allow another thread enter to the method through the same object. In your case t1 and t2 enters the method meth() through different objects mt1 and mt2. So the lock doesnt prevent t2 entering meth() while t1 executing meth() or vice versa.

Venu Chakravorty
Ranch Hand

Joined: Aug 19, 2009
Posts: 46
thanks mates.
 
It is sorta covered in the JavaRanch Style Guide.
 
subject: help regarding synchronized methods