Is Thread.sleep() synchronised method ?

[Atul Prabhu]

Hi,

  
class ThreadTest extends Thread {
 
public void run() {
    Thread.sleep(1000);
    // do something
}
 
}
 

I create two thread instances of ThreadTest and call the start method of the thread.

In this case whether the Thread.sleep() is synchronised or not ?
Does the user has to handle the synchronised part ?

Regards
Atul

[Ernest Friedman-Hill]

No, sleep() is not a synchronized method, and has no special synchronization concerns -- other than the fact that calling sleep() while holding the lock of any object may be a bad idea.

[Atul Prabhu]

Hi,

Thanks Ernest Friedman-Hill.

If one wants that the current thread to sleep() what should be done without acquiring the lock on the shared object ?

would a call to function which just iterates the "for" loop be sufficient ?
i.e for(int i =0 ; i <1000; i++) {}

or is there anything else which I am not aware of.

Regards
Atul

[Peter Chase]

Using loops to implement time delays went out with BASIC. It is a bad idea because the amount of time delay may vary hugely depending on processor power, loading and also on the extent to which compiler and/or hotspot are able to optimise-away redundant code like an empty loop.

Use Thread.sleep() or Thread.wait(). The former does not require you to hold the lock on "this" and indeed you generally should not hold any locks when doing sleep(). The latter does require you to hold the lock on "this", but releases it while wait()ing, then regains it when finished waiting.

[Vlado Zajac]

Originally posted by Peter Chase:


Use Thread.sleep() or Thread.wait(). The former does not require you to hold the lock on "this" and indeed you generally should not hold any locks when doing sleep(). The latter does require you to hold the lock on "this", but releases it while wait()ing, then regains it when finished waiting.

wait() a an instance method of Object (not only Thread). ("this" is the object used to call wait().)