Condition Mutexes

["Jérôme M. Berger"]

dsimcha wrote:
> == Quote from Bartosz Milewski (bartosz-nospam at relisoft.com)'s article
>> dsimcha Wrote:
>>> void main() {
>>>     condition = new Condition( new Mutex() );
>>>     auto T = new Thread(&waitThenPrint);
>>>     T.start();
>>>     condition.notify();  // Never wakes up and prints FOO.
>>> }
>> Your program terminates immediately after sending the notification. You need to
> stall the exit until the other thread has a chance to wake up.
> 
> Thanks.  I've implemented this, along w/ one other suggestion from another poster.
>  Here's the new program.  It still doesn't work.  Has anyone successfully used
> core.sync.condition from druntime *on D2, not the Tango version on D1*?  If it
> works, then it should be better documented so people who aren't already threading
> gurus can figure out how to use it.  If it doesn't work, then as soon as I can
> confirm that I'm not the problem, I'll go file a bug report.
> 
> Bartosz, since you're a threading guru, could you please write a simple test
> program using core.sync.condition and see if it works, and if not either file a
> bug report or let me know?
> 
> import core.sync.mutex, core.sync.condition, core.thread, std.stdio;
> 
> __gshared Condition condition;
> __gshared Mutex mutex;
> 
> void waitThenPrint() {
>     mutex.lock;
>     condition.wait();
>     mutex.unlock;
>     writeln("FOO");
> }
> 
> void main() {
>     mutex = new Mutex;
>     condition = new Condition(mutex);
>     auto T = new Thread(&waitThenPrint);
>     T.start();
>     condition.notify();  // Never wakes up and prints FOO.
>     T.join;
> }
	Well, you should lock the mutex before calling condition.notify and 
release it afterwards.

	Note that there is always a chance that "notify" will be called 
before the thread starts waiting. In that case your program will 
deadlock (randomly).

		Jerome
-- 
mailto:jeberger at free.fr
http://jeberger.free.fr
Jabber: jeberger at jabber.fr

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