Re: [Boost-users] [thread] Never enter critical section [NC]

From: Peter Dimov (pdimov_at_[hidden])
Date: 2007-08-30 15:35:30

> Well... let's take the example of an interruptible task. We have a main
> program which launches a thread.
> Now, we want to stop this thread. We can use interruption or the following
> code:
>
> T1:
> while(true)
> {
>        lock lk(mutex);
>        if (end) break;

          lk.unlock();

>        /* dosomething */
> }
>
> T2:
> interruptT1()
> {
>        lock lk(mutex);
>        end = true;
> }

T2 only needs access to 'end', it doesn't touch the shared state modified by 
'dosomething', so it doesn't need to be prevented from running in parallel 
with 'dosomething'. The general rule is to keep the critical regions as 
short as possible and not reuse the same mutex for unrelated tasks.

In this specific case one can also use an atomic variable, of course.