Re: Pthread-win32 races?

[Ross Johnson <Ross.Johnson@homemail.com.au>]

Sergey Fokin wrote:
> Hello.
>
>> The library is working correctly since sem_destroy() is returning the
>> error EBUSY as required and documented at:
>>
>> http://sourceware.org/pthreads-win32/manual/sem_init.html
>>
>> This is also in accordance with the Single Unix Specification. If it was
>> hanging your program rather than returning the error then that would be
>> a problem.
>
> The sem_destroy function sets errno to the following error code on error:
> EBUSY if some threads are currently blocked waiting on the semaphore.
>
> But there's obviously no threads waiting on semaphore, is there?
My apologies - I didn't even see the sem_wait() even though it's right 
before the sem_destroy(), and regardless, as you say, it should only 
return EBUSY if someone is waiting, not posting. It's been a while but 
the code looks like it tries to ensure this. I'll have to look closer 
when I'm more awake.
>
>> By the way, in your sample code you don't check the return code from the
>> sem_post(), but the semaphore could already be destroyed at that point.
>
> It couldn't (shouldn't, because actually it does). Because semaphore
> is destroyed only after sem_wait(), but sem_wait() returns (should
> return) only after sem_post() succeeds. Did I understood right?
As above - my mistake.

Ross