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From Salikh Zakirov <Salikh.Zaki...@Intel.com>
Subject apr_thread_cond_signal() lost?
Date Mon, 15 Jan 2007 09:33:36 GMT
Hi,

I have not get any response.
Assuming that silence was caused by the long vacation, resending in hope
to get some response.

Thanks.

Salikh Zakirov wrote:
> Hi,
>
> the current implementation of apr_thread_cond_signal() on Windows
> has a deficiency: it may lose several concurrent or sequential
> signal() calls if more than one thread is waiting on a condition
> variable, because there is no count of the number of signal() calls,
> and only one woken up thread will really come out of the loop.
>
> As far as I can see, APR condition variables are meant as a portable
> replacement for pthread condition variable, however, the lost signal()
> behaviour is not compliant with pthread_cond_signal() specification [1]:
>
> 	The pthread_cond_signal() function shall unblock at least one of the
> 	threads that are blocked on the specified condition variable cond
> 	(if any threads are blocked on cond).
>
> Unfortunately, neither compliance nor defiance to this requirement is specified
> in APR manual, so I do not know if it is intentional or not.
>
> Can any of APR developers clarify their position?
>
> DRLVM [2] is using APR as its porting layer, however, due to the lost signal()
> issue it is forced to use its own implementation of conditional variables,
> currently arranged as an APR patch [3] (not really a patch, but a couple of
> files replaced).
>
> I am not the original author of the mentioned code, so I cannot submit it
> for inclusion into APR directly, however, the code is available from Apache
> Harmony repository licensed under AL2, and I know and can contact original
> author, though he has low motivation on submitting the patch himself.
>   

I've submitted APR bug 41243 [41243] to track this issue.


> Can this fix be included into APR?
>
> [1] http://www.unix.org/single_unix_specification/, pthread_cond_signal() page
> [2] http://harmony.apache.org/subcomponents/drlvm/index.html
> [3]
> http://svn.apache.org/viewvc/harmony/enhanced/drlvm/trunk/build/patches/win/APR/locks/win32/thread_cond.c?view=markup
> http://svn.apache.org/viewvc/harmony/enhanced/drlvm/trunk/build/patches/win/APR/include/arch/win32/apr_arch_thread_cond.h?view=markup
> [41243] http://issues.apache.org/bugzilla/show_bug.cgi?id=41243

-- 
Salikh Zakirov


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