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From Yann Ylavic <ylavic....@gmail.com>
Subject Re: [users@httpd] Interrupted system call: Failed to acquire SSL session cache lock
Date Wed, 16 Jul 2014 11:20:37 GMT
On Wed, Jul 16, 2014 at 12:49 PM, Jeff Trawick <trawick@gmail.com> wrote:
> On Jul 15, 2014 8:46 PM, "Tomlinson, Stuart" <st024y@intl.att.com> wrote:
>>
>> Are there any expected negative impacts from using "sysvsem" instead of
>> "sem" (which I understand defaults to "posixsem" - described in the
>> documentation as "elegant", whereas "sysvsem" is merely "somewhat elegant")?
>
> Funny developers...
>
> There is safety in numbers (i.e., use what other people on your platform
> use, unless you have a specific problem).  sysvsem is the default on Linux.
> (I assume you are using Linux, but maybe that is not the case.)
>
> Using sysvsem on Solaris with the prefork MPM, you would likely have to
> increase the number of semaphore undo structures (at least in the old days;
> I can't find my normal go-to reference for AcceptMutex oddities; Eric?)

SSLMutex/AcceptMutex "pthread" work very well on Linux, and have the
advantage to be "robust" against children crashing while holding the
lock (like sysvsem, unlike posixsem AFAICT), without system limits
(unlike sysvsem).

This is probably true for all unixes that HAVE_PTHREAD_MUTEX_ROBUST
(ie. pthread_mutexattr_setrobust_np), but I can't verify that.

Regards,
Yann.

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