Re: Interrupted system call: Failed to acquire SSL session cache lock (Apache Users)

On Wed, Jul 16, 2014 at 7:20 AM, Yann Ylavic <ylavic.dev@xxxxxxxxx> wrote:

On Wed, Jul 16, 2014 at 12:49 PM, Jeff Trawick <trawick@xxxxxxxxx> wrote:
> On Jul 15, 2014 8:46 PM, "Tomlinson, Stuart" <st024y@xxxxxxxxxxxx> 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.

I won't disagree with you at all Yann, but in the interest of promoting the idea that you don't actually have to use all the configuration httpd offers:

If the poster had not made a change from the default based on some developer's silly comment in the documentation, they wouldn't have encountered a problem. It is best to leave the mutex type alone unless you have a specific issue.

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