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From Yann Ylavic <ylavic....@gmail.com>
Subject Re: mod_http2 and Frequent wake-ups for mpm_event
Date Mon, 06 Feb 2017 12:42:06 GMT
On Mon, Feb 6, 2017 at 1:29 PM, Ruediger Pluem <rpluem@apache.org> wrote:
>
>
> On 02/06/2017 11:56 AM, Yann Ylavic wrote:
>> Hi Stefan,
>>
>> On Mon, Feb 6, 2017 at 9:57 AM, Stefan Priebe - Profihost AG
>> <s.priebe@profihost.ag> wrote:
>>>
>>> your last patch results in multiple crashes every second:
>>
>> Sorry about that, the changes in mpm_event were incorrect (the mutex
>> was cleared with the pool when recycled, hence its pointer was
>> dangling).
>>
>> New patch attached, this time tested with the httpd framework (where
>> the previous patch segfaulted too).
>>
>> Thanks,
>> Yann.
>>
>
> Hmm, does it make sense performance wise to create the mutex over and over again?
> Or is this planned to be improved once it is known to fix the crash issue?

Yes, I'm thinking of it, but it's not easy because we need a pool to
create the mutex.
Using ptrans makes it cleared on recycle (hence re-created), and using
the parent pool (pconf) requires synchronization.

Possibly we could recycle both the pool (or the allocator) and its
mutex, but ap_push/pop_pool() wouldn't be lockless anymore...

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