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From Stefan Priebe - Profihost AG <>
Subject Re: mod_http2 and Frequent wake-ups for mpm_event
Date Mon, 23 Jan 2017 10:48:32 GMT
Am 22.01.2017 um 22:22 schrieb Yann Ylavic:
> Hi Stefan,
> On Sun, Jan 22, 2017 at 8:00 PM, Stefan Priebe - Profihost AG
> <> wrote:
>> Am 22.01.2017 um 18:02 schrieb Eric Covener:
>>> On Sun, Jan 22, 2017 at 11:21 AM, Stefan Priebe - Profihost AG
>>> <> wrote:
>>>> Hi Stefan,
>>>> no i was mistaken customer isn't using mod_proxy - but I think this is
>>>> the patch causing me problems:
>>>> What do you think?
>>> If that is the culprit, you could likely minimize it & help confirm with
>>> * Increase MaxSpareTheads to the current value of MaxClients (aka
>>> MaxRequestWorkers)
>>> * Make sure MaxRequestsPerChild is 0.
>> Why not just revert that one?
> This commit is likely not the "culprit", but probably the one that
> brings up the issue.
> It makes so that mpm event's threads/keepalive connections get
> terminated more agressively/quickly on graceful restart, for the new
> generation of children processes to be able to handle new connections
> also more quickly.
> I agree with Eric that the next test would be to avoid "maintenance"
> graceful restarts by tunning MaxSpareTheads and MaxRequestsPerChild as
> suggested, mod_http2 should then expect the same behaviour from the
> mpm as with 2.4.23.
> You may still reproduce the crash with "explicit" graceful restarts
> (e.g. "apache[2]ctl -k graceful" or "/etc/init.d/apache2 reload"), but
> if it proves to be stable otherwise the issue is still about double
> cleanup/close when http2 pools/buckets are in place.

Thanks for this great explanation this makes sense. Currently i'm
waiting for a next crash. But didn't get one...

no idea which kind of clients are able todo them - but they were very
rare. 99% of the crashes are gone with mod_http2 v1.8.9.

May be i should retest your V7 patch?


> @icing: Any special expectation in mod_h2 with regard to mpm workers
> threads' lifetime (or keepalive connections that should stay alive for
> the configured limit)?
> I see that beam buckets make use of thread local storage/keys for
> locking, and that they also handle the double cleanup like eoc buckets
> did before 1.8.9, but can't follow all the paths yet.
> Maybe something to look at there?

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