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From Eric Covener <cove...@gmail.com>
Subject Re: [users@httpd] problems benchmarking php-fpm/proxy_fcgi with h2load
Date Mon, 05 Feb 2018 01:41:32 GMT
On Sun, Feb 4, 2018 at 8:27 PM, Luca Toscano <toscano.luca@gmail.com> wrote:
> Hi Hajo,
>
>
> 2018-02-01 3:58 GMT+01:00 Luca Toscano <toscano.luca@gmail.com>:
>>
>> Hi Hajo,
>>
>> 2018-01-31 2:37 GMT-08:00 Hajo Locke <Hajo.Locke@gmx.de>:
>>>
>>> Hello,
>>>
>>>
>>> Am 22.01.2018 um 11:54 schrieb Hajo Locke:
>>>
>>> Hello,
>>>
>>> Am 19.01.2018 um 15:48 schrieb Luca Toscano:
>>>
>>> Hi Hajo,
>>>
>>> 2018-01-19 13:23 GMT+01:00 Hajo Locke <Hajo.Locke@gmx.de>:
>>>>
>>>> Hello,
>>>>
>>>> thanks Daniel and Stefan. This is a good point.
>>>> I did the test with a static file and this test was successfully done
>>>> within only a few seconds.
>>>>
>>>> finished in 20.06s, 4984.80 req/s, 1.27GB/s
>>>> requests: 100000 total, 100000 started, 100000 done, 100000 succeeded, 0
>>>> failed, 0 errored, 0 timeout
>>>>
>>>> so problem seems to be not h2load and basic apache. may be i should look
>>>> deeper into proxy_fcgi configuration.
>>>> php-fpm configuration is unchanged and was successfully used with
>>>> classical fastcgi-benchmark, so i think i have to doublecheck the proxy.
>>>>
>>>> now i did this change in proxy:
>>>>
>>>> from
>>>> enablereuse=on
>>>> to
>>>> enablereuse=off
>>>>
>>>> this change leads to a working h2load testrun:
>>>> finished in 51.74s, 1932.87 req/s, 216.05MB/s
>>>> requests: 100000 total, 100000 started, 100000 done, 100000 succeeded, 0
>>>> failed, 0 errored, 0 timeout
>>>>
>>>> iam surprised by that. i expected a higher performance when reusing
>>>> backend connections rather then creating new ones.
>>>> I did some further tests and changed some other php-fpm/proxy values,
>>>> but once "enablereuse=on" is set, the problem returns.
>>>>
>>>> Should i just run the proxy with enablereuse=off? Or do you have an
>>>> other suspicion?
>>>
>>>
>>>
>>> Before giving up I'd check two things:
>>>
>>> 1) That the same results happen with a regular localhost socket rather
>>> than a unix one.
>>>
>>> I changed my setup to use tcp-sockets in php-fpm and proxy-fcgi.
>>> Currently i see the same behaviour.
>>>
>>> 2) What changes on the php-fpm side. Are there more busy workers when
>>> enablereuse is set to on? I am wondering how php-fpm handles FCGI requests
>>> happening on the same socket, as opposed to assuming that 1 connection == 1
>>> FCGI request.
>>>
>>> If "enablereuse=off" is set i see a lot of running php-workerprocesses
>>> (120-130) and high load. Behaviour is like expected.
>>> When set "enablereuse=on" i can see a big change. number of running
>>> php-workers is really low (~40). The test is running some time and then it
>>> stucks.
>>> I can see that php-fpm processes are still active and waiting for
>>> connections, but proxy_fcgi is not using them nor it is establishing new
>>> connections. loadavg is low and benchmarktest is not able to finalize.
>>>
>>> I did some further tests to solve this issue. I set ttl=1 for this Proxy
>>> and achieved good performance and high number of working childs. But this is
>>> paradoxical.
>>> proxy_fcgi knows about inactive connection to kill it, but not reenable
>>> this connection for working.
>>> May be this is helpful to others.
>>>
>>> May be a kind of communicationproblem and checking health/busy status of
>>> php-processes.
>>> Whole proxy configuration is  this:
>>>
>>> <Proxy "unix:/dev/shm/php70fpm.sock|fcgi://php70fpm">
>>>     ProxySet enablereuse=off flushpackets=On timeout=3600 max=15000
>>> </Proxy>
>>> <FilesMatch \.php$|\.php70$>
>>>    SetHandler "proxy:fcgi://php70fpm"
>>> </FilesMatch>
>>
>>
>> Thanks a lot for following up and reporting these interesting results!
>> Yann opened a thread[1] on dev@ to discuss the issue, let's follow up in
>> there so we don't keep two conversations open.
>>
>> Luca
>>
>> [1]:
>> https://lists.apache.org/thread.html/a9586dab96979bf45550c9714b36c49aa73526183998c5354ca9f1c8@%3Cdev.httpd.apache.org%3E
>>
>
> reporting in here what I think it is happening in your test environment when
> enablereuse is set to on. Recap of your settings:
>
> /etc/apache2/conf.d/limits.conf
> StartServers          10
> MaxClients          500
> MinSpareThreads      450
> MaxSpareThreads      500
> ThreadsPerChild      150
> MaxRequestsPerChild   0
> Serverlimit 500

>
> <Proxy "unix:/dev/shm/php70fpm.sock|fcgi://php70fpm/">
>     ProxySet enablereuse=on flushpackets=On timeout=3600 max=1500
> </Proxy>
> <FilesMatch \.php$|\.php70$>
>    SetHandler "proxy:fcgi://php70fpm/"
> </FilesMatch>
>
> request_terminate_timeout = 7200
> listen = /dev/shm/php70fpm.sock
> pm = ondemand
> pm.max_children = 500
> pm.max_requests = 2000
>
> By default mod_proxy allows a connection pool of ThreadsPerChild connections
> to the backend for each httpd process, meanwhile in your case you have set
> 3200 using the 'max' parameter (as stated in the docs it is a per process
> setting, not a overall one). PHP-FPM handles one connection for each worker
> at the time, and your settings allow a maximum of 500 processes, therefore a
> maximum of 500 connections established at the same time from httpd. When
> connection reuse is set to on, the side effect is that for each mod_proxy's
> open/established connection in the pool there will be one PHP-FPM worker
> tight to it, even if not serving any request (waiting for one basically).

We should definitely spell out the impact of enablereuse on php-fpm
specifically.

I think one thing that is missing in the above recap is that w/o H2
given MaxClients=500, the impact is probably nil because there are
simply not enough server threads to max out the pool and still try to
make new connections.

With H2, you have N additional h2 worker threads per process, so it
puts it as out of balance as if MaxClients were larger but
pm.max_children were not.

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