[Info-vax] Apache + mod_php performance

[Arne Vajhøj]

On 9/27/2024 8:38 PM, Dan Cross wrote:
> In article <vd7hbi$tgu3$2 at dont-email.me>,
> Arne Vajhøj  <arne at vajhoej.dk> wrote:
>> On 9/25/2024 5:10 PM, Arne Vajhøj wrote:
>>> It must be Apache.
>>>
>>> Apache on VMS is prefork MPM. Yuck.
>>>
>>> MaxSpareServers 10 -> 50
>>> MaxClients 150 -> 300
>>>
>>> actually did improve performance - double from 11 to 22
>>> req/sec.
>>>
>>> But the system did not like further increases. And besides
>>> these numbers are absurd high to handle a simulator doing requests
>>> from just 20 threads.
>>>
>>> But not sure what else I can change.
>>
>> And we have a solution.
>>
>> httpd.conf
>>
>> KeepAlive On
>> ->
>> KeepAlive Off
>>
>> And numbers improve dramatically.
> 
> Hmm. You had already said that you were _Not_ using keep alives
> because that would somehow mimic multiple machines querying
> simultaneously.

That is correct.

The client was not using keep alive.

But the server was configured to support keep alive.

Turning that capability off on the server solved the performance
problem.

No changes on client.

No keep alive used before - no keep alive used after.

Just disabling the capability on the server.

> This was, of course, the area of investigation I had suggested
> to you previously to try and nail down the baseline.  I question
> whether this will impact your single query latency, however, or
> whether this is masking it in your benchmark.
> 
>> nop.txt 281 req/sec
>> nop.php 176 req/sec
>> real PHP no db con pool 94 req/sec
>> real PHP db con pool 103 req/sec
>>
>> Numbers are not great, but within acceptable.
> 
> What is your single query latency?  Not calculated, but
> actually measured.

It is a rather uninteresting number.

But easy to test. It obviously vary a bit, but they
are all in the 50-100 millisecond range.

>> It is a bug in the code.
> 
> The evidence in hand is insufficient to make that claim.

I believe that server config supporting keep alive
causing performance to drop to 1/10'th for clients
not using keep alive is a bug.

Arne