Re: FastCGI + PHP + APC on Apache2 - Concurrency issues

You were absolutely right, using ab or a bunch of lynxs in different
terminals worked as expected. I am not sure how to have firefox using
different connections for a same site in different tabs, even turning off
keepalive didn't help, but that's another story :)

Thanks!

Renaud

On Mar 17 octobre 2006 17:48, Ben Chabot a écrit :
> Try "ab" Apache Benchmark.
>
> Example :
>
> --- test.php ---
>
> <?
> print date("Y-m-d H:i:s"); print "<br />";
> sleep(5);
> print date("Y-m-d H:i:s"); print "<br />";
> ?>
> --- END test.php ---
>
> --- ab ---
>
> # ab -n 3 -c 3 http://www.host.net/test.php
> This is ApacheBench, Version 2.0.40-dev <$Revision: 1.116 $> apache-2.0
> Copyright (c) 1996 Adam Twiss, Zeus Technology Ltd,
> http://www.zeustech.net/
> Copyright (c) 1998-2002 The Apache Software Foundation,
> http://www.apache.org/
>
> Benchmarking www.host.net (be patient).....done
>
>
> Server Software:        Apache
> Server Hostname:        www.host.net
> Server Port:            80
>
> Document Path:          /test.php
> Document Length:        50 bytes
>
> Concurrency Level:      3
> Time taken for tests:   5.17623 seconds  <-- total time for the test.
> Complete requests:      3
> Failed requests:        0
> Write errors:           0
> Total transferred:      618 bytes
> HTML transferred:       150 bytes
> Requests per second:    0.60 [#/sec] (mean)
> Time per request:       5017.623 [ms] (mean)
> Time per request:       1672.541 [ms] (mean, across all concurrent
> requests)
> Transfer rate:          0.00 [Kbytes/sec] received
>
> --- END ab ---
>
> ab -n 3 -c 3 should mean send 3 requests, 3 concurrently.  The time taken
> for all 3 was 5 seconds, not 15.
>
> If you use livehttpdheaders (firefox extension) and watch what your
> browser
> is sending,  then telnet to your http port and send the same things,
> you'll
> see it isn't like "open connection -> request page -> get result -> end"
>
> It actually keeps the session open to remove the overhead of reconnecting
> for every image and every little things, so it's "open connection ->
> request page -> (wait 10 secs) get result -> ... wait for next request".
>
> So really, it's a combination of things.  Your browser is using the same
> connection to the same apache child, which won't accept the next request
> until it has finished processing the first.
>
> But FastCGI is dealing with the requests in a round robin fashion I
> expect.
>  If you strace  one of them during your refreshes in your browser, you
> will
> probably see it hit one of them only once.  Even though the connection
> stays with the same apache child.  The child sends the request to the
> fastcgi process manager, which does not care which running php process
> processes the request.
>
> So basically, although it seems like it's lagging, it's only lagging for
> that single person who is trying to load a page 3 times in a row that
> takes
> 10 seconds to load. =)
>
> Anyone : feel free to correct me if I am incorrect.
>
> Hope that helps!
> Ben
>
> On 11:05:55 am 10/17/06 "Renaud Drousies" <[email protected]> wrote:
>> Actually I am requesting the page 3 times in 3 different browser tabs
>>
>> On Mar 17 octobre 2006 16:36, Ben Chabot a écrit :
>> >  What method are you using to execute the script three times?
>> >
>> >  Because, afaik, an apache child can only handle one request at a
>> >  time.  So if it's using the same child (sort of like how
>> >  keepalives work) and sending
>> >  the same request to the same apache child, that would explain it, I
>> >  believe.
>> >
>> >  On 9:36:22 am 10/17/06 "Renaud Drousies" <[email protected]>
>> >>  wrote: Hello,
>> >>
>> >>  I am not sure this is actually a FastCGI, Apache2 or PHP
>> >>  configuration issue, but here is my problem:
>> >>
>> >>  I have the current configuration in my apache2:
>> >>
>> >>  Alias /cgi-bin/ /www/cgi-bin/
>> >>  FastCgiServer /www/cgi-bin/php-fcgi -processes 1 -idle-timeout 180
>> >>  -socket /tmp/fastcgi.socket
>> >>  AddType application/x-httpd-fastphp .php
>> >>  Action application/x-httpd-fastphp /cgi-bin/php-fcgi
>> >>
>> >>  And that wrapper:
>> >>
>> >>  #!/bin/sh
>> >>  PHP_FCGI_CHILDREN=4
>> >>  export PHP_FCGI_CHILDREN
>> >>  PHP_FCGI_MAX_REQUESTS=500
>> >>  export PHP_FCGI_MAX_REQUESTS
>> >>  exec /usr/local/bin/php
>> >>
>> >>
>> >>  When I start apache, this gives me the correct number of
>> >> processes:
>> >>  www-data  3422  3421  0 04:59 ?        00:00:00  \_
>> >>  /usr/sbin/fcgi-pm -k start -DSSL
>> >>  www-data  3423  3422  0 04:59 ?        00:00:00  |   \_
>> >>  /usr/local/bin/php www-data  3424  3423  0 04:59 ?
>> >>  00:00:00  | \_ /usr/local/bin/php
>> >>  www-data  3425  3423  0 04:59 ?        00:00:00  |       \_
>> >>  /usr/local/bin/php
>> >>  www-data  3426  3423  0 04:59 ?        00:00:00  |       \_
>> >>  /usr/local/bin/php
>> >>  www-data  3427  3423  0 04:59 ?        00:00:00  |       \_
>> >>  /usr/local/bin/php
>> >>  www-data  3428  3421  0 04:59 ?        00:00:00  \_
>> >>  /usr/sbin/apache2 -k start -DSSL
>> >>  www-data  3429  3421  0 04:59 ?        00:00:00  \_
>> >>  /usr/sbin/apache2 -k start -DSSL
>> >>  www-data  3430  3421  0 04:59 ?        00:00:00  \_
>> >>  /usr/sbin/apache2 -k start -DSSL
>> >>  www-data  3431  3421  0 04:59 ?        00:00:00  \_
>> >>  /usr/sbin/apache2 -k start -DSSL
>> >>  www-data  3432  3421  0 04:59 ?        00:00:00  \_
>> >>  /usr/sbin/apache2 -k start -DSSL
>> >>  www-data  3434  3421  0 04:59 ?        00:00:00  \_
>> >>  /usr/sbin/apache2 -k start -DSSL
>> >>
>> >>
>> >>  I am using only 1 FastCgiServer process because it is required to
>> >>  benefit from the APC cache between the different php handlers. The
>> >>  problem is that I cannot seem to handle more than 1 php request
>> >>  at a time.
>> >>
>> >>  This is a script I am using to test that:
>> >>
>> >>  print date("Y-m-d H:i:s"); print "<br />";
>> >>  sleep(10);
>> >>  print date("Y-m-d H:i:s"); print "<br />";
>> >>
>> >>  If I request that script 3 times, within the same second, it
>> >>  returns me:
>> >>
>> >>  2006-10-17 05:02:35
>> >>  2006-10-17 05:02:45
>> >>
>> >>  2006-10-17 05:02:45
>> >>  2006-10-17 05:02:55
>> >>
>> >>  2006-10-17 05:02:55
>> >>  2006-10-17 05:03:05
>> >>
>> >>  It waits for the previous script to be done to start the next
>> >>  request. Am I doing something wrong in my configuration? I would
>> >>  expect my server to be able to handle more thant 1 request at a
>> >>  time :-)
>> >>
>> >>  Actually this acts the same if I increase the FastCgiServer's
>> >>  -process...
>> >>
>> >>  Thanks!
>> >>
>> >>  Regards,
>> >>  Renaud
>> >>
>> >>
>> >>
>> >>  ___________________________________
>> >>  fastcgi-developers mailing list
>> >>  http://fastcgi.com/fastcgi-developers/
>> >
>> >  ___________________________________
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>> >  http://fastcgi.com/fastcgi-developers/
>> >
>>
>>
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