On 25.01.2012 14:18, DENIS Laurent wrote:
Hello, *** Question *** How can I measure how much time is spent in the processing function of module? Of course, the supplier of the module does not provide any source code. My idea is to add an APRLOG_DEBUG the "apr_time_now" before and after the function is called (don't know yet which hook it's registered to, guess I'll have to add debug around all hooks). But I haven't found in which source code file the function is called. Even the faintest hint would greatly help me. *** Context *** On a Sparc T5120 server with (1 CPUs, 64vCPU, 64GB memory), running Solaris 10 + apache 2.2.21 worker / 2.2.17 prefork, I have "intermittent" slow responses. The server is not overloaded (5% CPU, 50GB free memory, 5MB/second on network link). The problem occurs for around 0.5% of the request (ran thousands of request) - even for very simple pages like an index.html of 20 bytes on non-SSL server.
Since it is on Solaris, you could try to use Dtrace.
The delay occurs between the moment the moment the request is received and the moment the first byte of the header is sent to the client (verified with tcpdump on server + perl script with IO::Socket to have a better idea that with a wget). The time shown by the logs (%D) is way above the second (sometimes up to 120 seconds where the average time is 4ms).
%T gives better resolution.
The server is under moderate load: 200 requests / second and have a very complex configuration (lots of forwards, rewrite, aliases, vhosts, etc...) There's an external module loaded for CA Siteminder that performs authentication. I suspect this one to be guilty for the delay, maybe by its communication with the policy server. I cannot isolate the traffic to the policy server for one request, the channel is cyphered and used for all the requests.
And it is not one connection per request?
No "timing" log option available in this module as far as I can find. On a lightly loaded server, the delay does not appear, so I need to test on the production server.
mod_info could tell you about the hoks used by siteminder, so it could be possible to narrow down the cause with a custom module.
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