We have noticed some "strange" behavior when stress-testing one of our perl modules and we haven't managed to find an explanation or workaround in the mod_perl documentation. We have reproduced this problem with a minimal module, installed as a PerlResponseHandler, that simply sends am HTTP 302 redirection message to the client. The server is a [EMAIL PROTECTED] 512MB, running linux 2.4.18-3, Apache 2.0.48, and mod_perl 1.99_08. We have run benchmarks using the `siege' application with an increasing number of clients and we have measured the latency of every request.
I have put a graph online at http://www.eurecom.fr/~felber/mod_perl.gif that illustrates the problem. The response time of the server is roughly constant but we observe some pretty high spikes in the latency every 30 seconds or so, as if the server was interrupted for a short period of time (approx. 300 ms). The delay of 300 ms seems very high for tasks like shared memory accesses or garbage collection, given that our test module does almost nothing. When running the same test using mod_alias for redirections, there are no such spikes; so it really looks like they are due to mod_perl rather than the OS, Apache, or the network. There might be an obvious explanation but we have limited expertise with mod_perl and we would very much appreciate some help from other users on this list. Thanks, Pascal Felber -- Report problems: http://perl.apache.org/bugs/ Mail list info: http://perl.apache.org/maillist/modperl.html List etiquette: http://perl.apache.org/maillist/email-etiquette.html
