Hi all,
We use an apache httpd as a forward proxy load balancer, which
forwards requests to one of the two internal Tomcat application
servers. There are some issues with the performance of mod_proxy. We
have enabled logging to time to serve request for both the httpd and
Tomcat servers.
Many a times (in around 10-15% of all requests), time to respond for
the httpd is 5-10 seconds while the Tomcat server was able to serve
the request in less than a second. This means that the httpd is adding
a delay of 5-10 seconds in just fetching the content from Tomcat and
sending it to the client. What could be the reason for this delay.
Some details about our setup:
- We are using a compiled from source apache 2.2 on RHEL 4.
- all our servers are on high-speed internal LAN which is not clogged.
- httpd server is run on a 4-processor AMD machine with 8 GB RAM. CPU
usage never exceeds 100% (of 400% available). Swap usages are zero.
This means, there is no lack of resources.
- The traffic is around 70-80 requests a minute, which consists of
many small static image and js files and some dynamic files from
Tomcat.
- Rewrite rules are used for redirecting the traffic:
ProxyPassReverseCookiePath /appname /
RewriteMap SERVERS rnd:/etc/httpd/conf/balancer.conf
RewriteEngine On
RewriteRule ^/static/(.*) /path/to/static/$1 [L]
RewriteCond "%{HTTP_COOKIE}" "(^|;\s*)JSESSIONID=\w*\.(\w+)($|;)"
RewriteRule "(.*)" "http://${SERVERS:%2}%{REQUEST_URI}"; [P,L]
RewriteRule "^.*;JSESSIONID=\w*\.(\w+)($|;)"
"http://${SERVERS:$1}%{REQUEST_URI}"; [P,L]
RewriteRule "(.*)" "http://${SERVERS:ALL}%{REQUEST_URI}"; [P,L]
Any help will be greatly appreciated.
thanks
Nilesh Bansal.
http://queens.db.toronto.edu/~nilesh/
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