Question

I’m a noob here, and I really need your advice.

I’m working on jBoss/Struts environment, and faced a trouble.
One day I simply replaced cos.jar file in .war/WEB-INF/lib directory with the recent one.
I don’t remember whether the WAS was down or not at that time.

Symptom:
Page loading speed got extremely slow. Sometimes randomly as fast as before, but usually unacceptibly slow. So I monitored WAS’ log then found that connection between WAS and DB is just OK.
Seems that the bottleneck is at the entry point(servlet) or output-related part.

When I do netstat -ano | grep 80, the list shows a lot of CLOSE_WAIT s in keepalive states.

More seriously, it seems like the entire server hangs up for a moment, disconnecting ftp or telnet.

There was no lack of memory or hard disk storage.
Someone suggested me that too large apache log file can cause such problem (not yet tried)

Environment:
Centos 5.4 / Apache / jBoss 5.1GA / cos.jar (1.1 -> 1.4 -> 1.1)

I would greatly appreciate you if you help me.
Thanks for reading.

Answer 1

When you replace a jar file in WEB-INF/lib of an Web Wpplication, the server has to do either one of these things:

• Restart the web application
• Reconstruct the class loader

I would say most of the servers will be restarting the web application because the jar might contain a modified Servlet which has to be reloaded.

Note: The above statement will apply only if Hot Deployment is enabled.