Hello,
>From a general Linux perspective, if you have a knowledge of Linux system
>calls, along with what operations are performed by which web application you
>could use "strace" (use the -f to follow threads). Depending on what you're
>interested in you can filter further for operations on files or network
>activity (i.e. "-e trace=file,network,desc"). If you see a lot of erroneous
>activity (such as constantly trying to open/stat a file that doesn't exist)
>and you know which web app (or Tomcat) is responsible you can address the
>issue.
You could also check "top" to see whether the CPU is being consumed in usr or
sys space, along with whether maybe the memory on your system is maxed out
(trigger high CPU load transfer data between RAM and swap space).
Regards,
Justin Randall
> Date: Tue, 19 Oct 2010 17:40:17 +0200
> From: a...@ice-sa.com
> To: users@tomcat.apache.org
> Subject: what is it doing ?
>
> Hi.
>
> I have a Linux system like so :
>
> Linux arthur 2.6.26-2-686 #1 SMP Mon Aug 30 07:01:57 UTC 2010 i686 GNU/Linux
>
> with a tomcat like so :
>
> Using CATALINA_BASE: /usr/share/tomcat5.5
> Using CATALINA_HOME: /usr/share/tomcat5.5
> Using CATALINA_TMPDIR: /usr/share/tomcat5.5/temp
> Using JRE_HOME: /usr/lib/jvm/java-1.5.0-sun
> Server version: Apache Tomcat/5.5
> Server built: Oct 15 2008 12:57:44
> Server number: 5.5.26.0
> OS Name: Linux
> OS Version: 2.6.26-2-686
> Architecture: i386
> JVM Version: 1.5.0_22-b03
> JVM Vendor: Sun Microsystems Inc.
>
> (Java JDK installed)
>
> and where night and day, tomcat seems to be using a fair amount of CPU time,
> like so :
>
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> 2901 tomcat55 20 0 459m 285m 16m S 13 32.3 354:39.13 java
>
> although by all means, it should not be doing that much sometimes.
>
> How can I figure out what it is actually doing ?
> I mean, which is the easiest standard tool or procedure not requiring a
> degree in quantum
> physics, and which could give me at least a rough idea of which webapp or
> internal tomcat
> process is keeping that CPU busy all the time ?
>
> I have a nagging feeling that someone is going to tell me to take thread
> dumps. If so,
> maybe they would also kindly point out a place where I could find some
> instructions as to
> how to interpret such a thing ?
>
> Thanks
>
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