Hi, Lindsay, Sorry for my ignorance, but seeing that you were trying to locate the thread using "PID", I think perhaps it's wrong. I have the same experience identifying such a CPU utilization issue on a Debian box using a 2.6.x version kernel. I cannot recall whether on a 2.4.x kernal linux box you can use ps to see "TID", the native thread id. Well, maybe you can refer to http://iusr.spaces.live.com/blog/cns!69F4725ED815E770!408.entry , this is a summary after I resolving the same problem. Hope it can help.
On 9/22/07, Lindsay Patten <[EMAIL PROTECTED]> wrote: > I am looking for information on how to debug a problem. Any pointers to > documentation, suggestions of approaches etc. would be much appreciated. > > I am having a problem with my tomcat server periodically going into a > state where it is using up all the available cpu and providing very slow > response. None of the jsp or servlets on the site should take up a lot > of cpu, they all just do relatively simple database queries and produce > simple html pages from the results. During the times when the cpu is > busy the database will generally not be under any significant load. > > Top shows process 324 (0x144) as the busy process, and ps shows it > having consumed a lot of cpu: > PID TTY STAT TIME COMMAND > 324 ? S 837:41 /usr/java/jdk1.5.0_10/bin/java -Djava... > > Expecting to find that I had some error in my webapp I did a few thread > dumps, but assuming that nid in the thread dump corresponds to pid from > ps I found that the process that was spinning was "VM Thread": > > "VM Thread" prio=1 tid=0x08098a48 nid=0x144 runnable > > The thread dump does not give any additional information about this > thread. I presume it is the Virtual Machine itself. > > If I look at the system status using the Tomcat manager webapp there are > often requests listed with ridiculously large values in the Time column, > several hundred seconds for jsp pages that only take a fraction of a > second to generate, and I can cut an paste the request into my browser > and the request will finish in a fraction of a second. > > Sometimes it seems that reloading some of the webapps can "fix" the > problem, at least for a while - I don't know for sure, it could be > coincidence, but if I don't do anything the problem can persist for long > periods of time and then go away after a few webapp reloads. I have > tried to detect a pattern about which app reload solves the problem but > it seems to be different different times. vmstat doesn't show the > machine as thrashing or using much IO (everything basically fits into > physical memory). The only thing I can think of is that the VM is going > into a marathon garbage collection phase, but I don't know how to test > that hypothesis, and it seems odd that even that could go on for lengthy > periods of time. > > Help?!? > > JVM: jdk1.5.0_10 > Tomcat: apache-tomcat-6.0.13 > uname -a: Linux [hostname here] 2.4.34-grsec #27 SMP Mon Jan 22 21:19:29 > CST 2007 i686 unknown > > The system is a two cpu system with 4GB RAM, and when not in this > spinning state it handles its load with 10-15% cpu load. > > > --------------------------------------------------------------------- > To start a new topic, e-mail: users@tomcat.apache.org > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > -- "Houston, we have a problem." --------------------------------------------------------------------- To start a new topic, e-mail: users@tomcat.apache.org To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
