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From Paolo Santarsiero <paolo.santarsi...@gmail.com>
Subject Re: Tomcat dies suddenly (was JVM goes away)
Date Wed, 13 Jan 2010 13:58:55 GMT
In order to monitor java memory at chrash time you can add to JAVA_OPTS
these directives

-XX:+HeapDumpOnOutOfMemoryError
-XX:HeapDumpPath=/your/tomcat/folder/memorydump.hprof

In this way, if tomcat goes in out of memory, you have an image of memory
(memorydump.hprof) that you can analyze by an external application like
MemoryAnalyzer [ http://www.eclipse.org/mat/ ].

2010/1/13 Carl <carl@etrak-plus.com>

> From the original posting:
>
> This is a new server, a Dell T110 with a Xeon 3440 processor and 4GB
> memory.  I have turned off both the turbo mode and hyperthreading.
>
> The environment:
>
> 64 bit Slackware Linux
>
> java version "1.6.0_17"
> Java(TM) SE Runtime Environment (build 1.6.0_17-b04)
> Java HotSpot(TM) 64-Bit Server VM (build 14.3-b01, mixed mode)
>
> Tomcat: apache-tomcat-6.0.20
>
> These are the current JAVA_OPTS="-Xms1024m -Xmx1024m -XX:PermSize=368m
> -XX:MaxPermSize=368m"
>
> In the previous posting, I noted that I have observed the memory usage and
> general performance with Java VisualVM and have seen nothing strange.  GC
> seems to be performing well and the memory rarely gets anywhere near the
> max.  New information: I thought I was seeing GC as memory usage was going
> up and down but in fact it was mostly people coming onto the system and
> leaving it.  After several hours, the memory settles to a baseline of about
> 375MB.  Forced GC never takes it below that value and the ups and downs from
> the people coming onto and leaving the system also returns it to pretty much
> that value.  The maximum memory used never was above 700MB for the entire
> day.
>
> The server runs well, idling along at 2-5% load, except for a quick spike
> during GC, serving jsp's, etc. at a reasonable speed.  Without warning and
> with no tracks in any log (Tomcat or system) or to the console, the JVM will
> just go away, disappear.  New information: The JVM does not just go away but
> somehow Tomcat shutsdown as the ports used by Tomcat are closed (pointed out
> by Konstantin.)  Sometimes, the system will run for a week, sometimes for
> only several hours.  Initially, I thought the problem was the turbo or
> hyperthreading but, no, the problem persists.
>
> When Tomcat shuts down, the memory that it held is still being held (as
> seen from top) but it is nowhere near the machine physical memory.
>
> The application has been running on an older server (Dell 600SC, 32 bit
> Slackware, 2GB memory) for several years and, while the application will
> throw exceptions now and then, it never crashed.  This lead me to believe
> the problem had something to do with the 64 bit JVM but, with without seeing
> errors anywhere, I can't be certain and don't know what I can do about it
> except go back to 32 bit.
>
> New information.
>
> Last evening, I observed the heap and permGen memory usage with Visual JVM.
>  It was running around 600MB before I forced a GC and 375MB afterward.
>  Speed was good.  Memory usage from top was 2.4GB.  Five minutes later,
> Tomcat stopped leaving no tracks that I could find.  The memory usage from
> top was around 2.4GB.  The memory usage from Visual JVM was still showing
> 400MB+ although the Tomcat process was gone.  I restarted Tomcat (did not
> reboot) so Tomcat had been shutdown gracefully enough to close the ports
> (8080, 8443, 443.)  Tomcat stayed up for less than an hour (under light
> load) and stopped again.  The memory used according to top was less than 3GB
> but I didn't get the exact number.  I restarted it again (no server reboot)
> and it ran for the rest of the night (light load) and top was showing 3.3GB
> for memory this morning.
>
> I brought up a new server last night and have switched to that server for
> production (same Linux, JDK, server.xml, JAVA_OPTS, etc.).  It would seem if
> the problem is with my application or the JVM, that the problem will follow
> me to the new server.
>
> Anyone have any ideas how I might track this problem down?
>
> Thanks,
>
> Carl

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