Chris,
Carl: when the JVM "dies" and you use top to see free memory, does it
say that 2.4GB of memory is in use by a particular process,
It shows the 2.4GB as 'Used' but does not show it attached to any process
(remember that the Tomcat process has disappeared... ps aux | grep tomcat
yields nothing.) My observation is that the server has 500MB 'used' when it
starts and moves to 2.4GB after Tomcat is started. However, the server does
not appear to reclaim the memory after the process dies as the 'used' stays
right at 2.4GB. Visual LVM continues to report that the now dead Tomcat
instance is still holding onto the memory but I am not certain whether this
reflects some variable(s) set in Visual JVM or the actual memory something is
still holding onto.
or does it
just appear that the memory is not "available"?
The 2.4GB is just shown as 'Used' by top.
If it's by a particular
process, which one?
No process but I expected that as the Tomcat process (ps aux | grep tomcat) no
longer exists (after the 'crash'.)
The JVM process ("/usr/bin/java" or whatever) either
does or does not exist, and if it does not exist, is it retaining
memory?
I don't know how I could tell if the Tomcat java process/JVM was holding onto
the memory if the process no longer exists.
If the Tomcat connectors have shut down (thereby releasing the
TCP/IP ports), but not the java process, then there should be some
indication in catalina.out
No indication at all... just comes to a stop. (I had a problem a while ago
with not properly releasing database connections an I still have a good deal of
stuff going to catalina.out (because I have been too busy to comment out the
debugging messages.)
that the connectors have been shut down
explicitly.
The whole thing sounds weird. :(
That has been a good deal of my frustration... I thought it would leave some
tracks somewhere.
All thoughts and ideas are appreciated.
Thanks,
Carl
----- Original Message -----
From: "Christopher Schultz" <ch...@christopherschultz.net>
To: "Tomcat Users List" <users@tomcat.apache.org>
Sent: Wednesday, January 13, 2010 11:50 AM
Subject: Re: Tomcat dies suddenly (was JVM goes away)
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Peter,
>
> On 1/13/2010 8:49 AM, Peter Crowther wrote:
>> Very difficult to know what the problem is. One thing you can now do
>> (as you've switched to another production server) is to run a memory
>> test across the "bad" server.
>
> Usually, I would agree that physical memory problems are likely to be a
> problem, but every time I've had a physical memory problem (much more
> common than I'd like to admit!), the JVM has crashed in a more classic
> way: that is, with an hs_log file and almost always with a SIGSEGV,
> rather than this phantom thing described by Carl.
>
> The Linux OOM killer might be a suspect, except that the process is
> apparently not dying, which is very strange.
>
> Carl: when the JVM "dies" and you use top to see free memory, does it
> say that 2.4GB of memory is in use by a particular process, or does it
> just appear that the memory is not "available"? If it's by a particular
> process, which one? The JVM process ("/usr/bin/java" or whatever) either
> does or does not exist, and if it does not exist, is it retaining
> memory? If the Tomcat connectors have shut down (thereby releasing the
> TCP/IP ports), but not the java process, then there should be some
> indication in catalina.out that the connectors have been shut down
> explicitly.
>
> The whole thing sounds weird. :(
>
> - -chris
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