Re: [Wrapper-user] Notification for JVM Hungs

[Leif M. <lei...@ta...>]

Karthik,
JVM restarts like this are usually caused by the JVM itself freezing
and needing to be restarted.   There are however times where the JVM
is temporarily frozen by heavy disk IO or memory swapping.   If you
are seeing this problem repeatedly, I would suggest setting the
wrapper.ping.timeout to a longer value and seeing if the JVM recovers
on its own.   Whether it is a permanent or temporary freeze, there is
a problem that needs to be resolved as your application will not be
responsive to user requests when it is unable to respond to the
Wrapper's pings.

When the JVM is restarted, the first JVM is first shutdown.    What
version of the Wrapper are you using though?  There was a problem
fixed in 3.3.1 where the Wrapper was sometimes failing to actually
kill a JVM process which it decided to kill.   If you are having this
problem then you will need to upgrade.   Depending on the OS you are
running, it is also possible that the ports are still in a locked
state until their timeout has expired.   In this case, you may want to
try increasing the delay before launching the second JVM instant.  You
can do this with the wrapper.restart.delay property.
http://wrapper.tanukisoftware.com/doc/english/prop-restart-delay.html

The professional edition of the Wrapper makes it possible for you to
launch an external process at various points in the Wrapper and JVM
lifecycle.  This includes just before a JVM restart:
http://wrapper.tanukisoftware.com/doc/english/props-event.html#command

Please let me know how these options work for you.

Cheers,
Leif


On Sun, Sep 11, 2011 at 5:30 AM, karthik Krishnan <kar...@gm...> wrote:
>
> Hi,
>
> Reposting due to some mailing list subscription issue!!! Please ignore if
> this is repeated. Inconvenience regretted..
>
> I m facing issues like, when the JVM Hungs and restarts with below message..
> sometimes, few services are not bound properly and giving us some issues..
>
> wrapper  | JVM appears hung: Timed out waiting for signal from JVM.
> wrapper  | Java Virtual Machine did not exit on request, terminated
> wrapper  | Launching a JVM...
> jvm 2    | Initializing...
>
> So, i need to write a program which will be called whenever the JVM Hungs
> and restarts by itself to check if the services are bound properly. for that
> i need to know, from where can i invoke this program.. (Likely to call a
> batch file from somewhere..).. Need to know which file and steps the Wrapper
> calls to restarts the service..
>
> Or, is there any property that can be set to send a notification by mail
> when there is a JVM Hung.. I know there is a email Notification available in
> prof edition. We are using a standard edition.
> Can someone help me or let me know if u have done something similar to this.
>
> Someone can throw light on why this happens.. and what could be done to
> avoid such JVM Hang and restarts.
>
> Any help in this regard will be useful
>
> Thanks in Advance,
>
> Regards,
> Karthik Krishnan