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Tomcat gets high number of active sessions after restore of database

Tomcat gets high number of active sessions after restore of database

We are operating a Windchill cluster and had to restore a one day old database. Since this restore every time we start a node the servlet engine accumulates active sessions till it reaches around 430 active sessíons.

It seems nearly all of this connections are originating from localhost (20 GB in 5 hours).

The problem with this high number of active sessions is that tomcat eventually runs out of heap space and spends its time in full GC leaving the node unresponsive.

Thanks

Michael Stertz

3 REPLIES 3

Tomcat gets high number of active sessions after restore of database

Hi Michael, Check the following tomcat configuration file to see if
it is modified during the restore.
<tomcat_home>\conf\Catalina\localhost\Windchill.xml

Make sure that the Persistent Manager section is commented out or
atleast has some reasonable values.




Regards,
Pratahp


On Tue, Oct 14, 2008 at 2:20 AM, Michael Stertz
<->wrote:

> We are operating a Windchill cluster and had to restore a one day old
> database. Since this restore every time we start a node the servlet engine
> accumulates active sessions till it reaches around 430 active sessíons.
>
> It seems nearly all of this connections are originating from localhost (20
> GB in 5 hours).
>
> The problem with this high number of active sessions is that tomcat
> eventually runs out of heap space and spends its time in full GC leaving the
> node unresponsive.
>
> Thanks
>
> Michael Stertz
>
>

Tomcat gets high number of active sessions after restore of database

What release is this?

R8 M050 and R9 both have plenty of logging that can be enabled to track
when sessions are created and by what requests.

Two things to note:

1. When Tomcat is shutdown it persists the active sessions to disk
and when it is restarted it will initially restore them.
* They will still be dropped after a period of disuse, though
-- normally 30 minutes.
2. PTC or custom code can easily produce such a problem by doing
requests to localhost that require a session and then don't re-use
the same session between requests.
* Whoever has such code it should be fixed -- the logging
noted above should help track this down.

--
Jess Holle

Michael Stertz wrote:
>
> We are operating a Windchill cluster and had to restore a one day old
> database. Since this restore every time we start a node the servlet
> engine accumulates active sessions till it reaches around 430 active
> sessíons.
>
> It seems nearly all of this connections are originating from localhost
> (20 GB in 5 hours).
>
> The problem with this high number of active sessions is that tomcat
> eventually runs out of heap space and spends its time in full GC
> leaving the node unresponsive.
>
> Thanks
>
> Michael Stertz
>
>
>

AW: Tomcat gets high number of active sessions after restore of database

Thank you Jess and Prathap for responding.

As noted under 2. PTC or custom code can easily produce such a problem - IT DID!

Pure coincedence - at the same time with the database restore a new monitor was activated in the BigIP-Loadbalancer calling verify.jsp (aka LB keep alive) to check the operational state of the clusternodes. Unfortunately this script opens a new connection to tomcat every time it gets executed, which stays open after execution until timeout.

Michael
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