Lieven Cardoen

Last week I got a call from a big customer saying that the 100 of the 200 candidates had just received an error log window in our Flex Application. I knew that this could happen someday, but what had caused this error log…?

After a lot of searching in the logs of the two servers at the customer, I found out that at a certain time on one of the two servers all sessions and application pool were ended. Why? Well, after again a lot of searching I found out that IIS recycles an application pool every 29 hours… Man, why is this default enabled???

Apparently a lot of these recycle events are nog logged by default. Only the 29 hour recycle event apparently is logged by default. As for now I haven’t found this log yet, so I will have to enable all those logs to find the actual reason why the application pool recycled…

That’s done by this command on IIS6:

cscript %SYSTEMDRIVE%inetpubadminscriptsadsutil.vbs Set w3svc/AppPools/LogEventOnRecycle 255

On IIS7 you can enable them in the Advanced Settings of the application pool.

The problem with our Flex Application was that it uses WebORB Authentication. This authentication is done by the first remote call after which the server side session remembers the credentials. After the recycle the sessions were gone and 100 candidates received a WebORB Security error… We have already solved this problem by re-authenticating when this happens but I’m also really hoping to find out why the application pool recycled in the first place… Any suggestions are welcome… (memory?, too mucht connections?, database problem?, …).

Ciao, Lieven Cardoen aka Johlero