Some of our servers were getting 100% CPU.
When analyzed through Performance Counters, we found that Application Restarts counter increased by 50 when CPU reached 100% but the Worker Process Restarts count is 0.
It seems to be most of our sites are getting restarted every hour. We have 60 sites hosted in the server and each site has separate app pool.
We have even check the WAS event logs. But there are no logs for App Pool Recycle. We have already enabled all app pool recycle logging event.
Is there any other logging which can help to find this issue?
After analyzing all the configuration in those web servers, we found there was a scheduler which run every hour to clear the temporary internet files of ASP.net which are old.
There was a bug in that scheduler due to which it clear all the files which are in use by IIS also. This might be triggering the application restart.
After disabling the scheduler, Application Restarts counter increases by 5 at that given point when the scheduler was running and there was a normal CPU usage at that point.
But still we have some issues, Application Restarts counter increased by 200 in a span of 2 hours. But CPU is running normal since no of sites getting restarted are very less.