Why isn't IIS cleaning up the old worker processes (w3wp.exe) on pool recycle leading to website out of memory exception?
I have an asp.net-mvc site and recently I am getting an out of memory exceptions on my web server. I only have 1 application pool and we recent set IIS to recycle after it hits a certain limit. I went in the other day and saw 4 w3wp.exe processes running (each with ~1.8GB memory being used)
I assume that during the recycle process, it's not killing the old worker process and eventually I get out of memory exceptions on my website because the box only has 8GB memory. I can add memory to the box but I am concerned why these old processes are not being cleaned up.
Are there any recommendations to figure out why this recycle process is not killing the old w3wp.exe processes and leaving them running? Any suggestions around understand both root cause or even workarounds to avoid this risk going forward?
Answer
Application pool recycle usually shuts down old worker processes, so I don't think you hit a bug of IIS.
Note that processes can live longer if they become orphaned, and based on configuration IIS must leave them there for you to troubleshoot,
https://www.iis.net/configreference/system.applicationhost/applicationpools/add/failure
If you are not quite familiar with debugging such processes, I suggest you open a support case via http://support.microsoft.com and let Microsoft support guys help you out.