Debugging ASP.Net shared pool techniques

I work for a hosting company, providing ASP.Net 3.5 hosting. Honestly, we usually provide quite good uptime and velocity. However, we are having problems with one of our shared pools. As u开发者_StackOverflow社区sual, we try to maximize the number of webs that can run into one pool.

Lately we are suffering continuous hangs. The process doesn't crash, but starts to show OutOfMemoryExceptions or stops processing requests. We think this is responsability of one of the applications (it would be great to know which one).

I have some memory dumps that I have processed with WinDbg. I've run f.e:

!dumpheap -stat

This method provide global memory usage of objects. Nothing remarkable... Also I've checked:

~*e!clrstack 

I see various non managed threads. In those who are managed appears stacks like:

[HelperMethodFrame_1OBJ: 0f30e320]            
System.Threading.WaitHandle.WaitMultiple(System.Threading.WaitHandle...
0f30e3ec 7928b3ff System.Threading.WaitHandle.WaitAny(System.Threading...
0f30e40c 7a55fc89 System.Net.TimerThread.ThreadProc()...
0f30e45c 792d6e46 System.Threading.ThreadHelper.ThreadStart_Context(System...
0f30e468 792f5781 System.Threading.ExecutionContext.runTryCode(System...

At least, I haven't seen exception throwing or similar (in that moment). I've also had access to two scripts written by Tess Ferrandez for calculating the number of sessions and size. Also here not promising results. Anything peculiar or remarkable (24000 bytes as average).

I would like to know what kind of strategies are you usually using facing this kind of problems. Have you ever used Microsoft Support?

Thanks a lot!

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Very nice question, well a bad asp.net can hang all shared web apps on the same pool...

Ok let see... if the problem is on memory, get the VMMap from Sysinternals, and also the Process Explorer

Run them both, and from Process explorer find the PID number of pool that you wish to investigate, its under the inetinfo.exe, and have probably the name aspnet_wp.exe.

Now on the VMMap add for monitoring this Pool using for help the PID, and voila, you see the memory and the open images (aspx files) that probably are a lot and make the problems... The files that you going to see are located on temporary of asp.net Framework, but you can connect them and see from witch site they come from.

Well if the problem is not on memory, but the programmer have create bad loops, or even create thread sleeps, then I think process explorer is a way to investigate the pools and search for whats eating the power.

Additional

Maybe a pool recycle every 15minute can solve this issue ?

More about

In those videos there are a lot of informations about VMMap and memory manager. Mysteries of Windows Memory Management, Part 1, and , Part 2

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There are many tools, but it sounds like your main goal is to determine what's causing the problem. This can be done very simply with a binary search.

Break the pool in half, and see which one crashes. Repeat until you have a crashed pool with only one application in it.

This is already O(log2n), but you can speed the process up arbitrarily by dividing into more than two sub-pools.