Biztalk 64 bit high CPU utilization

I started to deploy BizTalk server 2006 64-bit edition on Windows Server 2003 64-bit in our production environment and we noticed an unusual high CPU utilization by the BizTalk host processes.

The symptoms were twofold:

1. The BizTalk 64 bit servers suffered from a high CPU usage (one server had its CPU usage constantly stuck at 100%). This happened even when the load on the server was low, in fact much lower than on other BizTalk Server 32 bit machines running the same applications on a similar hardware.
The reason for the server high CPU usage was that some BizTalk host processes had their CPU usage stuck at a high value even if the BizTalk application(s) run by the host would process very few messages or no message at all. Actually, the CPU usage for those hosts would still be stuck at a high value even if the BizTalk application(s) run by the host were stopped!

2. Even when the CPU utilization was showing 100%, the server was still processing messages as fast as you would expect from a server under little load. No messages were queued for processing and no orchestrations were dehydrated!

Those 2 points gave me the feeling that nothing could be wrong with the BizTalk server itself (by that I mean the BizTalk code and the BizTalk installation) as the same code is running fine on 32 bit servers and as the performance monitor readings did not match the actual facts.

I requested help from Microsoft Support and they guided me to the KB 943165 which has a hotfix solving the high CPU usage problem I encountered on BizTalk Server 64-bit edition.
This hotfix fixes a problem brought by the security bulletin MS07-040, a security update for the .Net framework which brings CPU usage spikes on BizTalk Server 64 bit (meaning that the problem is only for the 64 bit version of the .Net framework). For information, Microsoft Support told me that the problem is suspected to be caused by an infinite loop in CounterManager.RunCacheThread when System.Threading.ThreadAbortException is raised.

I should also add that I could not actually find a Windows update directly related to the bulletin MS07-040 in the list of updates installed on the server running BizTalk Server 64-bit. Nevertheless, my Microsoft Support contact told me that the version of mscorwks.dll (found in c:\WINDOWS\Microsoft.NET\Framework64\v2.0.50727) has a timestamp showing that it is later than the hotfixes issued by bulletin MS07-040 and that the problem should then also occur with any later version of the dll (as it is a code change from that version on that brings the problem).

To conclude, would you encounter the same symptoms I enumerated above, you will want the check the KB 943165 and contact Microsoft Product Support to see if your case is applicable for this hotfix. They will then email you the details to download the hotfix.

I installed this hotfix on all my BizTalk Server 2006 64 bit machines and all of them are running smoothly now 🙂