Thursday, May 13, 2010

ContextSwitchDeadlock was detected

I have been writing an application that loads large amounts of data into the a database. The process of loading the data into the database goes through several steps requiring a considerable amount of time to complete. The long processing time is not a matter of concern from the application stand point. However, frequently the application throws a "ContextSwitchDeadlock was detected" message that says the following:

Message: The CLR has been unable to transition from COM context 0x20450a0 to COM context 0x20452f0 for 60 seconds. The thread that owns the destination context/apartment is most likely either doing a non pumping wait or processing a very long running operation without pumping Windows messages. This situation generally has a negative performance impact and may even lead to the application becoming non responsive or memory usage accumulating continually over time. To avoid this problem, all single threaded apartment (STA) threads should use pumping wait primitives (such as CoWaitForMultipleHandles) and routinely pump messages during long running operations.

From the information I have read on the web, this problem relates to the way the CLR works. As the running thread is not sending any massage for the duration of the load period, the CLR interprets this as a possible deadlock situation. The way to avoid this, is to create a new thread that will be responsible for the lengthy process, thus the main thread is "free".

Apparently, the CLR only shows this message in debug mode and not in release mode. Up to now I have been running the application on debug mode. I have not run it on release mode. I don't really experience this problem on a regular enough "schedule" for it to be reproducible.

Avoiding the "ContextSwitchDeadlock was detected" message on debug mode.

There seems to be a way of avoiding getting this error message while running the application in debug mode. I will try it out, and in case it does not work I will update the post. In order to accomplish this in Visual Studio your need to open the Exceptions dialog (Ctrl+Alt+E). Under Managed Debugging Assistants you should uncheck the throw checkbox.
Feel free to link to this post or write a comment if it has solved your problem. This way other people are more likely to find it :) 

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