运行单元（集成）测试时，ContextSwitch死锁

Question

We get the following error when running at test:

ContextSwitchDeadlock was detected
Message: The CLR has been unable to transition from COM context 0x344b0c0 to COM 
context 0x344b230 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.

The test does a WCF call to a method on the service layer that gets data from the database using Entity Framework. Data is also Cached on the server side using EntLib Caching Application Block.

The test that tests the same code on the server side passes without error.

Answer 1

Found the problem.

We were not closing the WCF proxies correctly. We were using "using" instead of a try catch with close or abort.

Therefore, an error in one test would cause a ContextSwitchDeadlock in a subsequent test that tried to use the same WCF service.