[Mono-list] mono swallows threadpool exceptions

Daniel Hughes trampster at gmail.com
Wed Jul 21 05:16:41 EDT 2010

In trying to port our application to run on mono I have discovered
that mono is silently swallowing exceptions. This is a really big
deal, we expect these exceptions to bubble up and kill the

There is not even any indication that an exception has occurred it is just lost.

		public static void Main (string[] args)
			Action action = () =>
				throw new Exception("this should Kill the process but doesn't");
			ThreadPool.QueueUserWorkItem(_ => action());
				Console.WriteLine("wrongly still running");

The implications of this could be catastrophic. Imagine some code
which performs a check, finds bad data and throws an exception.
However mono swallows that exception so instead of the program closing
it carries on running and uses the bad data. This results in sensitive
data being lost. Or in our case a radio being bricked.

Can someone explain why mono is doing this and if their is some
setting / environment variable I can change to make unhandled
threadpool exceptions terminate the process as is expected.

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