广泛使用ThreadAbortException

Question

I'm working in a legacy project that has this exception handling code in many methods.

catch(ThreadAbortException e)
{
  ...
}

I don't see anywhere in the project Thread.Abort() or Thread.Interrupt() calls. Is it safe to delete all these ThreadAbortException handling or it is some other way that can be raised.

Answer 1

Official docs: "The exception that is thrown when a call is made to the Abort method." If you are completely sure there are no calls to Thread.Abort then you might as well erase those catch blocks.

EDIT: Be mindful that your code may be running in the context of an external app that may call Thread.Abort on your threads.

Not that it matters anyway as a ThreadAbortException can't really be handled as the CLR itself will rethrow it to actually kill the thread ASAP.

"Actually yes, a ThreadAbortException is special. Even if you handle it, it will be automatically re-thrown by the CLR at the end of the try/catch/finally. (As noted in the comments, it can be suppressed with ResetAbort but by that point the code smells like rotten fish.)" - Read this question for more details: ThreadAbortException

Answer 2

Well if answering specifically your question I would say that it would be better not to delete these exception handlers as it's most likely that they were added by some developer trying to solve a problem. And I think there was a reason to add those handlers so if you just remove this code it can lead to appearing of some bugs again in the future.

Regarding the ThreadAbordException : I know for sure that it can be throwed not only with calling Thread.Abort() method when you are debugging (it might be a bug in VS, I'm not sure) and it forces your program to just crash silently. So depending on what's inside of those handlers it could be possible that a developer was trying to solve such problem.

Also remember that you could be invoking methods of third-party libraries, web-services etc. in a separate thread, too. I'm not sure if they can throw such an exception but that's a possible case to consider.

Answer 3

Is the project running on a main thread and spinning up background worker threads? If the main thread exits while background threads are running, a ThreadAbortedException can occur on the background threads.

The catch statement could specifically handle this scenario, where no error actually occurred on the background thread, in a different manner than any other exception.