How can I exit the program from a sigTERM handler?

Question

Consider something like this:

...

handleShutdown :: ThreadId -> IO ()
handleShutdown tid = doSomethingFunny >> throwTo tid ExitSuccess

main = do
    ...
    installHandler sigTERM (Catch $ myThreadId >>= handleShutdown) Nothing
    forever $ do
        stuff
    ...

If sigINT (Ctrl+C) is handled in this manner, the process finishes nicely. However, it seems like sigTERM is being used by Haskell internally and the code above doesn't exit from the main process at all. Is there a way to exit the process from a sigTERM handler without using an MVar and a custom loop? I couldn't find any information on the sigTERM handling anywhere (didn't read ghc sources, that's just too much for me to handle).

Update:

The following works:

main = do
    ...
    tid <- myThreadId -- This moved out of the Catch handler below.
    installHandler sigTERM (Catch $ handleShutdown tid) Nothing
    forever $ do
        stuff
    ...

Answer 1

Sorry for short answer, but on mobile.

You want to run myThreadId from outside of the handler itself to get the main thread's ID. You're currently getting the ID of the signal handler itself.