Can withAsync guarantee that its child will be terminated if the thread
executing withAsync gets an exception?
To remind, here's an implementation of withAsync:
withAsyncUsing :: (IO () -> IO ThreadId)
-> IO a -> (Async a -> IO b) -> IO b
-- The bracket version works, but is slow. We can do better by
-- hand-coding it:
withAsyncUsing doFork = \action inner -> do
var <- newEmptyTMVarIO
mask $ \restore -> do
t <- doFork $ try (restore action) >>= atomically . putTMVar var
let a = Async t (readTMVar var)
r <- restore (inner a) `catchAll` \e -> do cancel a; throwIO e
cancel a
return r
I am interested in the case when an exception arrives which transfers
control to 'cancel', and then another exception arrives to the same
thread. Even though 'catchAll' (which is a type-restricted synonym for
catch) masks the exception handler, 'throwTo' inside 'cancel' is
interruptible (as stated by the documentation).
Will this scenario lead to a thread leakage?
Roman
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