throwTo can block indefinitely when target thread finishes with exceptions blocked

throwTo can block indefinitely when the target thread has exceptions blocked at thread creation time. The following test program demonstrates this problem.

import Control.Exception
import GHC.Conc
  
main = do
    t1 <- block $ forkIO yield
    t2 <- forkIO $ killThread t1
    threadDelay 1000000
    threadStatus t1 >>= print
    threadStatus t2 >>= print

can print (and does fairly reliably for me)

ThreadFinished
ThreadBlocked BlockedOnException

See also http://www.haskell.org/pipermail/reactive/2009-January/000197.html

Trac metadata

Trac field	Value
Version	6.10.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Runtime System
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system	Linux
Architecture	x86