[GHC] #9379: Blocked STM transaction is not interruptible

29 Jul 2014

      #9379: Blocked STM transaction is not interruptible
-------------------------------------+-------------------------------------
       Reporter:  Feuerbach          |                   Owner:  simonmar
           Type:  bug                |                  Status:  new
       Priority:  normal             |               Milestone:
      Component:  Runtime System     |                 Version:  7.8.3
       Keywords:                     |        Operating System:
   Architecture:  Unknown/Multiple   |  Unknown/Multiple
     Difficulty:  Unknown            |         Type of failure:
     Blocked By:                     |  None/Unknown
Related Tickets:                     |               Test Case:
                                     |                Blocking:
                                     |  Differential Revisions:
-------------------------------------+-------------------------------------
 {{{#!hs
 import Control.Exception
 import Control.Concurrent
 import Control.Concurrent.STM
 import Foreign.StablePtr

 main :: IO ()
 main = do
   tv <- atomically $ newTVar True
   _ <- newStablePtr tv
   t <- mask_ $ forkIO (blockSTM tv)
   killThread t

 blockSTM :: TVar Bool -> IO ()
 blockSTM tv = do
   atomically $ do
     v <- readTVar tv
     check $ not v
 }}}

 This code blocks forever. As I understand it, since the transaction
 blocks, it should be interruptible even despite the mask, and so
 killThread must succeed here, and the program should finish promptly.

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9379
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler