[GHC] #7653: incorrect handling of StackOverflow exception in the event manager

[GHC]

#7653: incorrect handling of StackOverflow exception in the event manager
---------------------------------+------------------------------------------
    Reporter:  nus               |       Owner:  tibbe        
        Type:  bug               |      Status:  patch        
    Priority:  normal            |   Milestone:               
   Component:  libraries/base    |     Version:  7.7          
    Keywords:                    |          Os:  Linux        
Architecture:  Unknown/Multiple  |     Failure:  Runtime crash
  Difficulty:  Unknown           |    Testcase:               
   Blockedby:                    |    Blocking:               
     Related:                    |  
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Comment(by kazu-yamamoto):

 Thank you for explanation.

 Your patch can be applied to GHC/Event/TimerManager.hs. Unfortunately, the
 following error happens with/without your patches:

 {{{
 rplfrk: user error (Pattern match failure in do expression at
 libraries/base GHC/Event/Thread.hs:212:3-10)
 }}}

 The code is here:

 {{{
 getSystemTimerManager :: IO TM.TimerManager
 getSystemTimerManager = do
   Just mgr <- readIORef timerManager
   return mgr
 }}}

 What should getSystemTimerManager do when readIORef returns Nothing?

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7653#comment:8>
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