[GHC] #367: Infinite loops can hang Concurrent Haskell

[GHC]

#367: Infinite loops can hang Concurrent Haskell
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  Reporter:  simonpj                      |          Owner:  ezyang              
      Type:  bug                          |         Status:  new                 
  Priority:  lowest                       |      Milestone:  _|_                 
 Component:  Compiler                     |        Version:  6.4.1               
Resolution:  None                         |       Keywords:  scheduler allocation
        Os:  Unknown/Multiple             |   Architecture:  Unknown/Multiple    
   Failure:  Incorrect result at runtime  |     Difficulty:  Unknown             
  Testcase:                               |      Blockedby:                      
  Blocking:                               |        Related:                      
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Comment(by simonmar):

 I think we could incorporate the patch, but not turn on the flag by
 default.  If you want to work on it further and see if you can get the
 code size penalty down that would be great - my suggestion would be to do
 as I mentioned earlier and omit the yield check for functions which are
 guaranteed to yield within a finite time, because they only call other
 functions which have that property.  You can assume that calling an
 arbitrary closure or a primop is guaranteed to yield.  As a first step you
 can do the analysis within a module, the next step would be to extend it
 across module boundaries.

 We should check the primops to make sure that none of them hog the CPU for
 a long time.  I think `newArray#` has this problem, because it fills in
 the array in a loop, so for a large array it won't yield quickly.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/367#comment:29>
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