[GHC] #8684: hWaitForInput cannot be interrupted by async exceptions on unix

[GHC]

#8684: hWaitForInput cannot be interrupted by async exceptions on unix
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        Reporter:  nh2               |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Core Libraries    |              Version:  7.6.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:  13497, 13525      |             Blocking:
 Related Tickets:  #12912, #13525    |  Differential Rev(s):  Phab:D42
       Wiki Page:                    |
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Comment (by nh2):

 In other words, I believe we have a scheduling unfairness problem in the
 non-threaded RTS:

 A thread that loops tightly around a foreign call will never give other
 threads the chance to run.

 I ''suspect'' this is because of the run-queue logic mentioned in
 [https://ghc.haskell.org/trac/ghc/wiki/Commentary/Rts/Scheduler#Therunqueue
 the Scheduler commentary]:


 ----


 > In more detail, threads are put **in front** (`pushOnRunQueue`) if:
 > [...]
 > * In the non-threaded runtime, when a thread waiting on IO unblocks.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8684#comment:22>
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