[GHC] #4934: threadWaitRead works incorrectly on nonthreaded RTS

[GHC]

#4934: threadWaitRead works incorrectly on nonthreaded RTS
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        Reporter:  slyfox                       |            Owner:
            Type:  bug                          |           Status:  patch
        Priority:  normal                       |        Milestone:  ⊥
       Component:  Runtime System               |          Version:  7.0.1
      Resolution:                               |         Keywords:
Operating System:  Linux                        |     Architecture:  x86_64
 Type of failure:  Incorrect result at runtime  |  (amd64)
       Test Case:                               |       Difficulty:
        Blocking:                               |  Unknown
                                                |       Blocked By:
                                                |  Related Tickets:
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Comment (by slyfox):

 If idea in patches looks fine i can squash last 3 patches in one and
 cleanup comments around.

 I can also slightly change polling cycle to resume only descriptors with
 data available,
 and not all the waiters. It would be more robust against spurious blocking
 calls.

 What do you think?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/4934#comment:21>
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