[GHC] #15366: GHC.Conc.Windows has a surprising queue

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[GHC] #15366: GHC.Conc.Windows has a surprising queue

GHC - devs mailing list
#15366: GHC.Conc.Windows has a surprising queue
-------------------------------------+-------------------------------------
           Reporter:  dfeuer         |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:  8.8.1
          Component:  Core           |           Version:  8.4.3
  Libraries                          |
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Runtime
  Unknown/Multiple                   |  performance bug
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 `GHC.Conc.Windows` seems to use `[DelayReq]` as a priority queue, and uses
 `foldr` to insert multiple elements into it. Unless these lists are always
 very short (are they?) that seems like a bad idea.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15366>
GHC <http://www.haskell.org/ghc/>
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Re: [GHC] #15366: GHC.Conc.Windows has a surprising queue

GHC - devs mailing list
#15366: GHC.Conc.Windows has a surprising queue
-------------------------------------+-------------------------------------
        Reporter:  dfeuer            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Core Libraries    |              Version:  8.4.3
      Resolution:                    |             Keywords:
Operating System:  Windows           |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by dfeuer):

 * os:  Unknown/Multiple => Windows


--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15366#comment:1>
GHC <http://www.haskell.org/ghc/>
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Re: [GHC] #15366: GHC.Conc.Windows has a surprising queue

GHC - devs mailing list
In reply to this post by GHC - devs mailing list
#15366: GHC.Conc.Windows has a surprising queue
-------------------------------------+-------------------------------------
        Reporter:  dfeuer            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Core Libraries    |              Version:  8.4.3
      Resolution:                    |             Keywords:
Operating System:  Windows           |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by dfeuer):

 * cc: simonmar (added)


Comment:

 CCing Simon Marlow, because he seems to have written this bit.

 Is there some reason to use a list here rather than some sort of heap? The
 list version is around `O(n^2)`ish. With a heap, pending delays would be
 inserted into a heap, then when the time came merged with the heap of
 existing delays. The whole thing would be `n log n`ish and probably rather
 fast. A pairing heap should work pretty well, although something with
 better real-time bounds might be better for preventing main-loop stalls.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15366#comment:2>
GHC <http://www.haskell.org/ghc/>
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Re: [GHC] #15366: GHC.Conc.Windows has a surprising queue

GHC - devs mailing list
In reply to this post by GHC - devs mailing list
#15366: GHC.Conc.Windows has a surprising queue
-------------------------------------+-------------------------------------
        Reporter:  dfeuer            |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Core Libraries    |              Version:  8.4.3
      Resolution:                    |             Keywords:
Operating System:  Windows           |         Architecture:
 Type of failure:  Runtime           |  Unknown/Multiple
  performance bug                    |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4967
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by dfeuer):

 * status:  new => patch
 * differential:   => Phab:D4967


--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15366#comment:3>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler

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