[GHC] #15642: Improve the worst case performance of weak pointers

[GHC]

#15642: Improve the worst case performance of weak pointers
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        Reporter:  dfeuer            |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:  8.8.1
       Component:  Runtime System    |              Version:  8.6.1-beta1
      Resolution:                    |             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:                    |
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Comment (by dfeuer):

 Replying to [comment:9 osa1]:
 > Hmm I think (1) is a good idea. Just one traversal over all weaks before
 GC to tag keys, then any live key will be untagged during evacuation. (did
 I get this right?)

 Sounds right to me.

 > Out of curiosity, are you observing any slowness/long pauses in a real
 program because of collecting weaks?

 I've never written a practical program using weak references. I just think
 worst-case quadratic time garbage collection sounds pretty bad. Can we fix
 it without making more common cases worse? Dunno, but I think it's worth
 trying.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15642#comment:10>
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