[GHC] #13164: idle time full GCs (idle cpu usage)

[GHC]

#13164: idle time full GCs (idle cpu usage)
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        Reporter:  lspitzner         |                Owner:
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Runtime System    |              Version:  8.0.1
      Resolution:                    |             Keywords:  idle GC
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by rwbarton):

 FWIW I've never cared about deadlock detection, and it sounds unreliable
 in view of lspitzner's most recent comment. I do care that interactive
 programs I'm not actively using don't consume 12% of my CPU. Doing a GC
 when the user isn't interacting with the program sounds like a good idea
 to hide latency.

 Judging from the detailed GC statistics lspitzner's program isn't totally
 idle; it must be doing a little bit of work every second, repeatedly
 triggering a new idle GC. But one would expect it to be cheap to do a
 little bit of work every second. The heap could be a lot bigger than 50
 MB...

 The user's guide suggests enabling the idle GC for interactive programs,
 but when there is a little work to do every second it seems basically
 unusable. And the effects of the idle GC would be lost completely by doing
 work every 0.2 seconds, which is strange.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13164#comment:5>
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