[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 simonmar):

 > I just noticed that this means that you do not get deadlock detection if
 you forkIO (forever (threadDelay 100000)). That's interesting.

 Probably because it never runs a major GC, only minor GCs.  Admittedly
 that's surprising and counter-intuitive.

 > I do care that interactive programs I'm not actively using don't consume
 12% of my CPU.

 I'm sympathetic to that.  Like I said, I'm open to suggestions here.  I do
 worry that not having deadlock detection by default will be surprising -
 it's quite useful when developing/debugging, for instance.  We have lots
 of tests in `testsuite/tests/concurrent` that rely on it.

 How about we give the idle GC a time budget expressed as a % of wall clock
 time?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13164#comment:6>
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