#4322: High CPU usage during idle time due to GC
-------------------------------+--------------------------------------------
Reporter: hesselink | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: Runtime System | Version: 6.12.3
Keywords: idle GC | Testcase:
Blockedby: | Difficulty:
Os: MacOS X | Blocking:
Architecture: x86 | Failure: Runtime performance bug
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Comment(by simonmar):
It might help to add the timestamps too (`+RTS -vt`). Anyway, it looks
like between every two idle GCs the IO manager thread (thread 2) wakes up
one of the program threads (thread 29). I imagine you have a thread in
your program that is sitting in a loop calling `threadDelay`, with maybe a
1 second timeout?
I don't understand why this is happening:
{{{
a039a720: woken up on capability 1
a039a720: resuming capability 1
a039a720: giving up capability 1
a039a720: freeing capability 1
a039a720: woken up on capability 1
a039a720: resuming capability 1
a039a720: giving up capability 1
a039a720: freeing capability 1
a039a720: woken up on capability 1
a039a720: resuming capability 1
a039a720: giving up capability 1
a039a720: freeing capability 1
a039a720: woken up on capability 1
a039a720: resuming capability 1
a039a720: giving up capability 1
a039a720: freeing capability 1
}}}
that's the main thread waking up several times, and finding nothing to do
it goes back to sleep again.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4322#comment:3>
GHC <http://www.haskell.org/ghc/>
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