Re: How to ease the burden on the Garbage Collector?
Re: How to ease the burden on the Garbage Collector?
- Subject: Re: How to ease the burden on the Garbage Collector?
- From: Jens Alfke <email@hidden>
- Date: Fri, 9 Oct 2009 21:05:22 -0700
On Oct 9, 2009, at 7:23 AM, Gabriel Zachmann wrote:
http://zach.in.tu-clausthal.de/tmp/malloc1.png
http://zach.in.tu-clausthal.de/tmp/malloc2.png
http://zach.in.tu-clausthal.de/tmp/malloc3.png
Those are showing all malloc operations. Most of those are not garbage-
collected, so they don't affect GC time. (I'm not sure exactly what
symbol to trace if you want to watch just GC allocations.)
Are you sure you aren't just seeing the GC thread sitting and
waiting for something to do?
THat would mean that the GC thread does busy waiting, wouldn't it?
No, it's blocked on a semaphore. But it still shows up in samples or
backtraces (in mach_message_trap, usually.)
Here are the top lines of the call tree that I see in Shark.
It seems to me that they all belong to the same thread, the GC thread.
Yup, that shows about 20% (of a core) being spent in GC.
—Jens_______________________________________________
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