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Re: Memory allocation jump after running for a while with a largenumber of threads



Dan Kegel wrote:
Hrvoje Niksic wrote:

Strangeness in general, or do you have something specific in mind?

The periodic burps caused by the GC, say. Us C programmers will blame all your suddent memory consumption jumps on that without even looking at the evidence :-)

GC managed memory is restricted to 250M, which is mentioned (in earlier email) by the command line option "-Xmx250m". I've verified the memory map that Hrvoje sent to me in a private email. No, we didn't overcommit anything.

What's interesting are numerous 992K map'ed memory regions (Note there
is a 1M hole between every 992K chunk and the next 32K):

[...]
bdf00000 (32 KB)       rw-p (00:00 0)
bdf08000 (992 KB)      ---p (00:00 0)
be100000 (32 KB)       rw-p (00:00 0)
be108000 (992 KB)      ---p (00:00 0)
be300000 (32 KB)       rw-p (00:00 0)
be308000 (992 KB)      ---p (00:00 0)
be500000 (32 KB)       rw-p (00:00 0)
be508000 (992 KB)      ---p (00:00 0)
be700000 (32 KB)       rw-p (00:00 0)
be708000 (992 KB)      ---p (00:00 0)
[...]

They aren't from JVM, as we mmap with rwx- (for heap, generated code,
etc) and/or ---p (for guard pages; no, we don't use 992KB guards).
Chances are they either came from kernel or libc.

thanks,
-hui





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