[Beowulf] Controlling java's hunger for RAM
samuel at unimelb.edu.au
Mon Feb 20 19:39:37 PST 2012
-----BEGIN PGP SIGNED MESSAGE-----
A perennial issue on our x86 clusters is Java and its
unpredictableness for wanting RAM. It seems it defaults to trying to
mmap() a quarter of system RAM (12GB on our 48GB nodes for instance)
unless overridden by the -Xmx parameter.
Now we'd like a way to be able to set a default for -Xmx for all Java
processes, but cannot use $_JAVA_OPTIONS as that overrides the command
line options rather than the other way around (which would have been
the sensible way to do it).
The reason why is that Torque sets RLIMIT_RSS to enforce memory
requests on jobs, and malloc() now usually calls mmap() to allocate
rather than sbrk() so RLIMIT_DATA is useless (not enforced).
Christopher Samuel - Senior Systems Administrator
VLSCI - Victorian Life Sciences Computation Initiative
Email: samuel at unimelb.edu.au Phone: +61 (0)3 903 55545
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.11 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
-----END PGP SIGNATURE-----
More information about the Beowulf