#6283: [with patch, positive review] Make it so NUM_THREADS is set intelligently
instead of idiotically in makefile so doing "make ptest" or "make
ptestlong" doesn't kill some computers
-----------------------+----------------------------------------------------
Reporter: was | Owner: jhpalmieri
Type: defect | Status: assigned
Priority: major | Milestone: sage-4.1.2
Component: doctest | Keywords:
Reviewer: Dan Drake | Author: John Palmieri
Merged: |
-----------------------+----------------------------------------------------
Comment(by mvngu):
The file `SAGE_ROOT/makefile` has been manually patched to include the
changes in `makefile.patch`. I have also included a warning about using
the default value of zero, i.e. having `NUM_THREADS=0` which is the
default:
{{{
# NUM_THREADS is the number of threads to use for parallel testing
# (and sometime in the future, parallel building). If this is 0, then
# later it gets set to the number of processors -- see sage-ptest.
# The detection of number of processors might not be reliable on some
# platforms. On a Sun SPARC T5240 (t2.math), the reported number of
processors
# might not correspond to the actual number of processors. See ticket
#6283.
#
# WARNING: Unless you are certain that you want to use all the
cores/processors
# on your system for parallel doctesting, change the value of NUM_THREADS
to
# a (sensible) positive integer. The default value is zero.
NUM_THREADS=0 # default is zero
}}}
I think people should be made aware that having a value of zero means that
all the cores/processors on their system would be devoted to parallel
doctesting. On a personal machine, that's OK and any damage done would be
localized to the person's own machine. But on a multi-user machine such as
the machines making up the Sage cluster, bsd.math, etc., the default value
of zero can be dangerous because on sage.math, say, this would use 24
cores for parallel doctesting. Most of the time, people are running very
long jobs on sage.math, mod.math, and geom.math. Using all 24 cores on any
of these machines can have unexpected consequences such as having doctest
failures due to segfaults, out of memory error, and even bringing those
machines offline. The patch `trac_6283-warning.patch` also adds a warning
to this effect to the file `sage-ptest`. If you want to use the file
`SAGE_ROOT/makefile` for parallel doctesting, be absolute sure that you
have set a sensible positive integer for `NUM_THREADS`.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/6283#comment:6>
Sage <http://sagemath.org/>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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