On Monday, May 5, 2014 4:41:39 PM UTC-7, William wrote:
>
> On Mon, May 5, 2014 at 4:16 PM, John H Palmieri
> <jhpalm...@gmail.com<javascript:>>
> wrote:
> >> -leif
> >>
> >> P.S.: If you haven't set MAKE, Sage "guesses" the number of threads to
> >> use to build the Sage library as well as the docs, AFAIK.
> >
> >
> > Right: Sage uses SAGE_NUM_THREADS to decide how many threads to use for
> > building spkgs and docs. If it's set to a number, that value gets used.
> > Otherwise, SAGE_NUM_THREADS gets set in src/bin/sage-env, using the
> Python
> > program src/bin/sage-num-threads.py:
> >
> > sage_num_threads_array=(`sage-num-threads.py 2>/dev/null || echo 1 2
> 1`)
> > SAGE_NUM_THREADS=${sage_num_threads_array[0]}
> >
> > This is documented in the installation manual, but maybe it should also
> be
> > in the top-level README.txt.
>
> There's something confusing going on here still. I just read the
> source to sage-num-threads.py and it outputs 3 numbers. The first is 1
> by default since I didn't set any environment variables, so despite my
> having 12 cores, SAGE_NUM_THREADS is 1. The others are 8 and 12, but
> according to sage-num-threads.py those are *only* used if I explicitly
> request something to happen in parallel, e.g., "make ptest". To
> quote the docs:
>
> "2) The number of threads to use when parallel execution is
> explicitly asked for (e.g. sage -tp)"
>
> I definitely only typed "make test" in my clean Sage install, so I did
> not explicitly ask for anything to be in parallel.
Building spkgs is by parallel by default, but I think it should be limited
by SAGE_NUM_THREADS.
> However, it looks
> like the doc building is in parallel anyways, which is the point when
> I ran out of RAM. So something seems misleading. Maybe 2 above
> really is
>
> "2) The number of threads to use when parallel execution is
> explicitly asked for (e.g. sage -tp), or when building the
> documentation (which is always in parallel!?)."
>
No: the number of threads used for docbuilding comes from SAGE_NUM_THREADS.
>From src/doc/common/build_options.py:
# Number of threads to use for parallel-building the documentation.
NUM_THREADS = int(os.environ.get('SAGE_NUM_THREADS', 1))
If you do "sage --sh -c 'export $SAGE_NUM_THREADS' " then you get "1",
right? By the way, I searched for SAGE_NUM_THREADS_PARALLEL, and it is only
used in src/sage/doctest/control.py, the doctesting framework.
--
John
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