Hi all,
I have been working on a project that involves a Julia front-end calling a
C back-end (it's a neural network simulator, in case you're wondering).
Since the C side is essentially a bunch of nested for-loops, I've been
experimenting with using Cilk+ (via GCC5) to parallelize things. Loading
and running the C code from within a Julia session works just fine, both
from the command-line and from Jupyter. But using Cilk somehow messes with
PyPlot.
Specifically, here is a minimal example that produces the problem I see in
Jupyter (relevant code below):
In [1]: include("hello.jl")
hello 5
hello 0
hello 2
hello 1
hello 6
hello 3
hello 4
hello 7
hello 8
hello 9
In [2]: using PyPlot
Warning: error initializing module PyPlot:
ErrorException("Failed to pyimport("matplotlib"): PyPlot will not work until
you have a functioning matplotlib module.
For automated Matplotlib installation, try configuring PyCall to use the Conda
Python distribution within Julia. Relaunch Julia and run:
ENV["PYTHON"]=""
Pkg.build("PyCall")
using PyPlot
pyimport exception was: PyError (:PyImport_ImportModule) <type
'exceptions.AttributeError'>
AttributeError('_ARRAY_API not found',)
File "/usr/local/lib/python2.7/site-packages/matplotlib/__init__.py", line
180, in <module>
from matplotlib.cbook import is_string_like
File "/usr/local/lib/python2.7/site-packages/matplotlib/cbook.py", line 34,
in <module>
import numpy.ma as ma
File "/usr/local/lib/python2.7/site-packages/numpy/ma/__init__.py", line 46,
in <module>
from . import core
File "/usr/local/lib/python2.7/site-packages/numpy/ma/core.py", line 30, in
<module>
import numpy.core.umath as umath
")
The code:
hello.jl:
module hello ccall((:hello, "hello.dylib"), Void, (Cint,), 10) end#module
hello.c:
/** compile with gcc -fcilkplus -dynamiclib -o hello.dylib hello.c
-lcilkrts **/
#include <stdio.h> #include <cilk/cilk.h> #include <unistd.h> void
hello(int n) { int i; cilk_for (i=1; i <= n; i++ ) { sleep(1.0);
printf("hello %d\n",i); } }
I'm on a Mac (10.11) running Julia 0.4.3, PyPlot 2.1.1, and gcc 5.3.0
(macports). My installation of PyPlot has been working just fine except for
this particular issue.
Also, if I change the "cilk_for" in hello.c to "for" (but still link
libcilkrts) then PyPlot would load and work just fine.
Any idea what's going on? I'm not sure this is a problem with Julia or
PyPlot per se, but don't know enough about the ffi, the cilk runtime, or
PyPlot/PyCall internals to figure this out.
Thanks for any pointers!
KL
