[Numpy-discussion] numpy/Windows shared arrays between processes?
Ray S
subscriber100 at rjs.org
Tue Oct 9 17:32:45 EDT 2007
On 10/9/07, Sebastian Haase replied:
> > Did you find that locks
> > or semaphores were needed?
> Maybe that's why it crashed ;-) !? But for simple use it seems
fine.
I just did some code (below) that does read/write to the array AFAP,
and there is no crash, or any other issue (Win2000, py2.4, numpy
1.0b1).
Without the print statements, it does max both processors; with
printing I/O only 58%.
Both processes can modify the array without issue either.
I'll experiment with
I had seen the Win mmap in this thread:
http://objectmix.com/python/127666-shared-memory-pointer.html
and here:
http://www.codeproject.com/cpp/embedpython_2.asp
Note also that the Python mmap docs read "In either case you must
provide a file descriptor for a file opened for update." and no
mention of the integer zero descriptor option.
Access options behave as presented.
Because *NIX has MAP_SHARED as an option you'd think that there might
be cross-platform share behavior with some platform checking if
statements. Without a tag though, how does another process reference
the same memory on NIX, a filename? (It seems)
> > But I had the same
> > issue as Mark Heslep
> >
http://aspn.activestate.com/ASPN/Mail/Message/ctypes-users/3192422
> > of creating a numpy array from a raw address (not a c_array).
>I assume this is a different issue, but haven't looked into it yet.
Yes, a different methodology attempt. It would be interesting to know
anyway how to create a numpy array from an address; it's probably
buried in the undocumented C-API that I don't grok, and likely
frowned upon.
Thanks,
Ray
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