# numpyShared.py
import numpy as N
def arrSharedMemory(shape, dtype, tag="PySharedMemory", access=None):
"""
Windows only !
share memory between different processes if same `tag` is used.
"""
itemsize = N.dtype(dtype).itemsize
count = N.product(shape)
size = count * itemsize
import mmap
sharedmem = mmap.mmap(0, size, tag, access)
a=N.frombuffer(sharedmem, dtype, count)
a.shape = shape
return a
if __name__ == '__main__':
## test it
## produce a mish-mash of output on one shell screen
import random
import time
import subprocess, sys
import mmap
if len(sys.argv)<2:
pid = subprocess.Popen([r'C:\python24\python.exe',
['numpyShared.py rjs100']]).pid
## the parent process
a1 = arrSharedMemory((10000,), N.int32, tag='rjs100',
access=mmap.ACCESS_WRITE)
time.sleep(.7)
now=time.time();
while time.time()<now+3:
tmp = a1[0]**.5
a1[0]=random.random()*10
#print '\np%d' % a1[0]
else:
tag = sys.argv[0][1]
a2 = arrSharedMemory((10000,), N.int32, tag='rjs100',
access=mmap.ACCESS_READ)
now=time.time()
while time.time()<now+3:
tmp = a2[0]**.5
#print '\nc%d' % a2[0]
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