cPickle.load vs. file.read+cPickle.loads on large binary files
andrea.gavana at gmail.com
andrea.gavana at gmail.com
Wed Nov 18 05:31:34 EST 2015
Hi,
On Wednesday, November 18, 2015 at 10:00:43 AM UTC+1, Nagy László Zsolt wrote:
> > Perhaps there is a size threshold? You could experiment with different block
> > sizes in the following f.read() replacement:
> >
> > def read_chunked(f, size=2**20):
> > read = functools.partial(f.read, size)
> > return "".join(iter(read, ""))
> >
> Under win32 platform, my experience is that the fastest way to read
> binary file from disk is the mmap module. You should try that too.
Thank you for your suggestion. I have tried that now, and with my naive approach I have done this:
start = time.time()
fid = open(filename, 'r+b')
strs = mmap.mmap(fid.fileno(), 0, access=mmap.ACCESS_READ)[:]
end = time.time()
print 'mmap.read time:', end-start
And it takes about 2.7 seconds. Not a bad improvement :-) . Unfortunately, when the file is on a network drive, all the other approaches ran at around 25-30 seconds loading time, while the mmap one clocks at 110 seconds :-(
Andrea.
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