[SciPy-dev] huge speed regression in loadmat from 0.6.0 to 0.7.0
Scott David Daniels
Fri Feb 13 15:24:55 CST 2009
My former follow-up bounced, so just to close the loop:
Ryan May wrote:
> ... <places bag over head> I can't believe I didn't notice you weren't
> the OP. And yeah, I forgot the loop control. Clearly, this is
> evidence that I shouldn't start my day with creating a patch, though I
> did at least have the sense to run the test suite. Obviously, the
> tests don't exercise a code path that uses the len(self.data) < bytes.
Actually this issue is hard to hard to test as a black box, since
over-filling should work correctly but inefficiently.
> As far as bytes goes, it isn't initialized to -1, but rather
> read_to_end is a boolean set to the value of (bytes == -1), so
> that you can pass bytes in as -1 and read all the data.
Right. I figured that out when I actually went back to the original to
make a patch. Many eyes make bugs shallow. There is one thing I did
that you might want to incorporate:
self_data = 
self_data = [self.data]
And then at the bottom, instead of:
self.data += ''.join([self_data])
self.data = ''.join([self_data])
This way, the full length of the result is know before combining
anything (so you get a single large buffer allocation, rather than two).
--Scott David Daniels
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