#11158: get_image_dimensions very slow after 1 call
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Reporter: kua | Owner: nobody
Status: new | Milestone:
Component: Uncategorized | Version: 1.0
Keywords: get_image_dimensions, field, save, slow | Stage: Unreviewed
Has_patch: 1 |
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get_image_dimensions in django.core.files.images is very slow after 1 call
This has the effect of slowing down calls to save on model image fields,
the whole thing shudders to a halt while we spin around in PIL.Image.feed
The issue is that the read pointer is not being reset after the call to
get_image_dimensions. Subsequent calls to file.read
To reproduce:
from django.core.files.images import get_image_dimensions[[BR]]
from django.core.files.uploadedfile import File[[BR]]
f = File(open('/tmp/some_multi_megabyte_file.jpg')[[BR]]
get_image_dimensions(f)[[BR]]
get_image_dimensions(f)[[BR]]
I suggest this function should save the read pointer pos, reset it to 0,
then do all the PIL fancyness, then reset the pointer when finished. I've
tried to attach a patch that reflects this
Imagine this scenario: Someone mucks with the read pointer on a hundred
meg image, say reads 2 kilobytes. Then this function is called and starts
reading data in 1K chunks looking for a header (which has already been
skipped).
So 100 Megabytes - 2 kilobytes / 1024 bytes per read means this function
will be called over 100,000 times
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Ticket URL: <http://code.djangoproject.com/ticket/11158>
Django <http://code.djangoproject.com/>
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