[ python-Bugs-1586414 ] tarfile.extract() may cause file fragmentation on Windows XP

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Bugs item #1586414, was opened at 2006-10-28 23:22
Message generated for change (Settings changed) made by gustaebel
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Category: Python Library
Group: Python 2.4
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Enoch Julias (enochjul)
>Assigned to: Lars Gustäbel (gustaebel)
Summary: tarfile.extract() may cause file fragmentation on Windows XP

Initial Comment:
When I use tarfile.extract() to extract all the files
from a large tar archive with lots of files tends to
cause file fragmentation in Windows. Apparently NTFS
cluster allocation interacts badly with such operations
if Windows is not aware of the size of each file.

The solution is to use a combination of the Win32 APIs
SetFilePointer() and SetEndOfFile() before writing to
the target file. This helps Windows choose a contiguous
free space for the file.

I tried it on the 2.6 trunk by calling file.truncate()
(which seems to implement the appropriate calls on
Windows) to set the file size before writing to a file.
It helps to avoid fragmentation for the extracted files
on my Windows XP x64 system.

Can this be added to tarfile to improve its performance
on Windows?

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Comment By: Enoch Julias (enochjul)
Date: 2006-10-31 06:07

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I submitted patch #1587674 for this, though I am not sure if
it is a good idea to use truncate() for such a purpose.

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Comment By: Georg Brandl (gbrandl)
Date: 2006-10-29 09:55

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Can you try to come up with a patch?

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