using mmap on large (> 2 Gig) files

"Martin v. Löwis" martin at
Tue Oct 24 19:31:45 CEST 2006

sturlamolden schrieb:
> Looking at Python's source (mmapmodule.c), it seems that "mmap.mmap"
> always sets the offset argument in Windows MapViewOfFile and UNIX to 0.
> This means that it is always mapping from the beginning of the file.
> Thus, Python's mmap module is useless for large files. This is really
> bad coding. The one that wrote mmapmodule.c didn't consider the
> posibility that a 64 bit file system like NTFS can harbour files to
> large to fit in a 32 address space. Thus,
> mmapmodule.c needs to be fixed before it can be used for large files.

You know this isn't true in general. It is true for a 32-bit address
space only.


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