creating/modifying sparse files on linux

[Trent Mick]

[draghuram at gmail.com wrote]
> 
> Hi,
> 
> Is there any special support for sparse file handling in python? My
> initial search didn't bring up much (not a thorough search). I wrote
> the following pice of code:
> 
> options.size = 6442450944
> options.ranges = ["4096,1024","30000,314572800"]
> fd = open("testfile", "w")
> fd.seek(options.size-1)
> fd.write("a")
> for drange in options.ranges:
>     off = int(drange.split(",")[0])
>     len = int(drange.split(",")[1])
>     print "off =", off, " len =", len
>     fd.seek(off)
>     for x in range(len):
>     fd.write("a")
> 
> fd.close()
> 
> This piece of code takes very long time and in fact I had to kill it as
> the linux system started doing lot of swapping. Am I doing something
> wrong here? Is there a better way to create/modify sparse files?

test_largefile.py in the Python test suite does this kind of thing and
doesn't take very long for me to run on Linux (SuSE 9.0 box).

Trent

-- 
Trent Mick
TrentM at ActiveState.com