On 06/09/2013 05:40 PM, Ric Wheeler wrote:
On 06/09/2013 04:06 PM, Steve Bergman wrote:
[...]
a quick find/fgrep doesn't reveal any usage of fsync at all in any of
the ".py" files which ship with the distro. Perhaps the Python VM
invokes it automatically? Strace says no. And this is in an enterprise
distro which clearly states in its Administrator Manual sections on
Ext4 & XFS that you *must* use fsync to avoid losing data. I haven't
checked Ruby or Perl, but I think it's a pretty good guess that I'd
find the same thing.
I don't know any details about Python, Ruby or Perl internals, but will
poke around. Note that some of the standard libraries they call might
also have buried calls in them to do the write thing with fsync() or
fdatasync().
Perl's IO layer is tunable using various "personalities" you can invoke
at module load, file open, on file descriptors, etc. The syncs are in
the standard library. This said, a number of the distro Perl's are
badly horribly broken (or out of date and EOLed for years now ... cough
cough). Python has similar capability, and its IO layer is usually a
direct pass through to the underlying library calls. You can force sync
on IO, though most sane programmers won't do that.
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