On Aug 7, 2008, at 12:36 AM, Ian Charnas wrote:
Hello heroes and heroins of the python universe, lend me your ears and
I will tell you a tale that will make your platters spin!
As noted by SQLite [1] and MySQL [2] developers, fsync on OS X does
not actually flush a file to disk... instead OS X provides "fullfsync"
which actually flushes the file descriptor to disk. This simple patch
modifies python's "fsync" to take advantage of fullfsync on platforms
that support it:
http://bugs.python.org/issue3512
While some people might suggest that fullfsync should be exposed as a
method on the 'os' module for platforms that support it, I believe
this is not the best approach. Because the docstring for os.fsync
says that it forces the file to be written to disk, I think it's up to
python to ensure that functionality is really there on all platforms.
Currently on OS X, fullfsync is needed to provide this functionality,
so I think python's os.fsync should use fullfsync on OS X.
Please don't make that change. fsync on OSX does the same thing as
fsync traditionally does on other OSes. That is: it flushes the data
to "disk", but doesn't make any effort to ensure that the disk drive
actually flushes the data from its own write cache to the platter.
Other OSes just don't expose that functionality *at all*.
See e.g. this thread:
http://lists.apple.com/archives/Darwin-dev/2005/Feb/msg00072.html
You should instead propose a patch to add F_FULLSYNC to the fcntl
module when present.
James
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