[Python-Dev] Python-Dev] wait time [was: Ext4 data loss

[Steven D'Aprano]

On Fri, 13 Mar 2009 01:02:26 pm R. David Murray wrote:
> On Fri, 13 Mar 2009 at 00:35, Antoine Pitrou wrote:
> > R. David Murray <rdmurray <at> bitdance.com> writes:
> >> Seriously, though, the point is that IMO an application should not
> >> be calling fsync unless it provides a way for that behavior to be
> >> controlled by the user.
> >
> > But whether an application does it or not is none of Python's
> > business, is it? What is the disagreement exactly?
>
> I'd like to see whatever feature gets added support the application
> writer in making this user controllable, or at the very least
> document that this to do so is best practice if you use the sync
> feature.

It's not best practice. It may be best practice for a certain class of 
users and applications, e.g. those who value the ability to control 
low-level behaviour of the app, but it is poor practice for other 
classes of users and applications. Do you really think that having 
Minefield make the file syncing behaviour of the high scores file 
user-configurable is best practice? People care about their high 
scores, but they don't care that much.

It may even lead to more data loss than leaving it out:

* If the application chooses a specific strategy, this strategy might 
(for the sake of the argument) lead to data loss once in ten million 
writes on average.

* If the application makes this a configuration option, the increased 
complexity of writing the code, and the increased number of paths that 
need to be tested, may lead to bugs which cause data loss. This may be 
more risky than the original strategy above (whatever that happens to 
be.)

Complexity is not cost-free, and insisting that the more complex, 
expensive solution is always "best practice" is wrong.


-- 
Steven D'Aprano