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Re: Change default MTA was Re: Fedora Core 2 wishlists



On Wed, 10 Dec 2003, Sam Varshavchik wrote:

> Chris Ricker writes:
> 
> > On Wed, 10 Dec 2003, Ronny Buchmann wrote:
> > 
> >> If MDA and MUA try to access it at the same time, you run into problems when 
> >> they don't agree on a locking scheme or when using NFS.
> >> 
> >> Maildirs don't need locking.
> > 
> > Not true. That's why what passes for the Maildir standard was revised 
> > earlier this year, after people found out the hard way that the "locking 
> > not needed" hype was losing their email....
> 
> I'm not aware of Bernstein doing anything like that.
> 
> If you're referring to adding milliseconds to the filename, nothing in the 
> revised naming convention requires any kind of locking whatsoever.  I'm not 
> sure where that notion came from.  Sounds like the usual suspects have been 
> spraying FUD again.

I'm not saying it required locking, I'm saying one reason the revision was
needed was due to lack of locking. Look at why the file naming was revised
-- PID recycling was causing non-unique filenames w/in a second, which in
turn lead to collisions. One way of looking at that is that the original
Maildir convention was fine to still use with locking as protection against
concurrency. The other way of looking at it is that the original standard
was broken and truly unique filenames should have been chosen instead. As it
happens, djb changed the standard (though I don't think qmail got
updated?)....

Similarly, what can happen when you mix products which implement Maildirs
differently (ie, Postfix LDA does something like time.device#inode#.hostname
now, while Mutt appears to still do something more like time.pid.hostname
for the uniqueness in filenames)? Shouldn't locking be needed there?

later,
chris




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