🚀 go-pugleaf

Submitted-by: henry@zoo.toronto.edu (Henry Spencer)

>Submitted-by: johnl@iecc.cambridge.ma.us (John R. Levine)
>The time-honored technique of using a directory as a semaphore and using
>mkdir() and rmdir() as lock and unlock works fairly well, although it's
>rather slow...

It isn't reliable, however.  The crucial point is that NFS does not provide
a sufficiently good imitation of Unix filesystem semantics.  I'm told -- I
have not seen details and don't have a reference -- that if you look hard
enough at the problem, and consider things like finite cache sizes, you
can prove that there is *no way* to do reliable locking through the NFS
protocol.  You have to use some sort of non-filesystem method, like
locking daemons (and I agree with John that writing your own is the best
method; the existing ones are garbage).

This is one reason (of many) why proposals to canonize NFS as a standard
weren't greeted with cries of delight from all directions...
-- 
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  henry@zoo.toronto.edu  utzoo!henry


Volume-Number: Volume 29, Number 30