File locking using fcntl.flock()

[Donn Cave]

Quoth Richard Jones <rjones at ekit-inc.com>:
| On Wed, 17 Apr 2002 03:38, Donn Cave wrote:
...
| > I don't have Solaris, but I bet it doesn't have flock.
|
| It does, under the heading of "BSD compatibility".

For python, that would make 2 questions:  1) was python built with
the BSD compatibility, and 2) is flock() a bona fide implementation
or does it call fcntl.  The answer to one or both is apparently "no",
or you'd get flock semantics.

| That's almost a moot point though, because I also mentioned that I tried both 
| fcntl.lockf() ("This is essentially a wrapper around the fcntl() locking 
| calls.") and posixfile.lock() and neither of those worked either. The _real_ 
| problem here is that Solaris appears to allow a process to have two locks on 
| a single file in the same process. Things are fine if the lock is requested 
| from separate processes.

I think I explained this.  It isn't just Solaris.  Those functions will
have the same semantics on NetBSD etc.

| Thus in separate processes fcntl.lockf() and friends work fine. This is 
| troublesome because threads can't use file locks. Just gotta avoid threading 

That's a good idea in general, anyway.

	Donn Cave, donn at u.washington.edu