Re: Session file locking not working properly in multithreaded environment

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Ralph Heinkel wrote:
> I'm not completely convinced that this is true. Here is an example=20
> where a second lock on the same file fails within the same thread:
> ...
> Only if lock2 was obtained from fp1.fileno() then no exception would=20
> have been raised. As soon as a separate file descriptor (for the same=20
> file) is used a second lock also fails.
> But this is exaclty the point that makes me wonder why it then works=20
> in cherrypy. From the log you can see that each thread uses a=20
> different file descriptor for the lock file, so it should fail there=20
> as well...=C2=A0 I'm still puzzled.

Yes, you're right.=C2=A0 The behavior I described is only true if you try t=
o=20
flock the same file descriptor, or file descriptors that are "dup"s of=20
each other.=C2=A0 If the file descriptors came from two separate opens, the=
n=20
the flock should work.

The zc.lockfile I'm looking at certainly opens a new fd each time, but=20
the source I'm looking at doesn't have a UnixLockFile class, as your log=20
shows.

Your log shows to calls to _lock_file, but it doesn't show that the both=20
succeed.=C2=A0 Do they?

--=20
Tim Roberts, [email protected]
Providenza & Boekelheide, Inc.


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