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lib/Apache/Session/Lock/Semaphore.pm  view on Meta::CPAN

Apache::Session::Lock::semaphore fulfills the locking interface of 
Apache::Session.  Mutual exclusion is achieved through system semaphores and
the IPC::Semaphore module.

=head1 CONFIGURATION

The module must know how many semaphores to use, and what semaphore key to
use. The number of semaphores has an impact on performance.  More semaphores
means less lock contention. You should use the maximum number of semaphores
that your platform will allow. On stock NetBSD, OpenBSD, and Solaris systems,
this is probably 16. On Linux 2.2, this is 32. This module tries to guess
the number based on your operating system, but it is safer to configure it
yourself.

To set the number of semaphores, you need to pass an argument in the usual
Apache::Session style. The name of the argument is NSems, and the value is
an integer power of 2. For example:

 tie %s, 'Apache::Session::Blah', $id, {NSems => 16};

You may also need to configure the semaphore key that this package uses. By