=head1 NAME

Preventive Measures for Performance Enhancement

=head1 Description

This chapter explains what should or should not be done in order to
keep the performance high

=head1 Memory Leakage

L<Memory leakage in 1.0 docs|docs::1.0::guide::performance/Memory_leakage>.

=head2 Proper Memory Pools Usage

Several mod_perl 2.0 APIs are using Apache memory pools for memory
management. Mainly because the underlying C API requires that. So
every time Apache needs to allocate memory it allocates it using the
pool object that is passed as an argument. Apache doesn't frees
allocated memory, this happens automatically when a pool ends its
life.

Different pools have different life lengths. Request pools
(C<$r-E<gt>pool>) are destroyed at the end of each request. Connection
pools (C<$c-E<gt>pool>) are destroyed when the connection is
closed. Server pools C<$s-E<gt>pool>) and the global pools (accessible
in the server startup phases, like C<PerlOpenLogsHandler> handlers)
are destroyed only when the server exits.

Therefore always use the pool of the shortest possible life if you
can. Never use server pools during request, when you can use a request
pool. For example inside an HTTP handler, don't call:

  my $dir = Apache2::ServerUtil::server_root_relative($s->process->pool, 'conf');

when you should call:

  my $dir = Apache2::ServerUtil::server_root_relative($r->pool, 'conf');

Of course on special occasions, you may want to have something
allocated off the server pool if you want the allocated memory to
survive through several subsequent requests or connections. But this
is normally doesn't apply to the core mod_perl 2.0, but rather for 3rd
party extensions.


=head1 Maintainers

Maintainer is the person(s) you should contact with updates,
corrections and patches.

=over

=item *

Stas Bekman E<lt>stas (at) stason.orgE<gt>

=back

=head1 Authors

=over

=item *

Stas Bekman E<lt>stas (at) stason.orgE<gt>

=back

Only the major authors are listed above. For contributors see the
Changes file.

=cut
