IPC::Sharable

[Peteris Krumins]

To keep statistics which are collected by
parent and child processes I decided to
take the advantage of shared memory (shm) and
share some variables (scalars and hashes).

The parent forks lots of child processes (depending
on load 100 to 1000 an hour), which
increase some counters and create hash data structures.

The problem is that after couple of hours looking
at `ipcs' output I see no shm is released, new memory
is allocated and the list grows larger and larger.
I am afraid to run out of memory.
Once an hour the program received USR1 signal
upon which it dumps the statistics to a file and
(imo) frees memory.

the program structure is like following:

my %stats;
my $stats_handle;
my $stats_handle_chkd;
my $stats_handle_rej;
my ($stats_rcvd, $stats_chkd, $stats_rej);

# ...
# make variables shared
#

$stats_handle_chkd = tie $stats_chkd, 'IPC::Shareable',
undef, { destroy => 1 };
$stats_handle_rej = tie $stats_rej, 'IPC::Shareable',
undef, { destroy => 1 };
$stats_handle = tie %stats, 'IPC::Shareable',
undef, { destroy => 1 };
($stats_rcvd, $stats_chkd, $stats_rej) = (0,0,0);

# ...
# loop until <something> {
# ...

$stats_rcvd++;

# ...

fork

here increase $stats_chkd, $stats_rej,
and do smth with hash, for example
$stats{'in'}{'user_one'}++;

exit child

# }

# and the signal USR1 handler just:
#
sub usr1_handler {
# dump data to file
# ...

($stats_rcvd, $stats_chkd, $stats_rej) = (0,0,0);
%stats = ();
}


P.Krumins