create table foolock ( /* since we're exclusive per-program, make program primary */ program varchar(64) primary key, client varchar(255) not null, time timestamp ); #### #!/usr/bin/perl use strict; use warnings; use File::Basename; use Sys::Hostname; use DBI; my $dbh = DBI->connect('dbi:mysql:test:host','foolocker','foopass',{RaiseError=>1}); my $lock_interval = 10; # minimum wait in milliseconds between attempts my $max_attempts = 5; # maximum number of attempts sub prog_client { ((basename $0), hostname.":$$"); } sub get_lock { sql_lock('insert into foolock (program, client) values (?,?)', prog_client); } sub finish_up { sql_lock('delete from foolock where program = ? and client = ?', prog_client); } sub sql_lock { my ($sql, @params) = @_; my $lock = $dbh->prepare_cached($sql); my $backoff = $lock_interval / 1000; for (1..$max_attempts) { my $got = eval { $dbh->do('lock tables foolock write'); $lock->execute(@params) >= 0; }; $dbh->do('unlock tables'); return 1 if $got; select undef, undef, undef, $backoff; $backoff *= 2; } return 0; } if (get_lock) { # do your thing finish_up; } else { # take appropriate action }