NAME

       Parallel::Prefork - A simple prefork server framework

SYNOPSIS

         use Parallel::Prefork;

         my $pm = Parallel::Prefork->new({
           max_workers  => 10,
           trap_signals => {
             TERM => 'TERM',
             HUP  => 'TERM',
             USR1 => undef,
           }
         });

         while ($pm->signal_received ne 'TERM') {
           load_config();
           $pm->start(sub {
               ... do some work within the child process ...
           });
         }

         $pm->wait_all_children();

DESCRIPTION

       "Parallel::Prefork" is much like "Parallel::ForkManager", but supports graceful shutdown
       and run-time reconfiguration.

METHODS

   new
       instantiation.  Takes a hashref as an argument.  Recognized attributes are as follows.

       max_workers

       number of worker processes (default: 10)

       spawn_interval

       interval in seconds between spawning child processes unless a child process exits
       abnormally (default: 0)

       err_respawn_interval

       number of seconds to deter spawning of child processes after a worker exits abnormally
       (default: 1)

       trap_signals

       hashref of signals to be trapped.  Manager process will trap the signals listed in the
       keys of the hash, and send the signal specified in the associated value (if any) to all
       worker processes.  If the associated value is a scalar then it is treated as the name of
       the signal to be sent immediately to all the worker processes.  If the value is an
       arrayref the first value is treated the name of the signal and the second value is treated
       as the interval (in seconds) between sending the signal to each worker process.

       on_child_reap

       coderef that is called when a child is reaped. Receives the instance to the current
       Parallel::Prefork, the child's pid, and its exit status.

       before_fork

       after_fork

       coderefs that are called in the manager process before and after fork, if being set

   start
       The main routine.  There are two ways to use the function.

       If given a subref as an argument, forks child processes and executes that subref within
       the child processes.  The processes will exit with 0 status when the subref returns.

       The other way is to not give any arguments to the function.  The function returns undef in
       child processes.  Caller should execute the application logic and then call "finish" to
       terminate the process.

       The "start" function returns true within manager process upon receiving a signal specified
       in the "trap_signals" hashref.

   finish
       Child processes (when executed by a zero-argument call to "start") should call this
       function for termination.  Takes exit code as an optional argument.  Only usable from
       child processes.

   signal_all_children
       Sends signal to all worker processes.  Only usable from manager process.

   wait_all_children()
   wait_all_children($timeout)
       Waits until all worker processes exit or timeout (given as an optional argument in
       seconds) exceeds.  The method returns the number of the worker processes still running.

AUTHOR

       Kazuho Oku

LICENSE

       This program is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself.

       See http://www.perl.com/perl/misc/Artistic.html