NAME¶
Parallel::Runner - An object to manage running things in parallel processes.
DESCRIPTION¶
There are several other modules to do this, you probably want one of them. This
module exists as a super specialised parallel task manager. You create the
object with a process limit and callbacks for what to do while waiting for a
free process slot, as well as a callback for what a process should do just
before exiting.
You must explicitly call $runner->
finish() when you are done. If the
runner is destroyed before it's children are finished a warning will be
generated and your child processes will be killed, by force if necessary.
If you specify a maximum of 1 then no forking will occur, and
run() will
block until the coderef returns. You can force a fork by providing a boolean
true value as the second argument to
run(), this will force the runner
to fork before running the coderef, however
run() will still block
until it the child exits.
SYNOPSYS¶
#!/usr/bin/perl
use strict;
use warnings;
use Parallel::Runner;
my $runner = Parallel::Runner->new(4);
$runner->run( sub { ... } );
$runner->run( sub { ... } );
$runner->run( sub { ... } );
$runner->run( sub { ... } );
# This will block until one of the previous 4 finishes
$runner->run( sub { ... } );
# Do not forget this.
$runner->finish;
CONSTRUCTOR¶
- $runner = $class->new( $max, $accessor => $value, ... );
- Create a new instance of Parallel::Runner. $accessor can be anything
listed under the ACCESSORS section. $max should be the maximum number of
processes allowed, defaults to 1.
ACCESSORS¶
These are simple accessors, provididng an argument sets the accessor to that
argument, no argument it simply returns the current value.
- $val = $runner->data_callback( \&callback )
- If this is specified than IPC will be automatically enabled, and the final
return from each process will be passed into this handler in the main
process. Due to the way IPC works only strings/numerical data is passed,
if you need to pass a ref you will need to serialize it yourself before
returning it, followed by deserializing it in your callback.
Example:
# Place to put the accumulated data
my @accum_data;
# Create the runner with a callback that pushes the data onto our array.
$runner = $CLASS->new( 2,
data_callback => sub {
my ($data) = @_;
push @accum_data => $data;
},
);
# 4 processes that return data
$runner->run( sub { return "foo" });
$runner->run( sub { return "bar" });
$runner->run( sub { return "baz" });
$runner->run( sub { return "bat" });
$runner->finish;
# Verify the data (order is not predictable)
is_deeply(
[ sort @accum_data ],
[ sort qw/foo bar baz bat/ ],
"Got all data returned by subprocesses"
);
- $val = $runner->exit_callback( \&callback )
- Codref to call just before a child exits (called within child)
- $val = $runner->iteration_delay( $float );
- How long to wait per iterate if nothing has changed.
- $val = $runner->iteration_callback( $newval )
- Coderef to call multiple times in a loop while run() is blocking
waiting for a process slot.
- $val = $runner->reap_callback( $newval )
- Codref to call whenever a pid is reaped using waitpid. The callback sub
will be passed 3 values The first is the exit status of the child process.
The second is the pid of the child process. The third used to be the
return of waitpid, but this is depricated as Child is now used and throws
an exception when waitpid is not what it should be. The third is simply
the pid of the child process again. The final argument is the child
process object itself.
$runner->reap_callback( sub {
my ( $status, $pid, $pid_again, $proc ) = @_;
# Status as returned from system, so 0 is good, 1+ is bad.
die "Child $pid did not exit 0"
if $status;
});
- @children = $runner->children( @append )
- Returns a list of Child::Link::Proc objects.
- $val = $runner->pid()
- pid of the parent process
- $val = $runner->max( $newval )
- Maximum number of children
OBJECT METHODS¶
- run( $code )
- run( $code, $force_fork )
- Run the specified code in a child process. Blocks if no free slots are
available. Force fork can be used to force a fork when max is 1, however
it will still block until the child exits.
- finish()
- finish( $timeout )
- finish( $timeout, $timeoutcallback )
- Wait for all children to finish, then clean up after them. If a timeout is
specified it will return after the timeout regardless of wether or not
children have all exited. If there is a timeout call back then that code
will be run upon timeout just before the method returns.
NOTE: DO NOT LET YOUR RUNNER BE DESTROYED BEFORE FINISH COMPLETES WITHOUT A
TIMEOUT.
the runner will kill all children, possibly with force if your runner is
destroyed with children still running, or not waited on.
- killall( $sig )
- Send all children the specified kill signal.
- DESTROY()
- Automagically called when the object is destroyed. If called while
children are running it will forcefully clean up after you as follows:
1) Sends an ugly warning.
2) Will first give all your children 1 second to complete.
Windows) Strawberry fails with processes, so on windows DESTROY will wait as
long as needed, possibly forever.
3) Sends kill signal 15 to all children then waits up to 4 seconds.
4) Sends kill signal 9 to any remaining children then waits up to 10 seconds
5) Gives up and returns
FENNEC PROJECT¶
This module is part of the Fennec project. See Fennec for more details. Fennec
is a project to develop an extendable and powerful testing framework. Together
the tools that make up the Fennec framework provide a potent testing
environment.
The tools provided by Fennec are also useful on their own. Sometimes a tool
created for Fennec is useful outside the greator framework. Such tools are
turned into their own projects. This is one such project.
- Fennec - The core framework
- The primary Fennec project that ties them all together.
AUTHORS¶
Chad Granum exodist7@gmail.com
COPYRIGHT¶
Copyright (C) 2010 Chad Granum
Parallel-Runner is free software; Standard perl licence.
Parallel-Runner is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the license for more details.