Provided by: libmce-perl_1.879-1_all 
NAME
MCE - Many-Core Engine for Perl providing parallel processing capabilities
VERSION
This document describes MCE version 1.879
Many-Core Engine (MCE) for Perl helps enable a new level of performance by maximizing all
available cores.
DESCRIPTION
MCE spawns a pool of workers and therefore does not fork a new process per each element of
data. Instead, MCE follows a bank queuing model. Imagine the line being the data and bank-
tellers the parallel workers. MCE enhances that model by adding the ability to chunk the
next n elements from the input stream to the next available worker.
SYNOPSIS
This is a simplistic use case of MCE running with 5 workers.
# Construction using the Core API
use MCE;
my $mce = MCE->new(
max_workers => 5,
user_func => sub {
my ($mce) = @_;
$mce->say("Hello from " . $mce->wid);
}
);
$mce->run;
# Construction using a MCE model
use MCE::Flow max_workers => 5;
mce_flow sub {
my ($mce) = @_;
MCE->say("Hello from " . MCE->wid);
};
The following is a demonstration for parsing a huge log file in parallel.
use MCE::Loop;
MCE::Loop->init( max_workers => 8, use_slurpio => 1 );
my $pattern = 'something';
my $hugefile = 'very_huge.file';
my @result = mce_loop_f {
my ($mce, $slurp_ref, $chunk_id) = @_;
# Quickly determine if a match is found.
# Process the slurped chunk only if true.
if ($$slurp_ref =~ /$pattern/m) {
my @matches;
# The following is fast on Unix, but performance degrades
# drastically on Windows beyond 4 workers.
open my $MEM_FH, '<', $slurp_ref;
binmode $MEM_FH, ':raw';
while (<$MEM_FH>) { push @matches, $_ if (/$pattern/); }
close $MEM_FH;
# Therefore, use the following construction on Windows.
while ( $$slurp_ref =~ /([^\n]+\n)/mg ) {
my $line = $1; # save $1 to not lose the value
push @matches, $line if ($line =~ /$pattern/);
}
# Gather matched lines.
MCE->gather(@matches);
}
} $hugefile;
print join('', @result);
The next demonstration loops through a sequence of numbers with MCE::Flow.
use MCE::Flow;
my $N = shift || 4_000_000;
sub compute_pi {
my ( $beg_seq, $end_seq ) = @_;
my ( $pi, $t ) = ( 0.0 );
foreach my $i ( $beg_seq .. $end_seq ) {
$t = ( $i + 0.5 ) / $N;
$pi += 4.0 / ( 1.0 + $t * $t );
}
MCE->gather( $pi );
}
# Compute bounds only, workers receive [ begin, end ] values
MCE::Flow->init(
chunk_size => 200_000,
max_workers => 8,
bounds_only => 1
);
my @ret = mce_flow_s sub {
compute_pi( $_->[0], $_->[1] );
}, 0, $N - 1;
my $pi = 0.0; $pi += $_ for @ret;
printf "pi = %0.13f\n", $pi / $N; # 3.1415926535898
CORE MODULES
Four modules make up the core engine for MCE.
MCE::Core
This is the POD documentation describing the core Many-Core Engine (MCE) API. Go here
for help with the various MCE options. See also, MCE::Examples for additional
demonstrations.
MCE::Mutex
Provides a simple semaphore implementation supporting threads and processes. Two
implementations are provided; one via pipes or socket depending on the platform and the
other using Fcntl.
MCE::Signal
Provides signal handling, temporary directory creation, and cleanup for MCE.
MCE::Util
Provides utility functions for MCE.
MCE EXTRAS
There are 5 add-on modules for use with MCE.
MCE::Candy
Provides a collection of sugar methods and output iterators for preserving output
order.
MCE::Channel
Introduced in MCE 1.839, provides queue-like and two-way communication capability.
Three implementations "Simple", "Mutex", and "Threads" are provided. "Simple" does not
involve locking whereas "Mutex" and "Threads" do locking transparently using
"MCE::Mutex" and "threads" respectively.
MCE::Child
Also introduced in MCE 1.839, provides a threads-like parallelization module that is
compatible with Perl 5.8. It is a fork of MCE::Hobo. The difference is using a common
"MCE::Channel" object when yielding and joining.
MCE::Queue
Provides a hybrid queuing implementation for MCE supporting normal queues and priority
queues from a single module. MCE::Queue exchanges data via the core engine to enable
queuing to work for both children (spawned from fork) and threads.
MCE::Relay
Provides workers the ability to receive and pass information orderly with zero
involvement by the manager process. This module is loaded automatically by MCE when
specifying the "init_relay" MCE option.
MCE MODELS
The MCE models are sugar syntax on top of the MCE::Core API. Two MCE options (chunk_size
and max_workers) are configured automatically. Moreover, spawning workers and later
shutdown occur transparently behind the scene.
Choosing a MCE Model largely depends on the application. It all boils down to how much
automation you need MCE to handle transparently. Or if you prefer, constructing the MCE
object and running using the core MCE API is fine too.
MCE::Grep
Provides a parallel grep implementation similar to the native grep function.
MCE::Map
Provides a parallel map implementation similar to the native map function.
MCE::Loop
Provides a parallel for loop implementation.
MCE::Flow
Like "MCE::Loop", but with support for multiple pools of workers. The pool of workers
are configured transparently via the MCE "user_tasks" option.
MCE::Step
Like "MCE::Flow", but adds a "MCE::Queue" object between each pool of workers. This
model, introduced in 1.506, allows one to pass data forward (left to right) from one
sub-task into another with little effort.
MCE::Stream
This provides an efficient parallel implementation for chaining multiple maps and greps
transparently. Like "MCE::Flow" and "MCE::Step", it too supports multiple pools of
workers. The distinction is that "MCE::Stream" passes data from right to left and done
for you transparently.
MISCELLANEOUS
Miscellaneous additions included with the distribution.
MCE::Examples
Describes various demonstrations for MCE including a Monte Carlo simulation.
MCE::Subs
Exports functions mapped directly to MCE methods; e.g. mce_wid. The module allows 3
options; :manager, :worker, and :getter.
REQUIREMENTS
Perl 5.8.0 or later.
SOURCE AND FURTHER READING
The source and examples are hosted at GitHub.
• <https://github.com/marioroy/mce-perl>
• <https://github.com/marioroy/mce-examples>
SEE ALSO
Refer to the MCE::Core documentation where the API is described.
"MCE::Shared" provides data sharing capabilities for "MCE". It includes "MCE::Hobo" for
running code asynchronously with the IPC handled by the shared-manager process.
• MCE::Shared
• MCE::Hobo
AUTHOR
Mario E. Roy, <marioeroy AT gmail DOT com>
COPYRIGHT AND LICENSE
Copyright (C) 2012-2022 by Mario E. Roy
MCE is released under the same license as Perl.
See <https://dev.perl.org/licenses/> for more information.