NAME
MCE::Hobo - A threads-like parallelization module
VERSION
This document describes MCE::Hobo version 1.008
SYNOPSIS
use MCE::Hobo;
MCE::Hobo->create( sub { print "Hello from hobo\n" } )->join();
sub parallel {
my ($arg1) = @_;
print "Hello again, $arg1\n";
}
MCE::Hobo->create( \¶llel, $_ ) for 1 .. 3;
my @hobos = MCE::Hobo->list();
my @running = MCE::Hobo->list_running();
my @joinable = MCE::Hobo->list_joinable();
my @count = MCE::Hobo->pending();
# Joining is orderly, e.g. hobo1 is joined first, hobo2, hobo3.
$_->join() for @hobos;
# Joining occurs immediately as hobo(s) complete execution.
1 while MCE::Hobo->waitone();
my $hobo = mce_async { foreach (@files) { ... } };
$hobo->join();
if ( my $err = $hobo->error() ) {
warn("Hobo error: $err\n");
}
# Get a hobo's object
$hobo = MCE::Hobo->self();
# Get a hobo's ID
$tid = MCE::Hobo->tid(); # "$$.tid"
$tid = $hobo->tid();
$pid = MCE::Hobo->pid(); # $$
$pid = $hobo->pid();
# Test hobo objects
if ( $hobo1 == $hobo2 ) {
...
}
# Give other hobos a chance to run
MCE::Hobo->yield();
MCE::Hobo->yield(0.05);
# Return context, wantarray aware
my ($value1, $value2) = $hobo->join();
my $value = $hobo->join();
# Check hobo's state
if ( $hobo->is_running() ) {
sleep 1;
}
if ( $hobo->is_joinable() ) {
$hobo->join();
}
# Send a signal to a hobo
$hobo->kill('SIGUSR1');
# Exit a hobo
MCE::Hobo->exit();
DESCRIPTION
A Hobo is a migratory worker inside the machine that carries the asynchronous gene. Hobos are equipped with threads
-like capability for running code asynchronously. Unlike threads, each hobo is a unique process to the underlying OS. The IPC is managed by MCE::Shared
, which runs on all the major platforms including Cygwin.
MCE::Hobo
may be used as a standalone or together with MCE
including running alongside threads
.
The following is a parallel demonstration.
use strict;
use warnings;
use MCE::Hobo;
use MCE::Shared Sereal => 1; # Serialization via Sereal if available.
use MCE::Shared::Ordhash; # Ordered hash for non-shared use below.
# synopsis: head -20 file.txt | perl script.pl
my $ifh = MCE::Shared->handle( "<", \*STDIN ); # shared
my $ofh = MCE::Shared->handle( ">", \*STDOUT );
my $ary = MCE::Shared->array();
sub parallel_task {
my ( $id ) = @_;
while ( <$ifh> ) {
printf {$ofh} "[ %4d ] %s", $., $_;
# $ary->[ $. - 1 ] = "[ ID $id ] read line $.\n" ); # dereferencing
$ary->set( $. - 1, "[ ID $id ] read line $.\n" ); # faster via OO
}
}
my $hobo1 = MCE::Hobo->new( "parallel_task", 1 );
my $hobo2 = MCE::Hobo->new( \¶llel_task, 2 );
my $hobo3 = MCE::Hobo->new( sub { parallel_task(3) } );
$_->join for MCE::Hobo->list();
# search array -- single IPC
my @vals = $ary->vals( "val =~ / ID 2 /" );
print {*STDERR} join( "", @vals );
OVERRIDING DEFAULTS
The following list options which may be overridden when loading the module.
use Sereal qw( encode_sereal decode_sereal );
use CBOR::XS qw( encode_cbor decode_cbor );
use JSON::XS qw( encode_json decode_json );
use MCE::Hobo
freeze => \&encode_sereal, ## \&Storable::freeze
thaw => \&decode_sereal ## \&Storable::thaw
;
There is a simpler way to enable Sereal. The following will attempt to use Sereal if available, otherwise defaults to Storable for serialization.
use MCE::Hobo Sereal => 1;
use MCE::Shared Sereal => 1; # <-- supports Sereal only at this time
API DOCUMENTATION
- $hobo = MCE::Hobo->create( { posix_exit => 1 }, FUNCTION, ARGS )
- $hobo = MCE::Hobo->create( FUNCTION, ARGS )
- $hobo = MCE::Hobo->new( FUNCTION, ARGS )
-
This will create a new hobo that will begin execution with function as the entry point, and optionally ARGS for list of parameters. It will return the corresponding MCE::Hobo object, or undef if hobo creation failed.
Options may be specified via a hash structure. At this time,
posix_exit
is the only option supported which callsPOSIX::_exit(0)
when finished. The default isCORE::exit(0)
. Setposix_exit
to avoid all END and destructor processing.FUNCTION may either be the name of a function, an anonymous subroutine, or a code ref.
my $hobo = MCE::Hobo->create( "func_name", ... ); # or my $hobo = MCE::Hobo->create( sub { ... }, ... ); # or my $hobo = MCE::Hobo->create( \&func, ... );
The
new()
method is an alias forcreate()
. - mce_async { BLOCK } ARGS;
- mce_async { BLOCK };
-
mce_async
runs the block asynchronously similarly toMCE::Hobo-
create()>. It returns the hobo object, or undef if hobo creation failed.my $hobo = mce_async { foreach (@files) { ... } }; $hobo->join(); if ( my $err = $hobo->error() ) { warn("Hobo error: $err\n"); }
- $hobo->join()
-
This will wait for the corresponding hobo to complete its execution. In non-voided context,
join()
will return the value(s) of the entry point function.The context (void, scalar or list) for the return value(s) for
join
is determined at the time of joining and mostlywantarray
aware.my $hobo1 = MCE::Hobo->create( sub { my @res = qw(foo bar baz); return (@res); }); my @res1 = $hobo1->join(); # ( foo, bar, baz ) my $res1 = $hobo1->join(); # baz my $hobo2 = MCE::Hobo->create( sub { return 'foo'; }); my @res2 = $hobo2->join(); # ( foo ) my $res2 = $hobo2->join(); # foo
- $hobo1->equal( $hobo2 )
-
Tests if two hobo objects are the same hobo or not. Hobo comparison is based on process IDs. This is overloaded to the more natural forms.
if ( $hobo1 == $hobo2 ) { print("Hobos are the same\n"); } # or if ( $hobo1 != $hobo2 ) { print("Hobos differ\n"); }
- $hobo->error()
-
Hobos are executed in an
eval
context. This method will returnundef
if the hobo terminates normally. Otherwise, it returns the value of$@
associated with the hobo's execution status in itseval
context. - $hobo->exit()
-
This sends
'SIGQUIT'
to the hobo object, notifying hobo to exit. It returns the hobo object to allow for method chaining. It is important to join later if not immediately to not leave a zombie or defunct process.$hobo->exit()->join(); ... $hobo->join(); # later
- MCE::Hobo->exit()
-
A hobo can be exited at any time by calling
MCE::Hobo-
exit()>. This behaves the same asexit(status)
when called from the main process. - MCE::Hobo->finish()
-
This class method is called automatically by
END
, but may be called explicitly. Two shared objects toMCE::Shared
are destroyed. An error is emitted via croak if there are active hobos not yet joined.MCE::Hobo->create( 'task1', $_ ) for 1 .. 4; $_->join for MCE::Hobo->list(); MCE::Hobo->create( 'task2', $_ ) for 1 .. 4; $_->join for MCE::Hobo->list(); MCE::Hobo->create( 'task3', $_ ) for 1 .. 4; $_->join for MCE::Hobo->list(); MCE::Hobo->finish();
- $hobo->is_running()
-
Returns true if a hobo is still running.
- $hobo->is_joinable()
-
Returns true if the hobo has finished running and not yet joined.
- $hobo->kill( 'SIG...' )
-
Sends the specified signal to the hobo. Returns the hobo object to allow for method chaining. As with
exit
, it is important to join eventually if not immediately to not leave a zombie or defunct process.$hobo->kill('SIG...')->join();
The following is a parallel demonstration comparing
MCE::Shared
againstRedis
andRedis::Fast
on a Fedora 23 VM. Joining begins after all workers have been notified to quit.use Time::HiRes qw(time); use Redis; use Redis::Fast; use MCE::Hobo; use MCE::Shared; my $redis = Redis->new(); my $rfast = Redis::Fast->new(); my $array = MCE::Shared->array(); sub parallel_redis { my ($_redis) = @_; my ($count, $quit, $len) = (0, 0); # instead, use a flag to exit loop $SIG{'QUIT'} = sub { $quit = 1 }; while (1) { $len = $_redis->rpush('list', $count++); last if $quit; } $count; } sub parallel_array { my ($count, $quit, $len) = (0, 0); # do not exit from inside handler $SIG{'QUIT'} = sub { $quit = 1 }; while (1) { $len = $array->push($count++); last if $quit; } $count; } sub benchmark_this { my ($desc, $num_hobos, $timeout, $code, @args) = @_; my ($start, $total) = (time(), 0); MCE::Hobo->new($code, @args) for 1..$num_hobos; sleep $timeout; # joining is not immediate; ok $_->kill('QUIT') for MCE::Hobo->list(); # joining later; ok $total += $_->join() for MCE::Hobo->list(); printf "$desc <> duration: %0.03f secs, count: $total\n", time() - $start; sleep 0.2; } benchmark_this('Redis ', 8, 5.0, \¶llel_redis, $redis); benchmark_this('Redis::Fast', 8, 5.0, \¶llel_redis, $rfast); benchmark_this('MCE::Shared', 8, 5.0, \¶llel_array);
- MCE::Hobo->list()
-
Returns a list of all hobos not yet joined.
@hobos = MCE::Hobo->list();
- MCE::Hobo->list_running()
-
Returns a list of all hobos that are still running.
@hobos = MCE::Hobo->list_running();
- MCE::Hobo->list_joinable()
-
Returns a list of all hobos that have completed running. Thus, ready to be joined without blocking.
@hobos = MCE::Hobo->list_joinable();
- MCE::Hobo->pending()
-
Returns a count of all hobos not yet joined.
$count = MCE::Hobo->pending();
- $hobo->result()
-
Returns the result obtained by
join
,waitone
, orwaitall
. If the process has not yet exited, waits for the corresponding hobo to complete its execution.use MCE::Hobo; use Time::HiRes qw(sleep); sub task { my ($id) = @_; sleep $id * 0.333; return $id; } MCE::Hobo->create('task', $_) for ( reverse 1 .. 3 ); # 1 while MCE::Hobo->waitone; while ( my $hobo = MCE::Hobo->waitone() ) { my $err = $hobo->error() // 'no error'; my $res = $hobo->result(); my $pid = $hobo->pid(); print "[$pid] $err : $res\n"; }
Like
join
described above, the context (void, scalar or list) for the return value(s) is determined at the timeresult
is called and mostlywantarray
aware.my $hobo1 = MCE::Hobo->create( sub { my @res = qw(foo bar baz); return (@res); }); my @res1 = $hobo1->result(); # ( foo, bar, baz ) my $res1 = $hobo1->result(); # baz my $hobo2 = MCE::Hobo->create( sub { return 'foo'; }); my @res2 = $hobo2->result(); # ( foo ) my $res2 = $hobo2->result(); # foo
- MCE::Hobo->self()
-
Class method that allows a hobo to obtain it's own MCE::Hobo object.
- $hobo->pid()
- $hobo->tid()
-
Returns the ID of the hobo. TID is composed of process and thread IDs together as a string value.
PID: $$ TID: "$$.tid"
- MCE::Hobo->pid()
- MCE::Hobo->tid()
-
Class methods that allows a hobo to obtain its own ID.
- MCE::Hobo->waitone()
- MCE::Hobo->waitall()
-
Meaningful for the manager process only, waits for one or all hobos to complete execution. Afterwards, returns the corresponding hobo(s). If a hobo does not exist, returns the
undef
value or an empty list forwaitone
andwaitall
respectively.use MCE::Hobo; use Time::HiRes qw(sleep); sub task { my $id = shift; sleep $id * 0.333; return $id; } MCE::Hobo->create('task', $_) for ( reverse 1 .. 3 ); # join, traditional use case $_->join() for MCE::Hobo->list(); # waitone, simplistic use case 1 while MCE::Hobo->waitone(); # waitone while ( my $hobo = MCE::Hobo->waitone() ) { my $err = $hobo->error() // 'no error'; my $res = $hobo->result(); my $pid = $hobo->pid(); print "[$pid] $err : $res\n"; } # waitall my @hobos = MCE::Hobo->waitall(); for ( @hobos ) { my $err = $_->error() // 'no error'; my $res = $_->result(); my $pid = $_->pid(); print "[$pid] $err : $res\n"; }
- MCE::Hobo->yield( floating_seconds )
-
Let this hobo yield CPU time to other hobos. By default, the class method calls
sleep(0.0002)
on Unix andsleep(0.015)
on Windows including Cygwin.MCE::Hobo->yield(); MCE::Hobo->yield(0.05);
CREDITS
The inspiration for MCE::Hobo
comes from wanting threads
-like behavior for processes. Both can run side-by-side including safe-use by MCE workers. Likewise, the documentation resembles threads
.
The inspiration for waitall
and waitone
comes from Parallel::WorkUnit
.
SEE ALSO
INDEX
AUTHOR
Mario E. Roy, <marioeroy AT gmail DOT com>