MCE::Hobo - A threads-like parallelization module
This document describes MCE::Hobo version 1.816
use MCE::Hobo; MCE::Hobo->create( sub { print "Hello from hobo\n" } )->join(); sub parallel { my ($arg1) = @_; print "Hello again, $arg1\n" if defined($arg1); print "Hello again, $_\n"; # same thing } 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 $pid = MCE::Hobo->pid(); # $$ $pid = $hobo->pid(); $tid = MCE::Hobo->tid(); # $$ same thing $tid = $hobo->tid(); # 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();
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.
threads
MCE::Shared
MCE::Hobo may be used as a standalone or together with MCE including running alongside threads. An exception is made on the Windows platform in MCE::Shared 1.807 and later to spawn workers via threads instead of child processes for better reliability.
MCE::Hobo
MCE
The following is a parallel demonstration.
use strict; use warnings; use MCE::Hobo; use MCE::Shared; 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 );
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.
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, ... );
Options may be specified via a hash structure. At this time, posix_exit and hobo_timeout are the only options supported. Set posix_exit to avoid all END and destructor processing. Set hobo_timeout, in number of seconds, if you want the hobo process to terminate after some time. The default is 0 for no timeout.
posix_exit
hobo_timeout
0
Many modules on CPAN are not thread-safe nor safe to use with many processes. The posix_exit option must be set explicitly if your application is crashing, due to a module with a DESTROY or END block not accounting for the process ID $$.$tid the object was constructed under: e.g. Cache::BDB.
DESTROY
END
$$.$tid
Cache::BDB
Constructing a Hobo inside a thread implies posix_exit = 1> or if present CGI.pm, FCGI.pm, Gearman::Util, Gearman::XS, Mojo::IOLoop, or Tk.
posix_exit =
my $hobo1 = MCE::Hobo->create( { posix_exit => 1 }, sub { ... } ); $hobo1->join; my $hobo2 = MCE::Hobo->create( { hobo_timeout => 3 }, sub { sleep 1 for ( 1 .. 9 ); } ); $hobo2->join; if ( $hobo2->error() eq "Hobo timed out\n" ) { ... }
The new() method is an alias for create().
new()
create()
mce_async runs the block asynchronously similarly to MCE::Hobo-create()>. It returns the hobo object, or undef if hobo creation failed.
mce_async
MCE::Hobo-
my $hobo = mce_async { foreach (@files) { ... } }; $hobo->join(); if ( my $err = $hobo->error() ) { warn("Hobo error: $err\n"); }
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.
join()
The context (void, scalar or list) for the return value(s) for join is determined at the time of joining and mostly wantarray aware.
join
wantarray
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
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"); }
Hobos are executed in an eval context. This method will return undef if the hobo terminates normally. Otherwise, it returns the value of $@ associated with the hobo's execution status in its eval context.
eval
undef
$@
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.
'SIGQUIT'
$hobo->exit()->join(); ... $hobo->join(); # later
A hobo can be exited at any time by calling MCE::Hobo-exit()>. This behaves the same as exit(status) when called from the main process.
exit(status)
This class method is called automatically by END, but may be called explicitly. Two shared objects to MCE::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();
Returns true if a hobo is still running.
Returns true if the hobo has finished running and not yet joined.
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.
exit
$hobo->kill('SIG...')->join();
The following is a parallel demonstration comparing MCE::Shared against Redis and Redis::Fast on a Fedora 23 VM. Joining begins after all workers have been notified to quit.
Redis
Redis::Fast
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);
Returns a list of all hobos not yet joined.
@hobos = MCE::Hobo->list();
Returns a list of all hobos that are still running.
@hobos = MCE::Hobo->list_running();
Returns a list of all hobos that have completed running. Thus, ready to be joined without blocking.
@hobos = MCE::Hobo->list_joinable();
Returns a count of all hobos not yet joined.
$count = MCE::Hobo->pending();
Returns the result obtained by join, waitone, or waitall. If the process has not yet exited, waits for the corresponding hobo to complete its execution.
waitone
waitall
use MCE::Hobo; use Time::HiRes qw(sleep); sub task { my ($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 time result is called and mostly wantarray aware.
result
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
Class method that allows a hobo to obtain it's own MCE::Hobo object.
Returns the ID of the hobo.
pid: $$.$tid # Windows (only), with thread id tid: $$.$tid # same thing pid: $$ # Cygwin and UNIX platforms tid: $$
Class methods that allows a hobo to obtain its own ID.
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 for waitone and waitall 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"; }
Let this hobo yield CPU time to other hobos. By default, the class method calls sleep(0.0005) on UNIX and sleep(0.015) on Windows including Cygwin.
sleep(0.0005)
sleep(0.015)
MCE::Hobo->yield(); MCE::Hobo->yield(0.05);
Making an executable is possible with the PAR::Packer module. On the Windows platform, threads, threads::shared, and exiting via threads are all necessary for the binary to exit successfully.
# https://metacpan.org/pod/PAR::Packer # https://metacpan.org/pod/pp # # pp -o demo.exe demo.pl # ./demo.exe use strict; use warnings; use if $^O eq "MSWin32", "threads"; use if $^O eq "MSWin32", "threads::shared"; use Time::HiRes (); # include minimum dependencies for MCE::Hobo use Storable (); use IO::FDPass (); # optional: for MCE::Shared->condvar, handle, queue use Sereal (); # optional: faster serialization, may omit Storable use MCE::Hobo; # 1.808 or later on Windows use MCE::Shared; my $seq_a = MCE::Shared->sequence( 1, 30 ); sub task { my ( $id ) = @_; while ( defined ( my $num = $seq_a->next ) ) { print "$id: $num\n"; } } MCE::Hobo->new( \&task, $_ ) for 1 .. 2; MCE::Hobo->waitall; threads->exit(0) if $INC{"threads.pm"};
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.
Parallel::WorkUnit
forks
forks::BerkeleyDB
Parallel::ForkManager
Parallel::Loops
Parallel::Prefork
Proc::Fork
Thread::Tie
MCE, MCE::Shared
Mario E. Roy, <marioeroy AT gmail DOT com>
To install MCE::Shared, copy and paste the appropriate command in to your terminal.
cpanm
cpanm MCE::Shared
CPAN shell
perl -MCPAN -e shell install MCE::Shared
For more information on module installation, please visit the detailed CPAN module installation guide.