Beefy Boxes and Bandwidth Generously Provided by pair Networks
Welcome to the Monastery
 
PerlMonks  

comment on

( [id://3333]=superdoc: print w/replies, xml ) Need Help??

MCE::Channel is included in recent MCE releases. MCE::Flow allows running multiple tasks simultaneously.

So here is a great demonstration for MCE::Flow and MCE::Channel. The benefit is that the manager process does little work and better able to accommodate workers requesting input with minimum latency. The bottleneck is now the gifout task which is a separate worker. Notice user_begin and user_end called for the first task only by checking MCE->task_id. Notice also max_workers taking an array ref for specifying how many workers for each task.

The following demonstration was made possible by PerlMonks. Thanks vr for providing GD tips. Thank you Anonymous Monk for posting.

use strict; use warnings; use feature 'say'; use Imager; use MCE::Flow; use MCE::Channel; use Time::HiRes 'time'; use GD; STDOUT->autoflush; my $start = time; my $chnl = MCE::Channel->new(); my $count = 0; my $bkg; MCE::Flow->init( max_workers => [ MCE::Util::get_ncpu() - 1, 1 ], chunk_size => 1, init_relay => '', gather => sub { print "\r", $count++; }, user_begin => sub { if (MCE->task_id == 0) { $bkg = Imager->new(xsize=>800, ysize=>600); $bkg->filter(type=>"gradgen", xo=>[ 100, 300, 600 ], yo=>[ 100, 300, 100 ], colors=>[ qw(red blue green) ]); $bkg->filter(type=>"noise", amount=>12, subtype=>0) } }, user_end => sub { if (MCE->task_id == 0) { $chnl->end; } } ); sub task_frames { my ($mce, $chunk_ref, $chunk_id) = @_; my @i_data; for my $x (@{ $chunk_ref }) { my $i = $bkg-> copy; $i->string( text => $x, color => Imager::Color->new('ffffff'), font => Imager::Font->new( # file => '/usr/share/fonts/truetype/msttcorefonts/cour.ttf', # + Ubuntu # file => '/System/Library/Fonts/Courier.dfont', face => 'Courier New', # mswin size => 420, aa => 1), x => 25, y => 500, ); $i->write(data => \my $data, type => 'gif'); push @i_data, $data; MCE->gather($x); } MCE::relay { $chnl->send(\@i_data) }; } sub task_gifout { my $image; my $gifdata; while ( my $i_data_ref = $chnl->recv ) { if (!defined $gifdata) { $image = GD::Image-> newFromGifData( shift @{ $i_data_ref } ) +; $gifdata = $image-> gifanimbegin( 0,0 ); $gifdata .= $image-> gifanimadd( 1,0,0,1,1 ); } while ( my $data = shift @{ $i_data_ref } ) { my $frame = GD::Image-> newFromGifData( $data ); $gifdata .= $frame-> gifanimadd( 1,0,0,1,1 ); } } $gifdata .= $image-> gifanimend; open my $fh, '>:raw', 'gd.gif'; print $fh $gifdata; close $fh; } mce_flow \&task_frames, \&task_gifout, [ 0 .. 319 ]; MCE::Flow->finish; print " frame GIF done!\n"; printf "compute time: %0.3fs\n", time - $start;

There is a lot of parallel going on :) Although workers complete sooner, the manager process still waits for all tasks to finish before MCE::Flow exits.

Regards, Mario


In reply to Re^7: MCE segmentation fault - MCE::Flow + MCE::Channel by marioroy
in thread MCE segmentation fault by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others perusing the Monastery: (6)
As of 2024-03-29 01:19 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found