Paul Evans > IO-Async-0.60 > IO::Async::Routine



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Module Version: 0.60   Source   Latest Release: IO-Async-0.63


IO::Async::Routine - execute code in an independent sub-process


 use IO::Async::Routine;
 use IO::Async::Channel;

 use IO::Async::Loop;
 my $loop = IO::Async::Loop->new;

 my $nums_ch = IO::Async::Channel->new;
 my $ret_ch  = IO::Async::Channel->new;

 my $routine = IO::Async::Routine->new(
    channels_in  => [ $nums_ch ],
    channels_out => [ $ret_ch ],

    code => sub {
       my @nums = @{ $nums_ch->recv };
       my $ret = 0; $ret += $_ for @nums;

       # Can only send references
       $ret_ch->send( \$ret );

    on_finish => sub {
       say "The routine aborted early - $_[-1]";

 $loop->add( $routine );

 $nums_ch->send( [ 10, 20, 30 ] );
    on_recv => sub {
       my ( $ch, $totalref ) = @_;
       say "The total of 10, 20, 30 is: $$totalref";



This subclass of IO::Async::Process contains a body of code and executes it in a sub-process, allowing it to act independently of the main program. Once set up, all communication with the code happens by values passed into or out of the Routine via IO::Async::Channel objects.

Because the code running inside the Routine runs within its own process, it is isolated from the rest of the program, in terms of memory, CPU time, and other resources, and perhaps most importantly in terms of control flow. The code contained within the Routine is free to make blocking calls without stalling the rest of the program. This makes it useful for using existing code which has no option not to block within an IO::Async-based program.

To create asynchronous wrappers of functions that return a value based only on their arguments, and do not generally maintain state within the process it may be more convenient to use an IO::Async::Function instead, which uses an IO::Async::Routine to contain the body of the function and manages the Channels itself.


The following named parameters may be passed to new or configure:

channels_in => ARRAY of IO::Async::Channel

ARRAY reference of IO::Async::Channel objects to set up for passing values in to the Routine.

channels_out => ARRAY of IO::Async::Channel

ARRAY reference of IO::Async::Channel objects to set up for passing values out of the Routine.

code => CODE

CODE reference to the body of the Routine, to execute once the channels are set up.


This class provides no additional methods, other than those provided by IO::Async::Process.


Paul Evans <>

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