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.\" ========================================================================
.\"
.IX Title "Mojo::IOLoop::Subprocess 3pm"
.TH Mojo::IOLoop::Subprocess 3pm "2019-02-05" "perl v5.28.1" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH "NAME"
Mojo::IOLoop::Subprocess \- Subprocesses
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\&  use Mojo::IOLoop::Subprocess;
\&
\&  # Operation that would block the event loop for 5 seconds
\&  my $subprocess = Mojo::IOLoop::Subprocess\->new;
\&  $subprocess\->run(
\&    sub {
\&      my $subprocess = shift;
\&      sleep 5;
\&      return \*(Aq♥\*(Aq, \*(AqMojolicious\*(Aq;
\&    },
\&    sub {
\&      my ($subprocess, $err, @results) = @_;
\&      say "Subprocess error: $err" and return if $err;
\&      say "I $results[0] $results[1]!";
\&    }
\&  );
\&
\&  # Start event loop if necessary
\&  $subprocess\->ioloop\->start unless $subprocess\->ioloop\->is_running;
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
Mojo::IOLoop::Subprocess allows Mojo::IOLoop to perform computationally
expensive operations in subprocesses, without blocking the event loop.
.SH "EVENTS"
.IX Header "EVENTS"
Mojo::IOLoop::Subprocess inherits all events from Mojo::EventEmitter and
can emit the following new ones.
.SS "progress"
.IX Subsection "progress"
.Vb 4
\&  $subprocess\->on(progress => sub {
\&    my ($subprocess, @data) = @_;
\&    ...
\&  });
.Ve
.PP
Emitted in the parent process when the subprocess calls the
progress method.
.SS "spawn"
.IX Subsection "spawn"
.Vb 4
\&  $subprocess\->on(spawn => sub {
\&    my $subprocess = shift;
\&    ...
\&  });
.Ve
.PP
Emitted in the parent process when the subprocess has been spawned.
.PP
.Vb 5
\&  $subprocess\->on(spawn => sub {
\&    my $subprocess = shift;
\&    my $pid = $subprocess\->pid;
\&    say "Performing work in process $pid";
\&  });
.Ve
.SH "ATTRIBUTES"
.IX Header "ATTRIBUTES"
Mojo::IOLoop::Subprocess implements the following attributes.
.SS "deserialize"
.IX Subsection "deserialize"
.Vb 2
\&  my $cb      = $subprocess\->deserialize;
\&  $subprocess = $subprocess\->deserialize(sub {...});
.Ve
.PP
A callback used to deserialize subprocess return values, defaults to using
Storable.
.PP
.Vb 4
\&  $subprocess\->deserialize(sub {
\&    my $bytes = shift;
\&    return [];
\&  });
.Ve
.SS "ioloop"
.IX Subsection "ioloop"
.Vb 2
\&  my $loop    = $subprocess\->ioloop;
\&  $subprocess = $subprocess\->ioloop(Mojo::IOLoop\->new);
.Ve
.PP
Event loop object to control, defaults to the global Mojo::IOLoop singleton.
Note that this attribute is weakened.
.SS "serialize"
.IX Subsection "serialize"
.Vb 2
\&  my $cb      = $subprocess\->serialize;
\&  $subprocess = $subprocess\->serialize(sub {...});
.Ve
.PP
A callback used to serialize subprocess return values, defaults to using
Storable.
.PP
.Vb 4
\&  $subprocess\->serialize(sub {
\&    my $array = shift;
\&    return \*(Aq\*(Aq;
\&  });
.Ve
.SH "METHODS"
.IX Header "METHODS"
Mojo::IOLoop::Subprocess inherits all methods from Mojo::EventEmitter and
implements the following new ones.
.SS "pid"
.IX Subsection "pid"
.Vb 1
\&  my $pid = $subprocess\->pid;
.Ve
.PP
Process id of the spawned subprocess if available.
.SS "progress"
.IX Subsection "progress"
.Vb 1
\&  $subprocess\->progress(@data);
.Ve
.PP
Send data serialized with Storable to the parent process at any time during
the subprocess's execution. Must be called by the subprocess and emits the
\&\*(L"progress\*(R" event in the parent process with the data.
.PP
.Vb 10
\&  # Send progress information to the parent process
\&  $subprocess\->run(
\&    sub {
\&      my $subprocess = shift;
\&      $subprocess\->progress(\*(Aq0%\*(Aq);
\&      sleep 5;
\&      $subprocess\->progress(\*(Aq50%\*(Aq);
\&      sleep 5;
\&      return \*(AqHello Mojo!\*(Aq;
\&    },
\&    sub {
\&      my ($subprocess, $err, @results) = @_;
\&      say \*(AqProgress is 100%\*(Aq;
\&      say $results[0];
\&    }
\&  );
\&  $subprocess\->on(progress => sub {
\&    my ($subprocess, @data) = @_;
\&    say "Progress is $data[0]";
\&  });
.Ve
.SS "run"
.IX Subsection "run"
.Vb 1
\&  $subprocess = $subprocess\->run(sub {...}, sub {...});
.Ve
.PP
Execute the first callback in a child process and wait for it to return one or
more values, without blocking \*(L"ioloop\*(R" in the parent process. Then execute
the second callback in the parent process with the results. The return values of
the first callback and exceptions thrown by it, will be serialized with
Storable, so they can be shared between processes.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Mojolicious, Mojolicious::Guides, <https://mojolicious.org>.