Re: Does IO::Select work? Anywhere?

[ikegami]

in reply to Does IO::Select work? Anywhere?

One-way comm:

use strict;
use warnings;

use IO::Select qw( );
use IPC::Open3 qw( open3 );
use Symbol     qw( gensym );

sub launch {
   my ($id) = @_;
   open(local *TO_CHILD, '<', '/dev/null') or die $!;
   *TO_CHILD if 0;
   my $pid = open3(
      '<&TO_CHILD',
      my $from_child = gensym(),
      '>&STDERR',
      perl => ( -e => 'use Time::HiRes qw( sleep ); $|=1; for (1..rand
+(10)+5) { sleep(0.100 + rand(100)/1000); print "a" }' ),
   );
   return { id => $id, pid => $pid, pipe => $from_child, buf => '' };
}

my %children = map { $_->{pipe} => $_ } map launch($_), 1..2;

my $sel = IO::Select->new( map $_->{pipe}, values %children );
while ($sel->count) {
   for my $fh ($sel->can_read(0.050)) {
      my $child = $children{$fh};
      our $buf; local *buf = \( $child->{buf} );

      my $rv = sysread($fh, $buf, 64*1024, length($buf));
      die $! if !defined($rv);

      if (!$rv) {
         delete $children{$fh};
         $sel->remove($fh);
         waitpid($child->{pid}, 0);
         printf("%s: Exited with %08X after receiving %s\n", $child->{
+id}, $?, $buf);
         next;
      }

      printf("%s: Received some data\n", $child->{id});
   }
}

1: Received some data
2: Received some data
1: Received some data
2: Received some data
1: Received some data
2: Received some data
1: Received some data
2: Received some data
1: Received some data
1: Exited with 00000000 after receiving aaaaa
2: Received some data
2: Received some data
2: Received some data
2: Exited with 00000000 after receiving aaaaaaa

[Athanasius]

Doesn’t work for me.  :-(

I copied-and-pasted the code into a file named “344_SoPW.pl” and ran it with the following results:

19:46 >perl -c 344_SoPW.pl
344_SoPW.pl syntax OK

19:46 >perl 344_SoPW.pl
syntax error at -e line 1, at EOF
Execution of -e aborted due to compilation errors.
syntax error at -e line 1, at EOF
Execution of -e aborted due to compilation errors.
Terminating on signal SIGINT(2)

19:47 >

(Had to Control-C as it just hung.) My configuration:

• Windows Vista 32-bit
• Strawberry perl 5, version 16, subversion 0 (v5.16.0) built for MSWin32-x86-multi-thread-64int
• IO::Select v1.21
• IPC::Open3 v1.12
• Symbol v1.07

Hope this info is useful,

[BrowserUk]

Doesn’t work for me. ... Windows ...

It won't. Pipe handles aren't selectable under windows -- which makes it a pretty useless demo for anyone who uses windows.

[Anonymous Monk]

:) Really, you don't have /dev/null on windows? Use File::Spec->devnull

naturally fixing those portability issues , select loop is forever

use File::Spec();

sub launch {
   my ($id) = @_;
   open(local *TO_CHILD, '<', File::Spec->devnull ) or die $!;
   *TO_CHILD if 0;
   my $pid = open3(
      '<&TO_CHILD',
      my $from_child = gensym(),
      '>&STDERR',
#~       perl => ( -e => 'use Time::HiRes qw( sleep ); $|=1; for (1..r
+and(10)+5) { sleep(0.100 + rand(100)/1000); print "a" }' ),

      $^X => ( -e => 'use Time::HiRes qw( sleep ); $|=1; for (1..rand(
+10)+5) { sleep(0.100 + rand(100)/1000); print q{a} }' ),
   );
   return { id => $id, pid => $pid, pipe => $from_child, buf => '' };
}

Perl version: v5.14.1 on MSWin32
Carp               - 1.26
Devel::VersionDump - 0.02
Exporter           - 5.66
File::Spec         - 3.33
File::Spec::Unix   - 3.33
File::Spec::Win32  - 3.33
IO::Select         - 1.20
IPC::Open3         - 1.09
Symbol             - 1.07
constant           - 1.21
strict             - 1.04
vars               - 1.02
warnings           - 1.12
warnings::register - 1.02