quick and dirty test script to work out how reads on non-blocking pipes behave

pipetest.pl

#! /usr/bin/perl

use strict;
use warnings;

use feature qw(say);

use IO::Select;
use IO::Pipe;

my $select = new IO::Select;

for my $c (1 .. 20) {
  my $pipe = IO::Pipe->new();

  if (my $childpid = fork()) {
    say "Spawned child with pid $childpid";
    $pipe->reader;
    $pipe->blocking(0);
    $select->add($pipe);
  } else {
    $pipe->writer;
    $pipe->autoflush;
    select $pipe;

    my $timeout = int(rand(10));
    say "[$$] Inside child";
    say "[$$]  sleeping for $timeout seconds until next line";

    my $sleeptime = sleep($timeout);
    say "[$$] Slept for $sleeptime seconds, now I'm done";

    exit(0);
  }
}

say "Finished spawning children";

while (my @ready_fh = $select->can_read) {
  for my $hd (@ready_fh) {
    if ($hd->eof) {
      $select->remove($hd);
    }

    while (defined(my $_= $hd->getline)) {
      print "Got line: $_";
    }
  }
}