I have a parent that spawns a bunch of children, up to 10 at any one time, to do some 'mostly-idle' processing. My question is, how to i get the results back from each child? Previously i've used the exit status of the child, which is fine for simple return values, but now i have a complex-data-structure to be returned (although can easily be encoded into a string by Data::Dumper if necessary). I've experimented with pipes but they only seem to work with 1 parent - 1 child relationship. IPC::Shareable looks to do what i want, but i wanted to get input from others to see if there was a simpler solution.

My code so far, if anyone's interested: 

my( %pid );

foreach my $num ( "01" .. "25" )
{
  # if max processes, wait for one to finish
  if( keys( %pid ) >= 10 ) { &reap() }
  
  if( my $pid = fork() )  # parent
  {
    $pid{$pid} = $num;
  }
  else                    # child
  {
    &child( $num );
    exit 0;
  }
}

# reap remaining processes
while( %pid ) { &reap() }

# <collect data>

sub reap
{
  my( $pid ) = wait();
  
  if( $pid == -1  ) { die( "no more kids to reap!\n" ) }
  if(! $pid{$pid} ) { die( "why did I see $pid?\n"   ) }
  
  delete( $pid{$pid} );
}

sub child
{
  my( $num ) = $_[0];
  print "child $num spawned\n";
  # <send data>
}

[download]

Thanks all!

- ><iper 

my JAPH:
  print"Just another Perl hacker\n";
  #    ^ look, no space! pretty tricky huh?

[download]

In reply to Receiving data from many children by xiper

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