Perl IPC using dynamic handles in hash

gansvv has asked for the wisdom of the Perl Monks concerning the following question:

Hi,

I am trying to get 14 child processes to talk with the parent and send back data. I have 14 pipes with dynamic handles - using a hash, with hostname as the key (because I need to be able to uniquely identify which child process sent the data too). However, I am unable to read the data back in the parent. All I get are GLOB values. Code snippets are below. Any help is greatly appreciated!

foreach $host (@hosts) {
   pipe($fhr{$host}, $fhw{$host});
   if (fork() == 0) { # child process spawned
      #do stuff and then write to pipe like this:
      close $fhr{$host};
      print { $fhw{$host} } "$mystr";
      close $fhw{$host};
   }
}

while (wait() != -1) { #wait for children to finish }


foreach $host (@hosts) {
    close $fhw{$host};
    chomp ($mystring=<$fhr{$host}>);
    close $fhr{$host};
    print "DATA from $host: $mystring";
}
[download]

I think the problem is with the chomp line. Am I reading from the pipe correctly?

Comment on Perl IPC using dynamic handles in hash Download Code

Replies are listed 'Best First'.
Re: Perl IPC using dynamic handles in hash by BrowserUk (Patriarch) on Jun 08, 2011 at 00:44 UTC
Switch that to: `chomp( $mystring = readline( $fhr{ $host } ) );` [download] In theory, you can also use curlies to disambiguate: `chomp( $mystring = < {$fhr{$host}} > );` [download] but I've encountered situations when that didn't seem to work. readline seems preferable anyway. Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l] [select]
Re^2: Perl IPC using dynamic handles in hash by gansvv (Initiate) on Jun 08, 2011 at 17:41 UTC
Yes, I had tried the curlies and they did not work. Readline works like a charm. Thanks a ton!	[reply]