earlati2 has asked for the wisdom of the Perl Monks concerning the following question:

I write an hadler for mod_perl.

The handler seems ok and it works well but if I create a thread inside this handler with fork the new thread will never destroy.

I include the following code as example :

$pid = fork();
if( $pid == 0 )
{
    my $p_pid;
$p_pid = getppid;
print "+START Child process: $$.$p_pid " ;
sleep 1;
print "+EXIT Child process: $$.$p_pid ";
exit;
}
else
{
     my $status_pid = 0;
}

[download]

each time I create the thread I got a new instance of http, which will not disappear , even after exit

nobody 20873 20816 0 09:16 ? 00:00:00 /usr/local/apache/bin/httpd
nobody 20874 20817 0 09:16 ? 00:00:00 /usr/local/apache/bin/httpd

[download]

Any suggestion ?

regards, Enzo

Edited by planetscape - added code tags; changed pre to code tags

( keep:2 edit:28 reap:0 )

Replies are listed 'Best First'.
Re: thread inside mod_perl handler will never been released
by jeteve (Pilgrim) on Jul 27, 2006 at 09:06 UTC

    Your father should wait for your child, otherwise the child might become a zombie... Brrrrr.

    see : fork

    If you really want the father to resign his soon, hence letting the son dying alone, consider the following code: 

    #! /usr/bin/perl
#
# Playing with processes ...

use POSIX qw(setsid);

if ( $pid = fork()){
  print "I am the father..\n";
  print " Child pid : $pid \n";
 
}
else{
  setsid();
  close STDIN  ; #  Inside a web server
  close STDERR ; #  Idem
  close STDOUT ; #  Idem
  print "\nI am the child \n";
  print "I am $$\n";
  $timer= 30 ;
  sleep($timer);
  print "\nWahhh, i am awake after $timer seconds \n";
}

exit 0 ;

    [download]
    Hope it helps.

    -- Nice photos of naked perl sources here !

[reply]
[d/l]

      Using setsid and exit I got extra httpd daemon at each fork.

      So it doesn' seem a good solution

      If I use Core::exit(0) instead of exit I got an httpd daemon in zombie state.

          $pid = fork();
    if( $pid == 0 )
    {
        setsid();
        # -----------------------------------------
        close STDIN;
        close STDOUT;
        close STDERR;
        # -----------------------------------------
        my $p_pid;
          $p_pid = getppid;
        ae_util::mylog( "START Child process: $$.$p_pid " );
        sleep 1;
        ae_util::mylog( "EXIT Child process: $$.$p_pid " );
        # CORE::exit(0);
         exit;
    }

      [download]

      I found another solution which is more simple and seems to works well:

      $SIG{CHLD} = 'IGNORE';

      and 

          $pid = fork();
    if( $pid == 0 )
    {
        # -----------------------------------------
        close STDIN;
        close STDOUT;
        close STDERR;
        # -----------------------------------------
        my $p_pid;
        $p_pid = getppid;
        ae_util::mylog( "START Child process: $$.$p_pid " );
        sleep 1;
        ae_util::mylog( "EXIT Child process: $$.$p_pid " );
         CORE::exit(0);
    }

      [download]

      Do you known if that solution ( ignore SIGCHLD signal ) have some drawback ?

      Edited by planetscape - changed pre to code tags; added rudimentary formatting

      Read more... view votes (25 Bytes)

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