in reply to Parent process dies unexpected

I don't know why, but commenting out the exit fixes it for FreeBSD (v5.8.0 built for i386-freebsd). Why would calling exit in the child exit the parent?

Update: The parent doesn't exit. $SIG{'CHLD'} is being called, but accept is returning false due to "Interrupted system call" ($! == 4). Maybe the CHLD signal interrupts accept?? no, that can't be it, cause it works fine without the call to exit. In any case, the following fix seems to work:

use POSIX;

...

REDO_ACCEPT: {
  while ($client = $sock->accept())
  {
     ...
  }

  redo if $! == EINTR;
}

[download]

There might be a better way. I'm not familiar with this stuff. I just deduced this from debugging.

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Re^2: Parent process dies unexpected
by gnork (Scribe) on Sep 29, 2004 at 07:23 UTC
    Hi, ikegami!

    Thx for the hint. How did you debug the forked child? Or were you using strace/truss?
    Anyway, I'm going to try your suggestion and report back.
    Another question: Would you consider this a bug?

    Best regards,
    gnork

    cat /dev/world | perl -e "(/(^.*? \?) 42\!/) && (print $1))"
    errors->(c)
[reply]

      First, I commented out the exit. It "fixed" the problem, but I deemed the solution unacceptable. Behold my fancy debugger!

      #!/usr/bin/perl

use strict;
use IO::Socket;
use constant MYPORT => 2000;

$|=1;  <-------

my $sock = '';
my $client = '';

$sock = IO::Socket::INET->new(LocalPort => MYPORT,
                              Type      => SOCK_STREAM,
                              Proto     => 'tcp',
                              Reuse     => 1,
                              Listen    => 10)
or die "trouble creating socket: $@\n";

$SIG{'CHLD'} = sub { 
print('!');  <-------
wait();
print('@');  <-------
$client->close();
print('#');  <-------
};
print "Accepting connections on Port ", MYPORT, "...\n";
while ($client = $sock->accept())
  {
  print "Accepted connection from ",
        $client->peerhost(), ":", $client->peerport(), "\n";

  if (fork() == 0)
    {
    while (<$client>)
      {
      chomp;
      print $client scalar(reverse($_)), "\n";
      }
    exit 1;
    }
  }

print('$');         <-------
print(0+$!, "$!");  <-------

      [download]

      When I noticed '!@#' was being printed, I added '$'. Then I checked why accept was returning by adding a print of $!.

      Since I'm not sure what the cause is, I'm not sure if I consider it a bug. In any case, the behavious should be documented.

[reply]
[d/l]
        Hi, ikegami!

        Thx for your effort, we are digging in a bit deeper now.
        Maybe the weekend brings some new results which i will promptly let you know.

        Have a nice weekend,
        Gnork

        cat /dev/world | perl -e "(/(^.*? \?) 42\!/) && (print $1))"
        errors->(c)
[reply]

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