http://www.perlmonks.org?node_id=714909


in reply to Problem w/ forking CGI script

In my experience, you also need to close STDERR in the child (at least with recent Apaches), not only STDOUT.

Try adding 

    ...
    } elsif (defined $pid) {    # child does
      close STDOUT;             # so parent can go on
      close STDERR;  # <--- THIS
      ...

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(The open STDERR, ">&=1"; which you find in merlyn's code doesn't implicitly close file descriptor number 2 (stderr) under the hood ... as you can verify using strace. )

The fact that it (seemingly) works with Safari probably has to do with different browser buffering behavior, i.e. it presumably processes partial content differently (before the HTTP request has completed). But that's just a guess — at the moment I don't have a Safari to investigate this further.  (You could check whether the individual Apache children (CGI processes) actually do terminate as expected in this case...)

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Re^2: Problem w/ forking CGI script
by tlm (Prior) on Oct 03, 2008 at 16:20 UTC

    Thanks for the tip. That's good to know in general.

    The way I ultimately solved the problem was to examine the requests generated by both Safari and Firefox. One important difference was that Firefox was sending a "Keep-Alive: 300" header, while Safari wasn't. This gave me the idea of modifying the redirection to 

        print redirect( -Location => self_url(), -Connection => 'close' );

    [download]
    This worked.

    But your suggestion of closing STDERR also works. I'll do both from now on, for good measure. :-)

    the lowliest monk

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