CODEWITHSUNDEEP
linuxperlapache2mod-perl2mod-perl-registry
Severun
Severun

Reputation: 2916

Proc::Daemon with mod_perl does not write STDOUT or STDERR

I have am using Proc::Daemon in a mod_perl script thusly:

$bindir, $ddir are executable/logfile locations and $jid is a unique per process identifier (to avoid having the same file open by multiple processes). $cmd is loaded with arbitrary perl scripts and arguments.

   my $daemon = Proc::Daemon->new (
            work_dir        => $bindir,
            child_STDOUT    => $ddir.'/'.$jid.'_stdout.log',
            child_STDERR    => $ddir.'/'.$jid.'_stderr.log',
            pid_file        => $ddir.'/'.$jid.'_pid.txt',
            exec_command => $cmd,
    );

    my $pid = $daemon->Init();

The above works fine when using Apache with cgi-script (no mod_perl). In the "$cmd" process, print and print STDERR log to the above defined log files.

When I run the above using mod_perl2, on Ubuntu Linux 14.04 LTS, using Apache2 The pid file gets written with the PID and the above log files are created, but nothing is ever written to the log files. I am able to open new files descriptors within $cmd and write to them, but under mod_perl, it is not sending output to the child_STDOUT and child_STDERR files.

I think I am missing something really obvious. Has anyone else seen this before, and or have any suggestions in getting this to work in mod_perl.

Additional info Using the mpm_prefork module in Apache

Relevant Apache Config

    <Files "*.pl">
            # SetHandler cgi-script # It works if I use cgi-script
            SetHandler perl-script
            PerlOptions -SetupEnv # Tried with and without this
            # PerlHandler ModPerl::RegistryPrefork # Using this made no difference
            PerlHandler ModPerl::Registry

    </Files>

Upvotes: 0

Views: 382

Answers (1)

Severun
Severun

Reputation: 2916

OK so there were so many solutions that did not work This is what I wound up doing. I created a script called launchjob.pl:

#!/usr/bin/perl -w

use strict;
use warnings;

use POSIX 'setsid';
use Proc::Daemon;

my $bindir = $ARGV[0];
my $ddir = $ARGV[1];
my $jid = $ARGV[2];
my $cmd = $ARGV[3];

setsid or die "Cannot start a new session: $!";

my $daemon = Proc::Daemon->new (
                work_dir        => $bindir,
                child_STDOUT    => $ddir.'/'.$jid.'_stdout.log',
                child_STDERR    => $ddir.'/'.$jid.'_stderr.log',
                pid_file        => $ddir.'/'.$jid.'_pid.txt',
                exec_command => $cmd,
             );

my $pid = $daemon->Init();

exit 1;

I replaced the code, in the mainline, where I was calling Proc::Daemon with the following:

The following did not work. Proc::Daemon gave me an sh: No such file or directory error.

system('launchjob.pl', $bindir, $ddir, $jid, $cmd);

Instead I used the following which seems to run as expected.

use IPC::Run3; run3("launchjob.pl ".$bindir." ".$ddir." ".$jid." ".$cmd);

This seems to have fixed it right up.

Upvotes: 0

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