I can't speak to your exact situation, but for what it's worth... In Plack environments, I use IPC::Open3. In mod_perl environments, I use Apache2::SubProcess.
If you have a Apache2::RequestRec object, you can then do something like this: ($child_in, $child_out, $child_err) = $r->spawn_proc_prog($script,$script_args); (I have a particular context with an older Catalyst where I had to use a custom PSGI middleware to save the Apache2::RequestRec object for later reuse, as POST/PUT requests were discarding it, but where there's a will there's a way...) I don't know if I'd choose mod_perl for a new project, but I still use it for some older ones and it's pretty good. David Cook Senior Software Engineer Prosentient Systems -----Original Message----- From: Steven Haigh via modperl <modperl@perl.apache.org> Sent: Tuesday, 14 May 2024 2:45 PM To: modperl@perl.apache.org Subject: Re: stdout from scripts goes to apache logs On 14/5/24 14:18, Ed Sabol wrote: > On May 13, 2024, at 11:00 PM, Steven Haigh via modperl > <modperl@perl.apache.org> wrote: >> If I was to guess, it seems like an interaction with open3 and modperl. >> >> https://perldoc.perl.org/IPC::Open3 > > Yes, this is a known problem with IPC::Open3 that is commonly seen > with mod_perl. It's been a Perl bug since 2009, and nobody has > apparently been interested in fixing it. :( > > https://github.com/Perl/perl5/issues/9759 Damn, that's interesting to find out... and annoying :) > So I think you just need to work around it. I recommend not using IPC::Open3 > in any mod_perl projects. I typically just use backticks and redirect stderr > to stdout or to a temp file, but sometimes you just need separate > filehandles. For that, I offer the following potential workarounds that you > can try: > > (1) Use IPC::Run instead of IPC::Open3. I've seen at least one report that > says that IPC::Run works well in mod_perl, and it can do similar things. > > https://metacpan.org/pod/IPC::Run I did have some success with IPC::Run - and that does seem to work as expected - however I hit buffering issues that I didn't see when using the open3 code. One of the tools I use this code with is a looking glass - so you can perform traceroutes to various places. With using cgi-script + open3, this is returned line by line to the browser - which is really nice. Using IPC::Run, you get no output until the traceroute has completed. I haven't spent a ton of time to see if that buffering can be altered in IPC::Run as yet, but either way, it becomes a less-optimal result to just blat the entire traceroute to the screen at once. It can take quite a while for a traceroute to complete if theres 20+ hops that don't respond - which means you get no output at all until its done. > (2) Re-jigger the file descriptors as shown here: > > https://stackoverflow.com/questions/2097247/ipcopen3-fails-running-und > er-apache/24311232#24311232 I did try this, but the output still went to the apache logs. For the traceroute example, I tried this code: my $cmd = "/usr/bin/stdbuf"; my @args = qw@ -o1 -e1 /usr/bin/traceroute @; if ( $vars->{'type'} eq "ipv6" ) { push @args,"-6"; } else { push @args,"-4"; } push @args, $vars->{"host"}; print '<pre class="alert">'; my ($save_stdin,$save_stdout); open $save_stdin, '>&STDIN'; open $save_stdout, '>&STDOUT'; open STDIN, '>&=0'; open STDOUT, '>&=1'; my $pid = open3(0, (my $pipe = gensym), 0, $cmd, @args); while ( my $output = <$pipe> ) { print $output; } close(STDIN); close(STDOUT); open STDIN, '>&', $save_stdin; open STDOUT, '>&', $save_stdout; print "Trace Complete</pre>"; This still printed the output to the apache logs, along with an error: Warning: unable to close filehandle $save_stdin properly: at /var/www/html/lg/index.pl line 66. I'm starting to wonder that if with the various 'strange' behaviours, it might be easier to not use mod_perl for this and keep using the cgi-script handler. It isn't a high performance or popular site at all - I've been using it more as a learning exercise - but I'm wondering if the benefits of using mod_perl here are purely academic :) -- Steven Haigh 📧 net...@crc.id.au 💻 https://crc.id.au
