[Catalyst] Running system commands under FastCGI with IPC::Cmd / IPC::Run

[heidi brandenburg]

I've run into this problem with FCGI too. Our solution at the time, since the fileno call was in an internal API, was to skip it when STDOUT was tied. Getting an updated FCGI instead sounds like a happier thing.

I notice this in current FCGI comments:

# Some things (e.g. IPC::Run) use fileno to determine if a filehandle is open,
# so we return a defined, but meaningless value. (-1 being the error return
# value from the syscall in c, meaning it can never be a valid fd no)
# Probably a better alternative would be to return the fcgi stream fd.
sub FILENO { -1 }


On Oct 21, 2010, at 12:29 PM, Stuart Watt wrote:

> You may want to check your version of FCGI. There are previous reports of related issues, which seem to be an interaction between IPC::*  modules expectations of standard input/output/error, and FCGI, which fakes them. See http://www.mail-archive.com/ports@openbsd.org/msg16948.html for an example. In my FCGI, the FILENO method is present, but this appears to have been added in version 0.67_01 on 20 Dec 2009 - this is pretty recent and your Perl may not include it.
> 
> --S
> 
> Stuart Watt
> ARM Product Developer
> Information Balance
> 
> 
> On 10/21/2010 2:43 PM, Ian Sillitoe wrote:
>> 
>> I have a Catalyst model that runs a system command as part of a search facility. The system call only takes a fraction of a second so is processed inline and this all works fine when tested outside of Catalyst and when called under the Catalyst standalone server. However, when I deploy it to my FastCGI environment I have problems - everything seems to work fine apart from the results of the system call.
>> 
>> The system call is (give or take):
>> 
>>     IPC::Cmd::run(
>>             command => [qw/ blastall -d sequences.db -i input.fa -o output.results /], 
>>             verbose => 0,
>>             timeout => 10,
>>         );
>> 
>> When run under the test server the file 'output.results' contains the results of the search:
>> 
>> gi|5524211|gb|AAD441661|        pdb|3cx5C00     45.26   285     154     1       1       283     91      375     4e-73    267
>> gi|5524211|gb|AAD441661|        pdb|2e74A00     33.33   99      65      1       21      118     117     215     9e-16   77.0
>> gi|5524211|gb|AAD441661|        pdb|2ih2A01     34.78   23      15      0       115     137     85      107     4.0     25.0
>> ...
>> 
>> When the same application is being run under FastCGI the file is created but is empty.
>> 
>> The system call was originally being wrapped with IPC::Cmd (via MooseX::Role::Cmd). I checked what happened when I explicitly used IPC::Run
>> 
>>     my ($in, $out, $err);
>>     my $success = IPC::Run::run [qw/ blastall -d sequences.db -i input.fa -o output.results /], \$in, \$out, \$err, IPC::Run::timeout( 10 );
>> 
>> This works under the test server, but throws the following error under FastCGI:
>> 
>> "Can't locate object method "FILENO" via package "FCGI::Stream" at /home/ian/perl5/lib/perl5/IPC/Run.pm line 1115.
>> 
>> 
>> 
>> If I bypass IPC::* and run the system command with backticks then it seems to work fine under both the test server and FastCGI. However the system call is happening a long way away from Catalyst - I don't really want to hard code this with backticks just to get it working under FastCGI.
>> 
>> There seems to be a few different things going on here - I'm not sure exactly where the problem lies or what might be a red herring - would be grateful if anyone can help point me in the right direction.
>> 
>> Cheers,
>> 
>> Ian
>> 
>> 
>> 
>> 
>> Running FastCGI server on my desktop on port 3001:
>> 
>>   script/my_app_fastcgi.pl -l bsmlx53:3001 -n 3 -p my-app.pid -d
>> 
>> Forwarding requests there from external facing server with the following config:
>> 
>>   <VirtualHost *:80>
>>     ServerName      test.foo.com
>>     DocumentRoot    /home/ian/My-App/trunk/
>>     ErrorLog        logs/test.foo.com-error_log
>> 
>>     FastCgiExternalServer   /tmp/my-app.fcgi -host bsmlx53:3001  
>> 
>>     Alias           /static /home/ian/My-App/trunk/root/static
>>     Alias           /       /tmp/my-app.fcgi/
>>   </VirtualHost>
>> 
>> Modules:
>> 
>>   Catalyst::Runtime (5.80029)
>>   IPC::Run (0.89)
>>   FCGI (0.67)
>> 
>> 
>> 
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