Re: How to get Apache to use simultaneous connections to my fcgi app?

Sebastian Böhm <[email protected]> Tue, 21 Aug 2007 04:06:14 +0200
Newsgroups	gmane.comp.web.fastcgi.devel,gmane.spam.detected
Message-ID	<[email protected]>
Am 21.08.2007 um 03:28 schrieb joe-QzMH92Wc/[email protected]:

> On Aug 20, 2007, at 21:08 UTC, Bo Lindbergh wrote:
>
>> You may find `grep -w FCGI_GET_VALUES mod_fastcgi-2.4.2/*.c`
>> illuminating.
>>
>> In short, the only way to handle multiple requests simultaneously
>> with mod_fastcgi is to have it start multiple instances of your
>> application.
>
> Doh!  And in external mode, it doesn't start any instances of your
> application.  I'm using external mode because it's the only way I can
> find to make mod_fastcgi to use TCP sockets, rather than Unix sockets
> (which I don't have easy access to in my environment).

this is correct: you can use tcp only with external mode (this is a  
mod_fastcgi limitation, rather than a limitation of the fastcgi spec)


>
> So, is it the case that mod_fastcgi can only make multiple requests
> simultaneously for local apps communicating over Unix sockets?
>
> If so, that seems like a pretty severe limitation -- even if you app
> speaks Unix sockets, what if you want to run it on another machine for
> load-balancing?  If it can only get one request at a time, that's  
> going
> to wipe out most of the benefit of the external server, isn't it?


I modified the script to act as an external server and it worked.
This is how i configured it in apache : "FastCgiExternalServer /opt/ 
apache/htdocs/test123.fcpl -host 10.211.55.4:8888 -flush"
I did run the script on a differed machine. The "-flush" might be  
important depending on what you actually do.

Although I run only one instance of the script I could verify that it  
processed multiple requests at the same time.
The response this script created takes 10 seconds, printing one line  
every second, it could see the response line-by-line in two browser  
windows.

#!/usr/bin/perl

exit() if fork();
close stdin;
close stdout;
close stderr;

use strict;
use FCGI;
use Fcntl;
use POSIX qw(:errno_h);
use IO::Handle;

my $socker = FCGI::Opensocket(":8888",15);


my @fcgihandles = ();

for(1..10)
{
     push @fcgihandles,create_fcgi_handle($_)
}


while(1)
{

     # wait one second for new request
     my $rbits = '';
     vec( $rbits, 0 , 1 ) = 1; #fcgi socket has fileno 0
     my $nfound = select ($rbits, undef, undef, 1);

     # if there is a new connection accept it
     if($nfound >0)
     {
         foreach my $handle (@fcgihandles)
         {
             next if $handle->{'status'} ne 'available';

             if($handle->{'req'}->Accept() >= 0)
             {
                 my $out = $handle->{'out'};
                 print $out "Content-type: text/html\r\n\r 
\n<html><body>BEGIN ".$handle->{'id'}."<br/>\r\n";
                 $handle->{'req'}->Flush();
                 $handle->{'counter'}=1;
                 $handle->{'status'}='accepted';
                 last;
             }
             else
             {
                 warn 'under which circumstances does this happen?';
             }
         }
     }


     foreach my $handle (@fcgihandles)
     {
         next if $handle->{'status'} ne 'accepted';

         my $out = $handle->{'out'};

         print $out "line:".$handle->{'counter'}."<br/>\r\n";
         $handle->{'req'}->Flush();
         $handle->{'counter'}++;
         if($handle->{'counter'}==10)
         {
             print $out "finished </body></html>\r\n";
             $handle->{'req'}->Flush();
             $handle->{'req'}->Finish();
             $handle->{'status'}='available';
         }
     }
}



sub create_fcgi_handle($)
{
     my $id = shift;

     my %data = ();

     my %env = ();
     my $in = new IO::Handle;
     my $out = new IO::Handle;
     my $err = new IO::Handle;

     my $req = FCGI::Request($in,$out,$err, \%env,$socket);

     $in->autoflush(1);
     $out->autoflush(1);
     $out->autoflush(1);

     $data{'id'} = $id;
     $data{'in'} = $in;
     $data{'out'} = $out;
     $data{'err'} = $err;
     $data{'env'} = \%env;
     $data{'req'} = $req;
     $data{'status'} = 'available';

     return \%data;

}


>
> Thanks,
> - Joe
>
> --
> Joe Strout -- joe-QzMH92Wc/[email protected]
> Strout Custom Solutions, LLC
>
> ___________________________________
> fastcgi-developers mailing list
> http://fastcgi.com/fastcgi-developers/
>

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