如何使用Perl FCGI杀死我？

Question

I'm having a little problem with nginx and the Perl FCGI module. I have a long operation in my FCGI program that may outlive the server (or the user on the server) on the other end of the Unix socket I'm using to communicate FCGI. I need the FCGI accept() loop in my program to break if the FCGI request is closed. I tried installing INT, TERM, etc signal handlers, but they do nothing, since the only communication between nginx and my program happens over the FCGI socket, AFAIK.

I also tried this but there's no way that I can see to use the FCGI module in Perl to send raw data to or from nginx over the FCGI socket. Is there a way I can do it without modifying the FCGI module to have a "ping" function?

The basic problem is that my program does not know if nginx has terminated the FCGI request.

Example:

#!/usr/bin/perl -w
use strict;
use FCGI;

my $fcgi_socket = FCGI::OpenSocket( '/tmp/test.socket', 100000 );
my $request = FCGI::Request(\*STDIN, \*STDOUT, \*STDERR, \%ENV, $fcgi_socket);
REQUEST: while($request->Accept() >= 0) {
    #begin handling request
    my $result = '';
    while (1) { #or select(), etc
        if (somehow check whether the fcgi $request is still live) {
            next REQUEST;
        }
        #check for results, set $result if done
    }
    print $result;
}

Answer 1

You have to use a FCGI implementation which treats FCGI_ABORT_REQUEST .

You cannot use the following, because they ignore FCGI_ABORT_REQUEST :

• FCGI <=v0.69 (the one which you are currently using?)
• FCGI-Async <=v0.19
• Net-FastCGI <=v0.08
• FCGI-EV <=1.0.7

You could use the following, which treat FCGI_ABORT_REQUEST :

• Vitaly Kramskikh's AnyEvent-FCGI

When using AnyEvent-FCGI , checking for an aborted request is as easy as calling $request->is_active() , but keep in mind that is_active() will not reflect the true state of the request until the on_request handler returns, which means you have to return from on_request as soon as possible and somehow do the actual work "in parallel" (you probably don't want to use Perl threads , but something more akin to continuations ) in order to give the AnyEvent loop the opportunity to process any further requests (including FCGI_ABORT_REQUEST s) while you are completing the long-winded operations.

I am not familiar enough with AnyEvent to know for sure whether there is a better way of doing this, but here's my take, below, for a start:

use AnyEvent;
use AnyEvent::FCGI;

my @jobs;
my $process_jobs_watcher;

sub process_jobs {
  # cancel aborted jobs
  @jobs = grep {
    if ($_->[0]->is_active) {
      true
    } else {
      # perform any job cleanup
      false
    }
  } @jobs;
  # any jobs left?
  if (scalar(@jobs)) {
    my $job = $jobs[0];
    my ( $job_request, $job_state ) = @$job;
    # process another chunk of $job
    #  if job is done, remove (shift) from @jobs
  } else {
    # all jobs done; go to sleep until next job request
    undef $process_jobs_watcher;
  }
}

my $fcgi = new AnyEvent::FCGI(
  port => 9000,
  on_request => sub {
    my $request = shift;
    if (scalar(@jobs) < 5) { # set your own limit
      # accept request and send back headers, HTTP status etc.
      $request.print_stdout("Content-Type: text/plain\nStatus: 200 OK\n\n");
      # This will hold your job state; can also use Continutiy
      #  http://continuity.tlt42.org/
      my $job_state = ...;
      # Enqueue job for parallel processing:
      push @jobs, [ $request, $job_state ];
      if (!$process_jobs_watcher) {
        # If and only if AnyEvent->idle() does not work,
        #  use AnyEvent->timer() and renew from process_jobs
        $process_jobs_watcher = AnyEvent->idle(cb => \&process_jobs);
      }
    } else {
      # refuse request
      $request.print_stdout("Content-Type: text/plain\nStatus: 503 Service Unavailable\n\nBusy!");
    }
  }
);

AnyEvent->loop;