[Glass] How to deal with timeouts, fastcgi and what is the expected behavior?

[Mariano Martinez Peck]

Hi guys,

I have a strange situation with timeouts under nginx/fastCGI and I am not
sure what is expected. I am executing a Seaside WATask, where one of its
method takes (for sure) more then the timeout of nginx/fastCGI. My piece of
nginx setup is something like this:

location @seasidemariano {
 include fastcgi_params;
fastcgi_param REQUEST_URI $uri?$args;
  fastcgi_pass seasidemariano;
 fastcgi_connect_timeout      180;
      fastcgi_send_timeout         180;
      fastcgi_read_timeout         180;

  fastcgi_next_upstream error invalid_header timeout http_500;
}


So...as you can see I have a timeout of 180 and I tell to go to the next
upstream (gem) in any error, including timeout. Now...say I have this
method being executed and it takes more than 180 seconds. What happens is
that the user gets a Nginx 504 Gateway Time-out in the browser. Ok. But...
I have some questions:

1) what happens with that gem that was executing the task (the one that
took more than 180)? is the execution finished even if the nginx give a
timeout and pass the reuqest to the next gem? Or the gem execution is
aborted?  Why I ask? Because...I out a log to a file inside my method...and
it looks like if the method were called 3 times rather than 1. And from a
domain point of view.... it is not good that such a method is executed 3
times...

2) If I put a larger timeout...say 1500 ... it works correct..the method is
executed only once, no timeout. Same if I use swazoo. So it is something to
do with the timeouts and fastCGI for sure.

3) 3 times...why? It seems because I have 3 gems. I did an experiment, and
I set only 2 gems to nginx fastcgi. And yes, the method was executed only 2
times rather than 3.

So....how do people normally deal with this? Of course, the immediate
workaround seems to increase the timeout...but it seems risky to me,
thinking that if for some reason (like GC running or whatever) one
particular request takes more than the timeout, then my "backend code"
could be run more than once...

Thanks in advance,

-- 
Mariano
http://marianopeck.wordpress.com
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