# Timeout issue and custom solution

**URL:** <https://www.ruby-forum.com/t/timeout-issue-and-custom-solution/176308>\
**Category:** Rails\
**Created:** [September 28, 2009, 10:43pm UTC](https://www.ruby-forum.com/t/timeout-issue-and-custom-solution/176308 "2009-09-28T22:43:20Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![zatta105](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/ce7236/32.png) [@zatta105](https://www.ruby-forum.com/u/zatta105)\
**Post date:** [September 28, 2009, 10:43pm UTC](https://www.ruby-forum.com/t/timeout-issue-and-custom-solution/176308/1 "2009-09-28T22:43:20Z")

</div>

We’re using nginx with HAProxy and mongrel as well as monit and we’re  
integrating with SAP using Piers H.'s sapnwrfc gem. It contains a  
C-extension which calls itself an SAP provided C-library for RFC  
calls. In general it works great.

But there are SAP RFCs with very long runtimes, e.g. orders with a lot  
of items, searches with not restricted enough search criterias, but  
also sporadic hickups in SAP which can happen to any RFC call. They  
can block a mongrel for more than 2 minutes. We therefore need a  
timeout solution.

The 2 available solutions we found (SystemTimer and Terminator) just  
wouldn’t work, no matter what we tried. We therefore wrote an old-  
fashioned custom solution: each request writes a file initially and  
deletes it again at the end of processing. A monit process which runs  
periodically (in our case every 10s) checks whether there are any  
files older than a specific timeout period. If it finds one, it kills  
the mongrel process (no soft kill) and starts a new one. When the  
mongrel gets killed, nginx receives a 504 error. We assume that this  
will happen mostly (only ?) in timeout cases, therefore we modified it  
to redirect to our app to a page which has an error message about the  
timeout.

This solution works perfectly so far. The only weird phenomenon we saw  
is that in one case the user never gets the error page/redirect, but  
the browser just hangs (firefox and IE).

Comments ? Ideas why SytemTimer and Terminator would not work ?  
Improvements to the current solution ?

Adrian Z.  
[www.b2b2dot0.com](http://www.b2b2dot0.com)

The solution details:

1. Setting a global constant with the mongrel port during  
initialization:  
begin  
ObjectSpace.each\_object(Mongrel::HttpServer) do |i|  
Const::App.port = i.port  
end  
rescue  
Const::App.port = ‘3000’ # when testing etc.  
end

2. Creating/deleting the file in before/after filters:  
class ApplicationController \< ActionController::Base  
before\_filter :write\_timeout\_file  
after\_filter :delete\_timeout\_file  
def write\_timeout\_file  
File.new(“tmp/pids/mongrel.#{Const::App.port}.req”, “w”).close  
end  
def delete\_timeout\_file  
File.delete(“tmp/pids/mongrel.#{Const::App.port}.req”)  
end  
end

3. Monit Configuration:  
check file mongrel.3000.req path /var/www/apps/b2b2dot0/current/tmp/  
pid /mongrel.3000.req  
if timestamp \> 90 seconds  
then exec “/export/admin-scripts/kill\_mongrel.sh 3000”  
mode passive  
group mongrel\_timeout

---

<div class="post-metadata">

**Author:** ![zatta105](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/z/ce7236/32.png) [@zatta105](https://www.ruby-forum.com/u/zatta105)\
**Post date:** [September 29, 2009, 8:12am UTC](https://www.ruby-forum.com/t/timeout-issue-and-custom-solution/176308/2 "2009-09-29T08:12:24Z")

</div>

On Tue, Sep 29, 2009 at 12:21 AM, Adrian Z. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> timeout solution.
> 
> The 2 available solutions we found (SystemTimer and Terminator) just  
> wouldn’t work, no matter what we tried.

I too faced the same problem. I could use SystemTimer to timeout rails  
requests which did most any tasks like running a system command via  
%x[], or  
sleeping for some time etc, but AR queries to postgresql weren’t timed  
out.  
That’s when I monkey patched the AR postgresql connection adapter to set  
a  
session “statement\_timeout” for postgres. Now postgres times out any  
query  
running for longer than my timeout milli seconds value.

I guess you could do the same with whatever DB or backend service you’re  
using. Of course, the pure solution would be to find out why SystemTimer  
wouldn’t work in this case and fix SystemTimer or rails or both  
depending on  
the problem.

cheers,  
skar.