# Incomplete, missing or invalid response headers

**URL:** <https://www.ruby-forum.com/t/incomplete-missing-or-invalid-response-headers/176848>\
**Category:** Mongrel\
**Created:** [October 7, 2009, 1:13am UTC](https://www.ruby-forum.com/t/incomplete-missing-or-invalid-response-headers/176848 "2009-10-07T01:13:40Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![killswitchcollectiv](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/b5ac83/32.png) [@killswitchcollectiv](https://www.ruby-forum.com/u/killswitchcollectiv)\
**Post date:** [October 7, 2009, 1:13am UTC](https://www.ruby-forum.com/t/incomplete-missing-or-invalid-response-headers/176848/1 "2009-10-07T01:13:40Z")

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We have been using nginx in combination with 3 mongrel instances on our  
servers. Recently we began testing the use of haproxy to act as a middle  
man  
to more efficiently handle our queues. When nginx was talking directly  
with  
our mongrels we had no issues, but now with haproxy we do seem to be  
experiencing some 502 errors. We monitor our mongrels using monit and  
when a  
mongrel instance begins to take up too large of a memory footprint we  
have  
monit restart the mongrel instance. It appears that the 502 errors are  
thrown on the last request that the mongrel handles prior to restarting  
(this is how it appears, but we can’t be certain this is correct). The  
log  
from haproxy seems to imply that it was waiting for “complete, valid  
response HEADERS from the server” when it throws the 502 error. Is it  
possible that the mongrel headers are sent back differently on the last  
request prior to a restart? We do know that the last request is being  
processed because a user was trying to create a record and received a  
502,  
but found that it did successfully create the record, so the problem  
seems  
to be solely in the response headers after the request has been  
processed.

If you are interested you can see the breakdown of the haproxy error  
here:

[http://pastie.org/private/nfvbtq236x8jp9ynj4dg](http://pastie.org/private/nfvbtq236x8jp9ynj4dg)

I don’t know if this is an issue with haproxy or with mongrel so I have  
also  
asked the folks at haproxy to look at the issue.

Any insight you can offer from the mongrel point of view would be  
greatly  
appreciated. Thanks!

Ben F.