499 errors

[Nick Tidey]

We have a Rails app with nginx proxying requests to 2 mongrel servers. I'm seeing a lot of 499 errors crop up, for example:

lodgeit.aioi.local-access.log-20100603:192.168.0.50 - - [02/Jun/2010:09:32:39 +1000] "GET /?page=61 HTTP/1.1" 499 0 "http://lodgeit/?page=57" "Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7 (.NET CLR 3.5.30729)"
lodgeit.aioi.local-access.log-20100603:192.168.0.50 - - [02/Jun/2010:09:32:39 +1000] "GET /?page=61 HTTP/1.1" 499 0 "http://lodgeit/?page=57" "Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7 (.NET CLR 3.5.30729)"
lodgeit.aioi.local-access.log-20100603:192.168.0.50 - - [02/Jun/2010:09:32:39 +1000] "GET /?page=61 HTTP/1.1" 499 0 "http://lodgeit/?page=57" "Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7 (.NET CLR 3.5.30729)"
lodgeit.aioi.local-access.log-20100603:192.168.0.50 - - [02/Jun/2010:09:32:40 +1000] "GET /?page=61 HTTP/1.1" 499 0 "http://lodgeit/?page=57" "Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7 (.NET CLR 3.5.30729)"
lodgeit.aioi.local-access.log-20100603:192.168.0.50 - - [02/Jun/2010:09:32:40 +1000] "GET /?page=61 HTTP/1.1" 499 0 "http://lodgeit/?page=57" "Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7 (.NET CLR 3.5.30729)"
lodgeit.aioi.local-access.log-20100603:192.168.0.50 - - [02/Jun/2010:09:32:40 +1000] "GET /?page=61 HTTP/1.1" 499 0 "http://lodgeit/?page=57" "Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7 (.NET CLR 3.5.30729)"
lodgeit.aioi.local-access.log-20100603:192.168.0.50 - - [02/Jun/2010:09:32:40 +1000] "GET /?page=61 HTTP/1.1" 499 0 "http://lodgeit/?page=57" "Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7 (.NET CLR 3.5.30729)"
lodgeit.aioi.local-access.log-20100603-192.168.0.50 - - [02/Jun/2010:09:32:42 +1000] "GET /?page=61 HTTP/1.1" 200 13763 "http://lodgeit/?page=57" "Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US; rv:1.9.1.7) Gecko/20091221 Firefox/3.5.7 (.NET CLR 3.5.30729)"

I understand the 499 error is because of the client closing the connection before nginx can send the response. I hope someone more technical than me can explain what might be causing 7 GETs in the space of one second. Users are using Firefox. I wonder if Firefox might be causing this behaviour?

Thanks in advance
Nick
--