# Response stalls with gzip and proxy

**URL:** <https://www.ruby-forum.com/t/response-stalls-with-gzip-and-proxy/225215>\
**Category:** NGINX\
**Created:** [December 20, 2012, 8:06pm UTC](https://www.ruby-forum.com/t/response-stalls-with-gzip-and-proxy/225215 "2012-12-20T20:06:00Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![aris](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/258eb7/32.png) [@aris](https://www.ruby-forum.com/u/aris)\
**Post date:** [December 20, 2012, 8:06pm UTC](https://www.ruby-forum.com/t/response-stalls-with-gzip-and-proxy/225215/1 "2012-12-20T20:06:00Z")

</div>

We’ve been experiencing a weird issue with nginx used as a gzipping  
proxy.  
One of our internal services doesn’t support content-encoding and  
because it  
usually streams huge amounts of json data in response, we’ve decided to  
put  
it behind nginx. Unfortunately, about 5-10% of responses in this  
configuration seem to just stall with the TCP connection perfectly fine,  
but  
no data going anywhere.

I’ve tried to diagnose the issue to check if it’s a problem with our  
HTTP  
libraries, VPN or network, but it does look like nginx is the culprit:

- The issue is reproducible with any HTTP client, including curl  
–compress.
- Packet capture on the server that’s hosting a client and the server  
that’s hosting nginx show nothing interesting. There are no lost or  
corrupted packets; the client receives the last packet sent by nginx,  
ACKs  
it and then ACKs keepalives. If the client is killed, it and nginx  
exchange  
FIN/FIN-ACKs just fine.
- Packet capture on the loopback interface, however, shows that nginx  
just  
stops reading data at some point (I see a “full window” notice in  
wireshark  
and netstat shows an nginx worker sitting with a 512k-2M receive queue  
with  
an empty transmit queue).

Some technical details (I’ve masked our internal host names):

The server on which nginx is on is running a server build of Ubuntu;  
uname  
-a gives Linux 3.2.0-32-generic #51-Ubuntu SMP Wed Sep 26  
21:33:09 UTC 2012 x86\_64 x86\_64 x86\_64 GNU/Linux. This issue occurs on  
nginx  
from the Ubuntu repo (1.1.19-1ubuntu0.1) and Debian wheezy repo  
(1.2.1-2.2).

nginx -V output:  
nginx version: nginx/1.2.1  
TLS SNI support enabled  
configure arguments: --prefix=/etc/nginx  
–conf-path=/etc/nginx/nginx.conf  
–error-log-path=/var/log/nginx/error.log  
–http-client-body-temp-path=/var/lib/nginx/body  
–http-fastcgi-temp-path=/var/lib/nginx/fastcgi  
–http-log-path=/var/log/nginx/access.log  
–http-proxy-temp-path=/var/lib/nginx/proxy  
–http-scgi-temp-path=/var/lib/nginx/scgi  
–http-uwsgi-temp-path=/var/lib/nginx/uwsgi  
–lock-path=/var/lock/nginx.lock  
–pid-path=/var/run/nginx.pid --with-pcre-jit --with-debug  
–with-http\_addition\_module --with-http\_dav\_module  
–with-http\_geoip\_module  
–with-http\_gzip\_static\_module --with-http\_image\_filter\_module  
–with-http\_realip\_module --with-http\_stub\_status\_module  
–with-http\_ssl\_module --with-http\_sub\_module --with-http\_xslt\_module  
–with-ipv6 --with-sha1=/usr/include/openssl  
–with-md5=/usr/include/openssl  
–with-mail --with-mail\_ssl\_module  
–add-module=/tmp/buildd/nginx-1.2.1/debian/modules/nginx-auth-pam  
–add-module=/tmp/buildd/nginx-1.2.1/debian/modules/nginx-echo  
–add-module=/tmp/buildd/nginx-1.2.1/debian/modules/nginx-upstream-fair  
–add-module=/tmp/buildd/nginx-1.2.1/debian/modules/nginx-dav-ext-module

Basic nginx config is unchanged from Ubuntu-provided defaults; the  
server  
section looks like this:

```
server {
    gzip on;
    gzip_proxied any;
    gzip_types application/json;

    listen 80 default;
    server_name <servername>;

    access_log /var/log/nginx/<servername>-access.log;

    location / {
        proxy_pass http://127.0.0.1:8083;
        proxy_buffering off;
    }
}

```

You can see the nginx debug log here: [nginx response stall - Pastebin.com](http://pastebin.com/qDis2RS4) (I’ve  
masked the request URL but it’s otherwise unchanged); it ends about 1  
second  
after the response stall.

Posted at Nginx Forum:

> **[Response stalls with gzip and proxy](https://forum.nginx.org/read.php?2,234275,234275#msg-234275)**
>
> We've been experiencing a weird issue with nginx used as a gzipping proxy. One of our internal services doesn't support content-encoding and because it usually streams huge amounts of json data in response, we've decided to put it behind nginx....