# Question: http video streaming and nginx ram usage

**URL:** <https://www.ruby-forum.com/t/question-http-video-streaming-and-nginx-ram-usage/204224>\
**Category:** NGINX\
**Created:** [March 8, 2011, 6:16am UTC](https://www.ruby-forum.com/t/question-http-video-streaming-and-nginx-ram-usage/204224 "2011-03-08T06:16:51Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![luislavena](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/l/0ea827/32.png) [@luislavena](https://www.ruby-forum.com/u/luislavena)\
**Post date:** [March 8, 2011, 6:16am UTC](https://www.ruby-forum.com/t/question-http-video-streaming-and-nginx-ram-usage/204224/1 "2011-03-08T06:16:51Z")

</div>

Hi everyone,

I’m using Nginx to forward incoming http requests (from the Internet) to  
an Aviosys 9100A+ (low-cost) IP video server.

My Nginx 0.7.64 runs on a small embedded linux device under OpenWRT -  
the device has only 13 MB of  
free ram when nginx is loaded. The user’s http requests get forwarded to  
nginx on the OpenWRT box, and nginx  
reverse proxies the requests on to the video server over LAN.

The job of nginx is to prevent people on the Internet from changing the  
settings of the video server via the http interface - only viewing of  
the streams should be allowed! Therefore, nginx acts as a reverse-proxy  
and forwards only the allowed URL on to the server. So the viewers of  
the stream cannot change the video server’s settings via the web  
interface, because my nginx config does not forward the “banned” URLs.

It is OK for me for now that e.g. 3 simultaneous viewers consume 3 times  
the bandwidth.

[ Just if you are wondering : It is not possible to set a password on  
the video server, since I can only disable authentication altogether. It  
is a low-cost device and configuration options are very limited. ]

Now here is where I get stuck:

This video server transfers the images to the viewing person’s web  
browser in one long http response in real-time.

As I wrote, In my setup, I reverse-proxy only the allowed URLs (i.e. the  
ones to “get the video”) on to the video server with nginx. This works  
fine, but nginx seems to buffer the http data that it forwards locally.  
So while viewing the video stream, nginx consumes more and more RAM  
until the little linux device crashes.

However, if I stop viewing the stream after 1 or 2 minutes, before RAM  
runs out, the memory gets freed again.  
I believe it frees the ram because the request is finished.

On a Linux PC server, it all works perfectly. But in order to save  
electricity, I would like to use the small linux device.

Has anyone got a hint for me what I could do to stop nginx from keeping  
the long request in RAM (this is what I think what happens, at least)?

Any help would be greatly appreciated!

Here is my nginx.conf. 192.168.3.46 Is the IP of the video server.

user root;  
worker\_processes 1;

#access\_log off;  
error\_log off;

#error\_log logs/error.log;  
#error\_log logs/error.log notice;  
#error\_log logs/error.log info;

#pid logs/nginx.pid;

events {  
worker\_connections 10;  
}

http {  
include mime.types;  
default\_type application/octet-stream;

```
#log_format main '$remote_addr - $remote_user [$time_local]

```

“$request” ’  
# '$status $body\_bytes\_sent “$http\_referer” ’  
# ‘“$http\_user\_agent” “$http\_x\_forwarded\_for”’;

```
#access_log logs/access.log main;

sendfile on;
#tcp_nopush on;

#keepalive_timeout 0;
keepalive_timeout 65;

proxy_buffering off;
proxy_buffer_size 4k;
proxy_buffers 10 4k;
proxy_max_temp_file_size 0;

client_body_buffer_size 4k;
client_header_buffer_size 1k;
client_max_body_size 4k;
large_client_header_buffers 1 1k;

#gzip on;

server {
    listen 80;
    server_name localhost;

    #charset koi8-r;

    #access_log logs/host.access.log main;

```

# location / {

# root html;

# index index.html index.htm;

# }

```
location /GetStatus.cgi?JsVar=sStatus {
        proxy_buffering off;
        proxy_ignore_client_abort off;
        proxy_intercept_errors on;
        proxy_next_upstream error timeout invalid_header;
        proxy_redirect off;
        proxy_set_header X-Host $http_host;

```

# proxy\_set\_header X-Forwarded-For $remote\_addr;

```
        proxy_connect_timeout 60;
        proxy_send_timeout 60;
        proxy_read_timeout 60;
        proxy_pass http://192.168.3.46/GetStatus.cgi?JsVar=sStatus;
    }
location /Simple/home.htm?IMG {
        proxy_buffering off;
        proxy_ignore_client_abort off;
        proxy_intercept_errors on;
        proxy_next_upstream error timeout invalid_header;
        proxy_redirect off;
        proxy_set_header X-Host $http_host;

```

# proxy\_set\_header X-Forwarded-For $remote\_addr;

```
        proxy_connect_timeout 60;
        proxy_send_timeout 60;
        proxy_read_timeout 60;
        proxy_pass http://192.168.3.46/Simple/home.htm?IMG;
    }
location /Simple/home.htm?ATV {
        proxy_buffering off;
        proxy_ignore_client_abort off;
        proxy_intercept_errors on;
        proxy_next_upstream error timeout invalid_header;
        proxy_redirect off;
        proxy_set_header X-Host $http_host;

```

# proxy\_set\_header X-Forwarded-For $remote\_addr;

```
        proxy_connect_timeout 60;
        proxy_send_timeout 60;
        proxy_read_timeout 60;
        proxy_pass http://192.168.3.46/Simple/home.htm?IMG;
    }

location /Simple/core.jar {
        proxy_buffering off;
        proxy_ignore_client_abort off;
        proxy_intercept_errors on;
        proxy_next_upstream error timeout invalid_header;
        proxy_redirect off;
        proxy_set_header X-Host $http_host;

```

# proxy\_set\_header X-Forwarded-For $remote\_addr;

```
        proxy_connect_timeout 60;
        proxy_send_timeout 60;
        proxy_read_timeout 60;
        proxy_pass http://192.168.3.46:80;
    }

location /Simple/home.htm {
        proxy_buffering off;
        proxy_ignore_client_abort off;
        proxy_intercept_errors on;
        proxy_next_upstream error timeout invalid_header;
        proxy_redirect off;
        proxy_set_header X-Host $http_host;

```

# proxy\_set\_header X-Forwarded-For $remote\_addr;

```
        proxy_connect_timeout 60;
        proxy_send_timeout 60;
        proxy_read_timeout 60;
        proxy_pass http://192.168.3.46/Simple/home.htm;
    }

location /GetData.cgi {
        proxy_buffering off;
        proxy_ignore_client_abort off;
        proxy_intercept_errors on;
        proxy_next_upstream error timeout invalid_header;
        proxy_redirect off;
        proxy_set_header X-Host $http_host;

```

# proxy\_set\_header X-Forwarded-For $remote\_addr;

```
        proxy_connect_timeout 60;
        proxy_send_timeout 60;
        proxy_read_timeout 60;
        proxy_pass http://192.168.3.46/GetData.cgi;
    }

location /GetStatus.cgi {
        proxy_buffering off;
        proxy_ignore_client_abort off;
        proxy_intercept_errors on;
        proxy_next_upstream error timeout invalid_header;
        proxy_redirect off;
        proxy_set_header X-Host $http_host;

```

# proxy\_set\_header X-Forwarded-For $remote\_addr;

```
        proxy_connect_timeout 60;
        proxy_send_timeout 60;
        proxy_read_timeout 60;
        proxy_pass http://192.168.3.46/GetStatus.cgi;
    }

location /Jpeg/ {
        proxy_buffering off;
        proxy_ignore_client_abort off;
        proxy_intercept_errors on;
        proxy_next_upstream error timeout invalid_header;
        proxy_redirect off;
        proxy_set_header X-Host $http_host;

```

# proxy\_set\_header X-Forwarded-For $remote\_addr;

```
        proxy_connect_timeout 60;
        proxy_send_timeout 60;
        proxy_read_timeout 60;
        proxy_pass http://192.168.3.46/Jpeg/;
    }

location /Simple/WinWebLite.cab {
        proxy_buffering off;
        proxy_ignore_client_abort off;
        proxy_intercept_errors on;
        proxy_next_upstream error timeout invalid_header;
        proxy_redirect off;
        proxy_set_header X-Host $http_host;

```

# proxy\_set\_header X-Forwarded-For $remote\_addr;

```
        proxy_connect_timeout 60;
        proxy_send_timeout 60;
        proxy_read_timeout 60;
        proxy_pass http://192.168.3.46/Simple/WinWebLite.cab;
    }
location /Simple/bg1.jpg {
        proxy_buffering off;
        proxy_ignore_client_abort off;
        proxy_intercept_errors on;
        proxy_next_upstream error timeout invalid_header;
        proxy_redirect off;
        proxy_set_header X-Host $http_host;

```

# proxy\_set\_header X-Forwarded-For $remote\_addr;

```
        proxy_connect_timeout 60;
        proxy_send_timeout 60;
        proxy_read_timeout 60;
        proxy_pass http://192.168.3.46/Simple/bg1.jpg;
    }

location /html/favicon.ico {
        proxy_buffering off;
        proxy_ignore_client_abort off;
        proxy_intercept_errors on;
        proxy_next_upstream error timeout invalid_header;
        proxy_redirect off;
        proxy_set_header X-Host $http_host;

```

# proxy\_set\_header X-Forwarded-For $remote\_addr;

```
        proxy_connect_timeout 60;
        proxy_send_timeout 60;
        proxy_read_timeout 60;
        proxy_pass http://192.168.3.46/html/favicon.ico;
    }

location /simple_load.swf {
        proxy_buffering off;
        proxy_ignore_client_abort off;
        proxy_intercept_errors on;
        proxy_next_upstream error timeout invalid_header;
        proxy_redirect off;
        proxy_set_header X-Host $http_host;

```

# proxy\_set\_header X-Forwarded-For $remote\_addr;

```
        proxy_connect_timeout 60;
        proxy_send_timeout 60;
        proxy_read_timeout 60;
        proxy_pass http://192.168.3.46/simple_load.swf;
    }

    # redirect server error pages to the static page /50x.html
    #
    error_page 500 502 503 504 /50x.html;
    location = /50x.html {
        root html;
    }

}

```

}

Posted at Nginx Forum:

> **[Question: http video streaming and nginx ram usage](https://forum.nginx.org/read.php?2,180840,180840#msg-180840)**
>
> Hi everyone, I'm using Nginx to forward incoming http requests (from the Internet) to an Aviosys 9100A+ (low-cost) IP video server. My Nginx 0.7.64 runs on a small embedded linux device under OpenWRT - the device has only 13 MB of free ram when nginx...

---

<div class="post-metadata">

**Author:** ![birdy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/85e7bf/32.png) [@birdy](https://www.ruby-forum.com/u/birdy)\
**Post date:** [March 8, 2011, 11:35pm UTC](https://www.ruby-forum.com/t/question-http-video-streaming-and-nginx-ram-usage/204224/2 "2011-03-08T23:35:54Z")

</div>

On Tue, Mar 08, 2011 at 12:15:23AM -0500, birdy wrote:

Hi there,

The short answer is: I don’t know the answer to your question.

But read on anyway…

> the stream cannot change the video server’s settings via the web  
> interface, because my nginx config does not forward the “banned” URLs.

Note that location{}s do not match ?query\_strings. So some of your  
location blocks are not used at all. If you enable the debug log, you’ll  
see exactly which location is used for each request.

You may be allowing through more URLs than you  
think. /Simple/home.htm?DO\_EVIL, for example, will be proxied.

> This video server transfers the images to the viewing person’s web  
> browser in one long http response in real-time.
> 
> As I wrote, In my setup, I reverse-proxy only the allowed URLs (i.e. the  
> ones to “get the video”) on to the video server with nginx. This works  
> fine, but nginx seems to buffer the http data that it forwards locally.

According to the notes at  
[GitHub - nginxinc/nginx-wiki: ARCHIVED -- Source for the now archived NGINX Wiki section of https://www.nginx.com · GitHub](http://wiki.nginx.org/HttpProxyModule#proxy_buffering) that shouldn’t  
happen. So if it does, it’s a bug. (Or a documentation/version error.)

Can you get logs, from nginx or the system, showing the memory use? That  
might allow you…

> So while viewing the video stream, nginx consumes more and more RAM  
> until the little linux device crashes.

…to kill and restart nginx before the system falls over. (Or, if it  
shows something other than nginx eating the ram, then you’ll know what  
else to fix.)

> However, if I stop viewing the stream after 1 or 2 minutes, before RAM  
> runs out, the memory gets freed again.  
> I believe it frees the ram because the request is finished.

> Has anyone got a hint for me what I could do to stop nginx from keeping  
> the long request in RAM (this is what I think what happens, at least)?
> 
> Any help would be greatly appreciated!

As you already have,

proxy\_buffering off;

should be enough. So there’s something else going on.

I’d suggest to try simplifying the nginx config: get rid of

location /GetStatus.cgi?JsVar=sStatus  
location /Simple/home.htm?IMG  
location /Simple/home.htm?ATV

since they are (almost certainly) never matched (unless you actually  
make a request like “/Simple/home.htm%3fATV”).

Then take all of the repeated identical proxy\_\* directives and put them  
in the server block, outside all location{}s. And then remove them from  
the individual location{} blocks, leaving just proxy\_pass there.

That should shrink the file size quite a bit, which might make it easier  
for someone else to analyse the problem.

Good luck with it,

## f

Francis D. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)

---

<div class="post-metadata">

**Author:** ![birdy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/85e7bf/32.png) [@birdy](https://www.ruby-forum.com/u/birdy)\
**Post date:** [March 9, 2011, 12:57pm UTC](https://www.ruby-forum.com/t/question-http-video-streaming-and-nginx-ram-usage/204224/3 "2011-03-09T12:57:28Z")

</div>

Hello!

On Tue, Mar 08, 2011 at 12:15:23AM -0500, birdy wrote:

> I’m using Nginx to forward incoming http requests (from the Internet) to  
> an Aviosys 9100A+ (low-cost) IP video server.

[…]

> As I wrote, In my setup, I reverse-proxy only the allowed URLs (i.e. the  
> ones to “get the video”) on to the video server with nginx. This works  
> fine, but nginx seems to buffer the http data that it forwards locally.  
> So while viewing the video stream, nginx consumes more and more RAM  
> until the little linux device crashes.
> 
> However, if I stop viewing the stream after 1 or 2 minutes, before RAM  
> runs out, the memory gets freed again.  
> I believe it frees the ram because the request is finished.

nginx frees (most of) memory allocated for request only when  
request is finished, this is how it’s expected to work.

Known issue with long-running requests is that chunked filter will  
allocate some small amount of memory for each chunk send, and this  
may grow big enough for long-running requests with “proxy\_buffering”  
set to “off”.

Workaround is

```
chunked_transfer_encoding off;

```

as available in nginx 0.8.35+.

Maxim D.

p.s. As already pointed out, your config isn’t correct. Location  
directive can’t be used to test query string arguments. This is  
irrelevant though.

---

<div class="post-metadata">

**Author:** ![birdy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/85e7bf/32.png) [@birdy](https://www.ruby-forum.com/u/birdy)\
**Post date:** [March 10, 2011, 6:04pm UTC](https://www.ruby-forum.com/t/question-http-video-streaming-and-nginx-ram-usage/204224/4 "2011-03-10T18:04:54Z")

</div>

Hi Francis, Hi Maxim,

thank you very much for your advice!

I will clean up my config…

The real work to do for me is to adapt and compile Nginx 0.8.35 or newer  
for the OpenWRT distro I’m using.

This is because the latest nginx version available pre-built (as a  
package) for the “atheros” platform of my router is 0.7.64, and I could  
not find a distro that has a newer version.

Philipp

Posted at Nginx Forum:

> **[Re: Question: http video streaming and nginx ram usage](https://forum.nginx.org/read.php?2,180840,182022#msg-182022)**
>
> Hi everyone, I'm using Nginx to forward incoming http requests (from the Internet) to an Aviosys 9100A+ (low-cost) IP video server. My Nginx 0.7.64 runs on a small embedded linux device under OpenWRT - the device has only 13 MB of free ram when nginx...