File is not refreshed when using proxy_cache_use_stale

Server NGINX
1

I have following config:

location /images {
proxy_pass http://my.host;
proxy_redirect off;
proxy_cache static-cache;
proxy_cache_valid any 5m;
proxy_cache_valid 404 5m;
proxy_cache_use_stale updating invalid_header error timeout http_502;
}

The idea is that if backend server reply with error/timeout/invalid
header it will return stale version and cache it for 5m. Generally it
works ok but sometimes I have situation when one of my proxy cache
servers (I have 3 of them) returns stale version and will not refresh
file until I delete nginx cache files. Here is output from nginx -V:

$ nginx -V
nginx version: nginx/0.7.65
TLS SNI support enabled
configure arguments: --conf-path=/etc/nginx/nginx.conf
–error-log-path=/var/log/nginx/error.log --pid-path=/var/run/nginx.pid
–lock-path=/var/lock/nginx.lock
–http-log-path=/var/log/nginx/access.log
–http-client-body-temp-path=/var/lib/nginx/body
–http-proxy-temp-path=/var/lib/nginx/proxy
–http-fastcgi-temp-path=/var/lib/nginx/fastcgi --with-debug
–with-http_stub_status_module --with-http_flv_module
–with-http_ssl_module --with-http_dav_module
–with-http_gzip_static_module --with-http_realip_module --with-mail
–with-mail_ssl_module --with-ipv6
–add-module=/build/buildd/nginx-0.7.65/modules/nginx-upstream-fair

Is it known problem or I am doing something wrong?

Posted at Nginx Forum:

2

Hello!

On Fri, Feb 10, 2012 at 05:05:45AM -0500, radarek wrote:

–error-log-path=/var/log/nginx/error.log --pid-path=/var/run/nginx.pid

Is it known problem or I am doing something wrong?

The above may happen if nginx worker process dies, leaving cache
node marked as being updated. Try looking into your logs to see
if this is the case. That is: if you have alerts about “worker
process exited on signal …” - you have a problem, and this is
expected result.

In any case it’s good idea to upgrade from long unsupported 0.7.x
branch to at least stable 1.0.x.

Maxim D.

3

Maxim D. Wrote:

expected result.
I looked in the error log and found exactly what you suggested:
2011/08/09 08:50:15 [alert] 25485#0: cache loader process 25488 exited
on signal 9
2011/10/16 17:16:36 [alert] 25509#0: worker process 25510 exited on
signal 6
2012/01/16 12:48:13 [alert] 9183#0: worker process 9184 exited on signal
6
2012/01/16 14:19:24 [alert] 9183#0: worker process 11897 exited on
signal 6

Shouldn’t it be treated as a bug? Do you know what thing could caused
sending signal 6 to worker process?

In any case it’s good idea to upgrade from long
unsupported 0.7.x
branch to at least stable 1.0.x.

Yeah, I will probably do it in near future.

Posted at Nginx Forum:

4

Hello!

On Fri, Feb 10, 2012 at 09:45:40AM -0500, radarek wrote:

process exited on signal …" - you have a
2012/01/16 14:19:24 [alert] 9183#0: worker process 11897 exited on
signal 6

Shouldn’t it be treated as a bug? Do you know what thing could caused
sending signal 6 to worker process?

There are lots of bugs fixed since 0.7.65 which may cause this.
Signal 6 is likely generated by libc due to detected memory
corruption.

In any case it’s good idea to upgrade from long
unsupported 0.7.x
branch to at least stable 1.0.x.

Yeah, I will probably do it in near future.

Yes, please.

Maxim D.