[crit] 16665#0 unlink()

[Jim Ohlstein]

On 05/03/13 18:01, Maxim Dounin wrote:
> Hello!
>

>
> You've configured two distinct caches to use single directory.
> This is not how it's expected to work.
>
> You should use distinct directories for each cache you configure.
> If you want different locations to use the same cache - just use
> the same cache in the proxy_cache directive.
>
> [...]
>
>> Is this bad practice to share caches among subdomains? Is sharing the cache
>> the reason why I'm getting unlink() errors?
>
> It's ok to use the same cache for different locations/servers.
> But it's really bad idea to configure multiple caches in the same
> directory, and this is what causes your problems.
>

Maxim,

I have just seen a similar situation using fastcgi cache. In my case I 
am using the same cache (but only one cache) for several server/location 
blocks. The system is a fairly basic nginx set up with four upstream 
fastcgi servers and ip hash. The returned content is cached locally by 
nginx. The cache is rather large but I wouldn't think this would be the 
cause.

Relevant config:

http {

     ....

     upstream fastcgi_backend {
         ip_hash;
         server  10.0.2.1:xxxx;
         server  10.0.2.2:xxxx;
         server  10.0.2.3:xxxx;
         server  10.0.2.4:xxxx;
         keepalive   8;
     }

     fastcgi_cache_path /var/nginx/fcgi_cache levels=1:2 
keys_zone=one:512m max_size=250g inactive=24h;

     ....
}

server1 {
     ....

     server_name domain1.com;

     ....

     location ~ \.blah$ {
         fastcgi_pass fastcgi_backend;
         include /usr/local/etc/nginx/fastcgi_params;
         fastcgi_buffers 64 4k;
         fastcgi_read_timeout    120s;
         fastcgi_keep_conn   on;
         fastcgi_send_timeout    120s;
         fastcgi_cache   one;
         fastcgi_cache_key $scheme$request_method$host$request_uri;
         fastcgi_cache_lock on;
         fastcgi_cache_lock_timeout 5s;
         fastcgi_cache_methods GET HEAD;
         fastcgi_cache_min_uses 1;
         fastcgi_cache_use_stale error updating;
         fastcgi_cache_valid 200 302 60m;
         fastcgi_cache_valid 301 12h;
         fastcgi_cache_valid 404 5m;
     }

  ....

}

The other sever/location blocks are pretty much identical insofar as 
fastcgi and cache are concerned.

When I upgraded nginx using the "on the fly" binary upgrade method, I 
saw almost 400,000 lines in the error log that looked like this:

2013/05/04 17:54:25 [crit] 65304#0: unlink() 
"/var/nginx/fcgi_cache/7/2e/899bc269a74afe6e0ad574eacde4e2e7" failed (2: 
No such file or directory)
2013/05/04 17:54:25 [crit] 65304#0: unlink() 
"/var/nginx/fcgi_cache/7/2e/42adc8a0136048b940c6fcaa76abf2e7" failed (2: 
No such file or directory)
2013/05/04 17:54:25 [crit] 65304#0: unlink() 
"/var/nginx/fcgi_cache/7/2e/c3656dff5aa91af1a44bd0157045d2e7" failed (2: 
No such file or directory)
2013/05/04 17:54:25 [crit] 65304#0: unlink() 
"/var/nginx/fcgi_cache/7/2e/de75207502d7892cf377a3113ea552e7" failed (2: 
No such file or directory)
2013/05/04 17:54:25 [crit] 65304#0: unlink() 
"/var/nginx/fcgi_cache/7/2e/c2205e6a3df4f29eb2a568e435b2b2e7" failed (2: 
No such file or directory)
2013/05/04 17:54:25 [crit] 65304#0: unlink() 
"/var/nginx/fcgi_cache/7/2e/6ccaa4244645e508dad3d14ff73ea2e7" failed (2: 
No such file or directory)
2013/05/04 17:54:25 [crit] 65304#0: unlink() 
"/var/nginx/fcgi_cache/7/2e/76b4b811553756a2989ae40da863d2e7" failed (2: 
No such file or directory)
2013/05/04 17:54:25 [crit] 65304#0: unlink() 
"/var/nginx/fcgi_cache/7/2e/53d40a6399ba6dcf08bc0a52623932e7" failed (2: 
No such file or directory)
2013/05/04 17:54:25 [crit] 65304#0: unlink() 
"/var/nginx/fcgi_cache/7/2e/68ff8b00492991a2e3ba5ad7420d42e7" failed (2: 
No such file or directory)
2013/05/04 17:54:25 [crit] 65304#0: unlink() 
"/var/nginx/fcgi_cache/7/2e/19c079c9a1e0bcacb697af123d47f2e7" failed (2: 
No such file or directory)

The backend logs show nothing of note.

-- 
Jim Ohlstein