# Bug while using "proxy\_cache\_use\_stale updating"

**URL:** <https://www.ruby-forum.com/t/bug-while-using-proxy-cache-use-stale-updating/174480>\
**Category:** NGINX\
**Created:** [August 27, 2009, 11:15am UTC](https://www.ruby-forum.com/t/bug-while-using-proxy-cache-use-stale-updating/174480 "2009-08-27T11:15:22Z")\
**Posts on this page:** 10\
**Page:** 1

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**Author:** ![JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ee59a6/32.png) [@JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/u/JSSSSrSSSSme_Loyet)\
**Post date:** [August 27, 2009, 11:15am UTC](https://www.ruby-forum.com/t/bug-while-using-proxy-cache-use-stale-updating/174480/1 "2009-08-27T11:15:22Z")

</div>

Hi everybody,

I come up with a strange bug. I’m using nginx as a proxy cache to  
apache.

I’m using the following conf (only useful line):  
proxy\_buffering on;  
proxy\_buffers 4 8k;  
proxy\_cache\_use\_stale updating error timeout invalid\_header http\_500  
http\_502 http\_503 http\_504;  
proxy\_cache\_key $scheme$host$request\_uri;  
proxy\_send\_timeout 5;  
proxy\_read\_timeout 120;  
proxy\_connect\_timeout 5;  
proxy\_hide\_header X-Powered-By;  
proxy\_cache\_path /LIBRE/nginx/cache levels=1:2  
keys\_zone=cache.www:10m inactive=1d max\_size=4g;  
proxy\_ignore\_headers Expires Cache-Control;

…

upstream backend.www {  
server 10.26.49.71:8004;  
server 10.26.49.71:8005;  
server 10.26.49.71:8006;  
server 10.26.49.71:8007;  
server 10.26.49.71:8011;  
server 10.26.49.71:8012;  
server 10.26.49.71:8015;  
server 10.26.49.71:8016;  
}

server {  
proxy\_cache cache.www;  
location / {  
proxy\_cache\_valid 200 302 1m;  
gzip on;  
proxy\_pass [http://backend.www](http://backend.www);  
}  
…  
Until now everything was working great. But a bug come up to me.

It seems that for an unknown reason, an “update cache” request didn’t  
go well. And it stays as is (state: UPDATING). So every next request  
are served from cache because for nginx there is still a request to  
the backend running for this request. So even hours after having  
removing a page in the backend, nginx is still serving the old and  
valid (not 404) content.

Here is what I have in the access log.

17:19:26 /pid21838/test.html 200 MISS  
17:20:32 /pid21838/test.html 200 EXPIRED ← more than one minute  
later, the backend is requested to update the cache  
17:20:49 /pid21838/test.html 200 HIT ← less than one minute later,  
the cache is served  
17:20:49 /pid21838/test.html 200 HIT ← the same  
17:21:40 /pid21838/test.html 404 EXPIRED ← The cache is expired,  
request backend. The backend answers with a 404. But the cache does  
not seem to be updated  
17:21:42 /pid21838/test.html 200 UPDATING ← all the next requests  
are served from stale cache.  
17:22:09 /pid21838/test.html 200 UPDATING  
17:23:06 /pid21838/test.html 200 UPDATING  
17:27:00 /pid21838/test.html 200 UPDATING  
17:32:16 /pid21838/test.html 200 UPDATING  
17:41:20 /pid21838/test.html 200 UPDATING  
17:44:06 /pid21838/test.html 200 UPDATING  
17:45:09 /pid21838/test.html 200 UPDATING  
17:47:01 /pid21838/test.html 200 UPDATING  
17:52:06 /pid21838/test.html 200 UPDATING  
17:52:08 /pid21838/test.html 200 UPDATING  
19:12:08 /pid21838/test.html 200 UPDATING  
19:20:59 /pid21838/test.html 200 UPDATING  
19:34:36 /pid21838/test.html 200 UPDATING  
19:58:00 /pid21838/test.html 200 UPDATING  
20:11:55 /pid21838/test.html 200 UPDATING ← 3 hours later: still the  
same

I can reproduce the problem:

1- create a page on the backend (say /test.html)  
2- request the frontend for /test.html → MISS 200  
3- request the frontend for /test.html before it expires → HIT 200  
4- request the frontend for /test.html after it expires → EXPIRED 200  
5- remove /test.html from the backend  
6- request the frontend for /test.html after it expires → EXPIRED 404  
6- request the frontend for /test.html any time you want → UPDATING  
200 (the old /test.html is still served)

I’m using nginx 0.8.4.

I didn’t have time to test with newer releases.

Hope it helps

++ Jerome

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<div class="post-metadata">

**Author:** ![JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ee59a6/32.png) [@JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/u/JSSSSrSSSSme_Loyet)\
**Post date:** [August 28, 2009, 12:06pm UTC](https://www.ruby-forum.com/t/bug-while-using-proxy-cache-use-stale-updating/174480/2 "2009-08-28T12:06:21Z")

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Hi Jerome, I may be hitting a similar issue with 0.8.10. Backend is also  
an apache box. I don’t see the MISS / HIT / UPDATING / EXPIRED status  
strings in my log. What log\_format are you using to log your accesses?  
The default?

Posted at Nginx Forum:

> **[Re: Bug while using "proxy\_cache\_use\_stale updating"](https://forum.nginx.org/read.php?2,5225,5243#msg-5243)**
>
> Hi everybody, I come up with a strange bug. I'm using nginx as a proxy cache to apache. I'm using the following conf (only useful line): proxy\_buffering on; proxy\_buffers 4 8k; proxy\_cache\_use\_stale updating error timeout invalid\_header http\_5

---

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**Author:** ![JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ee59a6/32.png) [@JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/u/JSSSSrSSSSme_Loyet)\
**Post date:** [August 28, 2009, 2:13pm UTC](https://www.ruby-forum.com/t/bug-while-using-proxy-cache-use-stale-updating/174480/3 "2009-08-28T14:13:22Z")

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2009/8/27 icqheretic [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

> Hi Jerome, I may be hitting a similar issue with 0.8.10.

I confirm that the bug is having a similar issue with 0.8.10. I’ve  
just tested it.

By the way, the bug does not appear if I add 404 page to  
proxy\_cache\_valid directive:

proxy\_cache\_valid 200 302 404 30s;

An other solution is to remove the “updating” option for the  
“proxy\_cache\_use\_stale” directive.

I’m looking into the code to try to find a solution.

++ jerome

---

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**Author:** ![JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ee59a6/32.png) [@JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/u/JSSSSrSSSSme_Loyet)\
**Post date:** [August 28, 2009, 5:41pm UTC](https://www.ruby-forum.com/t/bug-while-using-proxy-cache-use-stale-updating/174480/4 "2009-08-28T17:41:49Z")

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2009/8/27 icqheretic [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

> Hi Jerome, I may be hitting a similar issue with 0.8.10. Backend is also an apache box. I don’t see the MISS / HIT / UPDATING / EXPIRED status strings in my log. What log\_format are you using to log your accesses? The default?

I’m not using default log\_format. You can add the  
$upstream\_cache\_status variable, it should log the info you want.

++ Jerome

---

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**Author:** ![JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ee59a6/32.png) [@JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/u/JSSSSrSSSSme_Loyet)\
**Post date:** [August 28, 2009, 6:52pm UTC](https://www.ruby-forum.com/t/bug-while-using-proxy-cache-use-stale-updating/174480/5 "2009-08-28T18:52:39Z")

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On Fri, Aug 28, 2009 at 03:57:04PM +0200, J?r?me Loyet wrote:

> > šproxy\_cache\_valid 200 302 404 30s;  
> > +++ src/http/ngx\_http\_upstream.c 2009-08-28 15:54:43.000000000 +0200  
> > @@ -2574,6 +2574,8 @@  
> > } else if (p-\>upstream\_error) {  
> > ngx\_http\_file\_cache\_free(r, u-\>pipe-\>temp\_file);  
> > }
> 
> - 
> 
> ```
> } else {
> 
> ```
> 
> - 
> 
> ```
> ngx_http_file_cache_free(r, u->pipe->temp_file);
> }
> 
> ```
> 
> #endif

No, this is not correct fix. I will look this.

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**Author:** ![JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ee59a6/32.png) [@JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/u/JSSSSrSSSSme_Loyet)\
**Post date:** [August 28, 2009, 4:03pm UTC](https://www.ruby-forum.com/t/bug-while-using-proxy-cache-use-stale-updating/174480/6 "2009-08-28T16:03:26Z")

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Le 28 août 2009 13:59, Jérôme Loyet[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) a écrit :

> An other solution is to remove the “updating” option for the  
> “proxy\_cache\_use\_stale” directive.
> 
> I’m looking into the code to try to find a solution.

After several trials, I made a patch. This seems to correct the issue.  
Hope no other bugs are implied buy this diff:

— src/http/ngx\_http\_upstream.c.orig 2009-08-23 18:10:39.000000000  
+0200  
+++ src/http/ngx\_http\_upstream.c 2009-08-28 15:54:43.000000000  
+0200  
@@ -2574,6 +2574,8 @@  
} else if (p-\>upstream\_error) {  
ngx\_http\_file\_cache\_free(r, u-\>pipe-\>temp\_file);  
}

- 

```
   } else {

```

- 

```
       ngx_http_file_cache_free(r, u->pipe->temp_file);
   }

```

#endif

---

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**Author:** ![JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ee59a6/32.png) [@JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/u/JSSSSrSSSSme_Loyet)\
**Post date:** [September 1, 2009, 3:29pm UTC](https://www.ruby-forum.com/t/bug-while-using-proxy-cache-use-stale-updating/174480/7 "2009-09-01T15:29:57Z")

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On Thu, Aug 27, 2009 at 11:06:46AM +0200, J?r?me Loyet wrote:

> proxy\_send\_timeout 5;  
> server 10.26.49.71:8004;  
> proxy\_cache cache.www;  
> are served from cache because for nginx there is still a request to  
> the cache is served  
> 17:41:20 /pid21838/test.html 200 UPDATING
> 
> 200 (the old /test.html is still served)
> 
> I’m using nginx 0.8.4.
> 
> I didn’t have time to test with newer releases.
> 
> Hope it helps

The patch.

---

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**Author:** ![JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ee59a6/32.png) [@JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/u/JSSSSrSSSSme_Loyet)\
**Post date:** [September 1, 2009, 4:05pm UTC](https://www.ruby-forum.com/t/bug-while-using-proxy-cache-use-stale-updating/174480/8 "2009-09-01T16:05:06Z")

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Thx igor, I’ll test that asap

2009/9/1 Igor S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid):

---

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**Author:** ![JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ee59a6/32.png) [@JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/u/JSSSSrSSSSme_Loyet)\
**Post date:** [December 19, 2009, 3:25pm UTC](https://www.ruby-forum.com/t/bug-while-using-proxy-cache-use-stale-updating/174480/9 "2009-12-19T15:25:40Z")

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I was wondering if anyone else is still having this problem of Nginx  
getting stuck in the UPDATING state after upgrading to the fixed version  
of Nginx.

I saw this using Nginx 0.7.62 and I upgraded to 0.8.24 because I saw it  
had been fixed, but recently saw the problem again.

Here is my configuration:

```
proxy_cache_path /mnt/nginx_cache levels=1:2
                 keys_zone=one:10m
                 inactive=7d max_size=10g;
proxy_cache_path /mnt/nginx_cache_media levels=1:2
                 keys_zone=MEDIA:10m
                 inactive=7d max_size=5g;
proxy_temp_path /var/www/nginx_temp;

server {
    listen 80;
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_pass_header Set-Cookie;
    client_max_body_size 8m;

    # capture cookies for use in the cache key
    set $wordpress_logged_in "";
    set $comment_author_email "";
    set $comment_author "";
    if ($http_cookie ~* "wordpress_logged_in_[^=]*=([^%]+)%7C") {
        set $wordpress_logged_in wordpress_logged_in_$1;
    }
    if ($http_cookie ~* "comment_author_email_[^=]*=([^;]+)(;|$)") {
        set $comment_author_email comment_author_email_$1;
    }
    if ($http_cookie ~* "comment_author_[^=]*=([^;]+)(;|$)") {
        set $comment_author comment_author_$1;
    }
    set $my_cache_key 

```

$scheme$host$uri$is\_args$args$wordpress\_logged\_in$comment\_author\_email$comment\_author;

```
    # proxy cache config for media files
    location ~* \.(gif|jpg|jpeg|png|js|css)$ {
        proxy_pass http://backend;
        proxy_cache MEDIA;
        proxy_cache_key $my_cache_key;

        proxy_cache_valid 200 302 304 30d;
        proxy_cache_valid 301 1h;
        proxy_cache_valid any 1m;
        proxy_cache_use_stale error timeout invalid_header updating 

```

http\_500 http\_502 http\_503 http\_504 http\_404;  
expires 30d;  
}

```
    # proxy cache config for all other files
    location / {
        proxy_pass http://backend;
        proxy_cache one;
        proxy_cache_key $my_cache_key;

        proxy_cache_valid 200 302 304 10m;
        proxy_cache_valid 301 1h;
        proxy_cache_valid any 1m;
        proxy_cache_use_stale error timeout invalid_header updating 

```

http\_500 http\_502 http\_503 http\_504 http\_404;  
}

```
    # Don't use the cache for the following locations
    location /wp-admin {
        proxy_read_timeout 180;
        proxy_pass http://backend;
    }
    location /wp-login.php { proxy_pass http://backend; }
}

```

Posted at Nginx Forum:

> **[Re: Bug while using "proxy\_cache\_use\_stale updating"](https://forum.nginx.org/read.php?2,5225,30772#msg-30772)**
>
> Hi everybody, I come up with a strange bug. I'm using nginx as a proxy cache to apache. I'm using the following conf (only useful line): proxy\_buffering on; proxy\_buffers 4 8k; proxy\_cache\_use\_stale updating error timeout invalid\_header http\_5

---

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**Author:** ![JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/ee59a6/32.png) [@JSSSSrSSSSme\_Loyet](https://www.ruby-forum.com/u/JSSSSrSSSSme_Loyet)\
**Post date:** [November 15, 2011, 4:36am UTC](https://www.ruby-forum.com/t/bug-while-using-proxy-cache-use-stale-updating/174480/10 "2011-11-15T04:36:55Z")

</div>

I have 0.8.54, and I just hit this issue, which resulted in the RSS feed  
not updating for a full day. Due to the way my server is configured,  
because of my cookies, I was getting straight to the feed bypassing the  
cache and only found the problem when using incognito mode without  
cookies. A server restart seemed to fix the problem for now.

Igor, is this fixed in some version \>0.8.54?

Thanks,  
Artem

Posted at Nginx Forum:

> **[Re: Bug while using "proxy\_cache\_use\_stale updating"](https://forum.nginx.org/read.php?2,5225,218347#msg-218347)**
>
> Hi everybody, I come up with a strange bug. I'm using nginx as a proxy cache to apache. I'm using the following conf (only useful line): proxy\_buffering on; proxy\_buffers 4 8k; proxy\_cache\_use\_stale updating error timeout invalid\_header http\_5