blank page on some micro-cached pages

[Maxim Dounin]

Hello!

On Sat, Nov 23, 2013 at 11:00:52AM +0100, Ronald Van Assche wrote:

> Running Nginx 1.5.7 on Freebsd 9.1
> with php-pfm 5.5.3
> 
> a wordpress site is "micro-cached" , but for some strange reason 
> and not always , some pages ( wordpress post or pages even 3 or 
> 7 days after their publication)  are rendered for some users ( 
> me and others and not always the same, with different browsers) 
> as blank pages and the same connexion can read other cached 
> pages/post with no problems.  
> 
> The size of the global site in /cache is 72 Kb. Very small 
> indeed.
> 
> The bad cached pages are logged like this :
> "GET /url  HTTP/1.1" 200 31
> 
> always 200 as a result code, and 31 for its size.. 31 is not the 
> actual size of the page of course.
> 
> If a refresh my local cache ( SHIFT CMD-R) on chrome , the 
> correct page is reloaded and cached in /cache/x/y/somefile by 
> nginx.
> 
> Any help ?

Size is suspiciously small, and I would suggest it's some error 
returned by php.

You may try adding $upstream_cache_status to access log to get 
some more details (likely there will be MISS or similar state 
there, indicating the response was returned by a php).  If it 
doesn't help, some more hints about debugging can be found here:

http://wiki.nginx.org/Debugging

-- 
Maxim Dounin
http://nginx.org/en/donation.html