behavior of cache manager in version 1.10.3

[Maxim Dounin]

Hello!

On Mon, May 15, 2017 at 08:02:18AM -0400, Michael Corn wrote:

> The documentation for proxy_cache_path states:
>            The data is removed in iterations configured by manager_files,
> manager_threshold, and manager_sleep parameters (1.11.5).
> 
> I was wondering what the behavior of the cache manager was prior to release
> 1.11.5  (specifically, in version 1.10.3).

Prior to changes in 1.11.5, cache manager removed all files it has 
to remove according to "inactive" and "max_size" configured.  In 
some cases this caused responsiveness problems due to huge disk 
activity though (for example, if max_size was changed to a smaller 
value), and hence the change.  Now cache manager sometimes sleeps 
even if there are cache items to remove, to avoid overloading of 
the IO subsystem.

> How often does the cache manager wake up to clean?

If cache manger has nothing to do, it sleeps till next expected 
expiration of a cache item as per "inactive", or for 10 seconds, 
whichever is sooner.  That is, if there are no inactive cache 
items, "max_size" will be checked once in 10 seconds.

-- 
Maxim Dounin
http://nginx.org/