[drupal-devel] caching issues

[Dries Buytaert]

Jeremy Andrews wrote:
>>- The cache has a much higher miss rate than expected on drupal.org at 
>>least because the site is constantly being crawled by spiders. Pages 
>>that are visited often get re-cached quickly after a wipe, but this 
>>doesn't happen for the random access pattern that is common for spiders 
>>and also for posts reached through searching.
> 
> Yes, this is true.  And I remember the data you and Dries came up with. 
> However I still get a large boost from the cache.  I believe this is
> because much of the anonymous traffic is due to links from other news
> sites, and thus the same page is loaded many times in rapid succession. 
> Thus, only a percentage of page loads benefit from the cache, but it's a
> significant enough percentage to have a noticeable affect on performance. 
> Disabling the cache (or flushing it every second) has a negative affect on
> performance.

Caching helps a lot.  That said, developers should _not_ rely on pages 
being cached.  The cache is no substitute for badly performing code 
because 50% of the time, the badly performing code is executed.

>>- Any aggressive caching should be implemented as an optional feature as
>>it is useless for small sites. Perhaps we could change the cache option 
>>into three states: "No caching" "Mild caching" "Aggressive caching".
> 
> Yes, I agree.  But is there interest in merging an agressive type caching
> mechanism?

Yes, there is.

-- 
Dries Buytaert  ::  http://www.buytaert.net/