[drupal-devel] Drupal.org cache statistics

Dries Buytaert dries at buytaert.net
Thu May 26 18:14:55 UTC 2005

Hello world,

november last year, I profiled drupal.org's cache observations.   
Yesterday, Moshe asked to profile it again so we could evaluate the  
usefulness of Jeremy's "loose caching" mechanism.

The past 20 hours, I logged 93.000 unique page requests using the  
patch at http://buytaert.net/temporary/cache-statistics.patch.  Loose  
caching was enabled.


1. Last year we found that authenticated users were responsible for  
15,8 % of all page views.  A year later, we see that authenticated  
users are responsible for 14,9% of all page views.

2. Last year we found that only 27.9% of the page requests actually  
benefited from the cache system.  That is, for more than 2/3th of the  
page requests, we had to generate a page dynamically.  A year later,  
using "loose caching" rather than "strict caching", we see that 30,7%  
of the page requests benefit from the cache system.  Read: we still  
have a lot of page cache misses! :(

3. Last year, we found that the cache got flushed once every 207 page  
requests.  A year later, we observe that the cache got flushed once  
every 190 page requests.

We conclude that:

1. Loose caching does not significantly -- or not necessarily --  
improve the behavior of drupal.org's page cache (though I'd like to  
believe that it does when there are sudden traffic spikes/bursts).

2. When writing code, we can NOT assume that a page will benefit from  
being cached.

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

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