[drupal-devel] Drupal.org cache statistics

Moshe Weitzman weitzman at tejasa.com
Thu May 26 19:47:50 UTC 2005

Thanks Dries.

Wow. This is disappointing and a bit confusing. How can we interpret the 
seemingly contradictory changes described in 2 vs. 3?

I have to believe we can get more than 30% cache hits when our user base 
is 85% anonymous. Part of me wonders if we are not getting skewed 
results because of web crawlers. Thos crawlers spider all of our obscure 
pages and thus cause cache misses.

I agree that we need to work on the non cached case.


Dries Buytaert wrote:
> 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.
> Results:
> 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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