[development] Counterintuitive but true: Caching makes a high-traffic site slower

Dries Buytaert dries at buytaert.net
Fri Dec 30 21:46:01 UTC 2005

On 29 Dec 2005, at 18:24, John Handelaar wrote:
> Try turning it off if your slow query log starts showing
> cache-related things taking 90 seconds (!) or more (!!).

That's somewhat odd; 90 seconds looks extreme.  Table locks are fast  
but have poor concurrency.  However, UPDATE and INSERT queries should  
get a higher priority than SELECT queries to prevent starvation.   
They should only wait for the active SELECT queries on the table to  
complete.  The UPDATE/INSERT sequence in cache_set() should be fast  
so '90 seconds or more' is somewhat ... long.  To me, it suggests  
that some queries are really slow, regardless any table locking.  Can  
you share what queries take that long?

Whether we can support InnoDB out of the box depends on its  
availability/adoption.  Do we have any references about that?  Any  
other systems that ship with InnoDB?

> PS:  Still no bigsite/performance forum.  Have we decided
> that Drupal doesn't *need* to scale?  I missed that meeting.

That's somewhat harsh.  Isn't making Drupal scale developer-specific  
and suitable for development at drupal.org?

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

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