multi-core views (was Re: Silent corruption of large numbers)

[Adam Kocoloski <ko...@apache.org>]

On Nov 9, 2009, at 3:20 PM, Roger Binns wrote:

> The biggest performance benefit for me would be if as many copies of  
> the
> Javascript external process were run as I have processor cores.  It  
> is quite
> frustrating watching one core be 100% busy and the other 0% busy  
> while a
> view is being built.

Hi Roger, You should see trunk make use of 2 cores now when building a  
single view from a single DB.  The more views you build, the more  
cores Couch will use.  The trouble with spawning more JS processes for  
the same design doc is that the Erlang VM is usually the limiting  
factor now, and moreover its basically a single process inside the  
Erlang VM.  So until we optimize the Erlang side or do some other  
trick (say, use BERT instead of JSON to communicate with the view  
server if the its supported), spawning off more JS processes will  
offer diminishing returns.  Best,

Adam