On 1/18/11 at 7:20 PM, [email protected] (kowsik) wrote:
A couple of questions: 1. Is anyone using erlang views (as opposed to Javascript) in a production environment? 2. For the map and filter functions, is there any kind of published performance numbers that show the speed up? Yes, I'm aware of the built-in reduce functions and I'm using them extensively. I'm more interested in erlang filters + map functions for a write-heavy app that I'm working on. Thanks, K --- http://www.pcapr.net http://twitter.com/pcapr http://labs.mudynamics.com
We moved over to erlang views and filters a few months ago in a multi-master replicated system. The performance gains were quite good and overall CPU load was lower, though I don't have numbers available at hand.
For what it's worth: another motivation for the switchover were problems with the management of the couchjs processes that are spawned by couch to invoke the spider monkey javascript engine.
Under some loads and data access patterns using filtered change listeners, we could repeatably drive couch to "meltdown" as processes piled up when change listeners were opened/failed/re-opened due to couch failing to send heart beats for extended periods.
Moving to erlang at least eliminated the couchjs processes and sped up the filtering, though the problem with heart beats ultimately required some changes both to the filter's logic, which prevented a producer from reading its own writes, and in the front-end application framework to work around the problem.
Matt
