mongodb map reduce on multicore server

Question

I have a mongodb with thousands of records holding very long vectors. I am looking for correlations between an input vector with my MDB data set using a certain algorithm.<

Answer 1

Map reduce in MongoDB uses Spidermonkey, a single-threaded Javascript engine, so it is not possible to configure multiple processes (and there are no "tricks"). There is a JIRA ticket to use a multi-threaded JS engine, which you can follow here: https://jira.mongodb.org/browse/SERVER-2407

If possible, I would consider looking into the new aggregation framework (available in MongoDB version 2.2), which is written in C++ instead of Javascript and may offer performance improvements: http://docs.mongodb.org/manual/applications/aggregation/