node.js - Tuning node-mongodb-native connection pool size -

i've got express app talking mongodb via node-mongodb-native driver. requests in app intermittently slow. tools or strategies confirm or rule out driver connection pool size bottleneck?

here's some discussion of tuning pool size, it's pretty inconclusive. aheckmann notes default of 5 plenty, while tinana saw significant gains bumping pool many concurrent request.

update: question me understand tuning , tooling driver pool size rather troubleshoot immediate performance issue. described issue give question little context.

in scenarios this, first step start db.

if have queries slow respond, queries should appear in slow logs. take @ official docs profiling. default value "slow" queries 100ms, if slow queries because of db, see evidence there.

additionally, take @ graphs db. "the graphs", mean nagios/cacti/zabbix/serverdensity/mms charts of server doing. if not have these, start there. tweaking connection pool size useless if don't know how many connections have or cpu looks like.

any tools or strategies confirm or rule out driver connection pool size bottleneck?

once have ruled out db and have configured monitoring can open connection pool size. once have of in place. able tweak pool size , ensure have (a) solved problem , (b) not caused more problems.

the whole cycle important.

if muck connection pool you're not watching slow logs , total connections you'll cause more problems.