Node 0.8.9 to 0.10.21 cpu impact.

[vsm83]

I've got one-thread server on amazon aws (x-large) which use "net" TCP server, having about 2700 open active sockets in peak time.
When sockets count raising to 2800, cpu load is 100% and database connections (pg module) begin lagging.
But when I`ve changed node version down to 0.8.9, CPU usage decreased to 20% (with periodic 100% GC peaks)
What's happened with node 0.10.21?
All config options are default.

[bnoordhuis]

Hard to say unless you have a test case or example app that uses core modules only (which doesn't seem to be the case as you mention the pg module.) Please use the mailing list for more support.

[vsm83]

I used profiler "nodetime".
With profiler I`ve found that in v.0.10.21 the most of CPU used for exports._unrefActive in timer.js, but in v. 0.8.9 there is no exports._unrefActive

[bnoordhuis]

_unrefActive() was added in v0.10.10 in commit f46ad01 and is a known bottleneck. It's scheduled for optimization in v0.12. Commit joyent/libuv@21c37a7 from earlier this week is one such optimization.