Gnatsd: a high performance NATS messaging server written in Go(github.com)

33 pointsby krobertsonvor 13 Jahren7 comments

Gnatsd: a high performance NATS messaging server written in Go

https://github.com/apcera/gnatsd

3 comments

DrJosiahvor 13 Jahren

This is probably a bit off topic, but I notice that they implemented their own hashmap with pluggable hash functions. Awesome in theory (and practice), though I notice that the performance of their custom hash table is poorer than Go's built-in hash map (Go's hashmap takes 1/2, 3/4, and 9/10th the time of their hashmap for small, medium, and large keys, respectively - though this could be related to the updated aes hash in Go, and that my processor supports it).

While looking through the implementations, the Gnatsd hashmap implementation is a simple table with buckets, where as the Go hashmap also uses a table with buckets, though each "bucket" has 8 slots by default (and does subsequent chaining). Go's chunking of buckets helps caches work better, reduces random reads, and helps to minimize overhead (fewer pointers if you have fixed-size data). Read the first 83 lines of http://golang.org/src/pkg/runtime/hashmap.c to see what good structure design and experimentation gets you.

Does someone have an example where a 'go test --bench="." -gcflags="-B"' call in the gnatsd/hashmap path actually comes out ahead for the Gnatsd hashmap using a recent Go?

krobertsonvor 13 Jahren

Derek's hashmap was faster than than Go 1.0's built in hashmap. With Go 1.1 or 1.1.1 (don't remember which one exactly), the standard one did become faster, though Derek had decided to stick with it as is. I can ask him what the reason was... I don't recall right now.

DrJosiahvor 13 Jahren

I think I may know why they are sticking with the self-built version: random key selection. The built-in hash map doesn't include a method to discover a random key, but the gnatsd hashmap does.

clumsysmurfvor 13 Jahren

At first glance, NATS looks similar in goal to MQTT. Can anyone describe the differences?

jvoorhisvor 13 Jahren

NATS is the pub-sub messaging protocol and implementation created by Derek Collision, who architected the first iteration of Cloud Foundry. It is a simple pub-sub service at its core, but the Ruby and NodeJS clients implement various messaging patterns similar to what is supported by ZeroMQ. It is used extensively within Cloud Foundry.

stock_toastervor 13 Jahren

After some googling, I found this description here[1]. It sounds like a straightforward pub-sub server (similar to redis pub/sub?).

  [1]: http://www.activestate.com/blog/2013/01/building-paas-ruby

orenmazorvor 13 Jahren

at first I definitely thought this was related to the old gnu bug tracker.