Juan Carlos García Martínez thewraven

Channels Are Not Enough

... or Why Pipelining Is Not That Easy

Golang Concurrency Patterns for brave and smart.

Intro

There are three easy to make mistakes in go. I present them here in the way they are often found in the wild, not in the way that is easiest to understand.

All three of these mistakes have been made in Kubernetes code, getting past code review at least once each that I know of.

Loop variables are scoped outside the loop.

What do these lines do? Make predictions and then scroll down.

func print(pi *int) { fmt.Println(*pi) }

Proposal: Eliminate STW stack re-scanning

Author(s): Austin Clements, Rick Hudson

Last updated: 2016-10-18

Discussion at https://golang.org/issue/17503.

Abstract

Ideas on generics in Go

As we all know, Go 2 is on its way and despite the hesitations, it's clear that without generics, it would end up being a disappointment. And although we are still gathering real-life use-cases, or experience reports, there's nothing bad about starting to think about how generics in Go could look like. I've come up with a few ideas which I'd love to share. So, here we go!

What's already achievable?

Now, Go 1 has no generics, but has interfaces. Interfaces (sometime accompanied by reflection)

	Latency Comparison Numbers (~2012)
	----------------------------------
	L1 cache reference 0.5 ns
	Branch mispredict 5 ns
	L2 cache reference 7 ns 14x L1 cache
	Mutex lock/unlock 25 ns
	Main memory reference 100 ns 20x L2 cache, 200x L1 cache
	Compress 1K bytes with Zippy 3,000 ns 3 us
	Send 1K bytes over 1 Gbps network 10,000 ns 10 us
	Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD