Go

Version History

Date	Description
Nov 5, 2021	Initial

I decided to learn Go and use it build some sample projects. I may just start from a simple webserver. Since Go is used a lot in virtualization part (e.g., Docker, gVisor) and databases (mangoDB?), I’m thinking of doing along that line as well.

The learning code will be pushed into https://github.com/lastweek/learn-go.

Resources

• awesome-go
• gVisor

Notes

Function call pass by value or reference

For function call, the following are passed by value: a) struct b) basic data type (e.g., int). So the function receives a copy of each argument; modifications to the copy do not affect the caller. However, the following are pointer like: pointers (to struct, int), slice, map, function, or channel. The caller may be affected by any modifications the function makes to variable indirectly referred to by the argument. (Some testing code here https://github.com/lastweek/learn-go/blob/master/playground/datatypes.go)

Defer

Defer is one of my favorite featues of Go. I have bad memories on maintaining the error handling code in C, especially in kernel: I have to carefully order the error handling code at the end of function, have proper labels and write proper goto. Here, defer elegantly solves this complex error handling issue.

Goroutine

Stack: a goroutine usually has a small stack typically 2KB. But unlike an OS thread, a goroutine’s stack is not fixed; it grows and shrinks as needed. It could beas much as 1GB.

Scheduling: what’s the policy there? Does the runtime use some sort of timer if user code is not giving up control? It is an M:N scheduler. Some internal documentation: https://github.com/golang/go/blob/master/src/runtime/HACKING.md

Go Runtime

The source code is here under this directory src/runtime. A huge directory with a lot of files. Why not create more subdirectories to better organize all these files?