How to recover from concurrent map writes?

Question

How do you recover from a runtime panic on a \"concurrent map read and map write\"? The usual defer with recover doesn\'t seem to work. Why is that?

I know that you

Answer 1

Do not recover, guard your code with mutexes form package sync.

package main

import (
    "sync"
    "time"
)

var m = make(map[string]string)
var l = sync.Mutex{}

func main() {
    go func() {
        for {
            l.Lock()
            m["x"] = "foo"
            l.Unlock()
        }
    }()
    go func() {
        for {
            l.Lock()
            m["x"] = "foo"
            l.Unlock()
        }
    }()

    time.Sleep(1 * time.Second)
}