> 3. This issue is caught fairly easily by the race detector. Using a sync.Map or a lock around a map is pretty easy to communicate with other Go devs.

I run my Go development server with the -race flag as a default. If it affects performance I'll turn it off but that's very rare in practice. Unfortunately a lot of applications don't run tests against their HTTP endpoints (like only internal library stuff) which is bad bad bad, but the -race flag at least helps mitigate.

To anyone reading who cares:

1) Always run your tests with the -race flag!

2) Always write tests for your HTTP handling code too!

3) Run your dev server with -race for a week and see what happens.

This will hard crash your Go program and there is nothing you can do about it. You can't recover(). Go vet will not catch anything. The -race flag will!

  package main

  import "time"

  func main() {
   m := map[int]int{}
   go poop(m)
   go poop(m)
   time.Sleep(5 * time.Second)
  }

  func poop(m map[int]int) {
   for i := 0; i < 1e10; i++ {
    m[i] = i
   }
  }