What is the value of r after the second panic call?

Question

go

There is a code

package main

import "log"

func f() {
  defer func() {
    if r := recover(); r != nil {
      log.Printf("recover:%#v", r)
    }
  }()
  panic(1)
  panic(2)
}

func main() {
  f()
}

As I understand it, the first panic is processed correctly, while the second one is no longer processed, am I right?

Answer 1

The execution of the f() function ends after the first panic, then it executes defer.
The second panic will not be executed, because The execution of the function has already ended and the queue will not reach it.
You can add some log.Println to your example and follow the progress like this

package main

import "log"

func f() {
  defer func() {
    if r := recover(); r != nil {
      log.Printf("recover:%#v", r)
    }
  }()
  log.Println("Start first panic")
  panic(1)
  log.Println("After first panic")
  panic(2)
  log.Println("After second panic")
}

func main() {
  f()
  log.Println("After f()")
}

The output will be like this

2020/07/20 23:14:07 Start first panic
2020/07/20 23:14:07 recover:1
2020/07/20 23:14:07 After f()