package main

import (
  "context"
  "log"
  "os"
  "os/signal"
  "syscall"
  "time"
)

func a(ctx context.Context) {
  <-ctx.Done()
  log.Print("Close a")
}

func b(ctx context.Context, cancel context.CancelFunc) {
  defer func() {
    if v := recover(); v != nil {
      cancel()
    }
  }()
  time.Sleep(2 * time.Second)
  log.Panic("Dead")
  log.Print("afterlife")
}

func main() {
  defer log.Print("Shutdown")
  ctx, cancel := context.WithCancel(context.Background())
  // defer func() {
  //   if v := recover(); v != nil {
  //     cancel()
  //   }
  // }()
  intCh := make(chan os.Signal, 1)
  signal.Notify(intCh, os.Interrupt, os.Kill, syscall.SIGTERM)
  go a(ctx)
  go b(ctx, cancel)

  select {
  case <-ctx.Done():
    log.Println("Context is dead")
  case <-time.After(10 * time.Second):
    log.Println("timeout 2")
  case <-intCh:
    log.Println("Int")
  }
  log.Print("End")
  cancel()
  time.Sleep(100 * time.Microsecond)
}