package main
import ( "fmt"
"sync"
"time")var gRWLock *sync.RWMutexvar gVar intfunc init() {
gRWLock = new(sync.RWMutex)
gVar = 1}
func main() { var wg sync.WaitGroup
go Read(1, &wg)
wg.Add(1)
go Write(1, &wg)
wg.Add(1)
go Read(2, &wg)
wg.Add(1)
go Read(3, &wg)
wg.Add(1)
wg.Wait()
}
func Read(id int, wg *sync.WaitGroup) {
fmt.Printf("Read Coroutine: %d start\n", id)
defer fmt.Printf("Read Coroutine: %d end\n", id)
gRWLock.RLock()
fmt.Printf("gVar %d\n", gVar)
time.Sleep(time.Second)
gRWLock.RUnlock()
wg.Done()
}
func Write(id int, wg *sync.WaitGroup) {
fmt.Printf("Write Coroutine: %d start\n", id)
defer fmt.Printf("Write Coroutine: %d end\n", id)
gRWLock.Lock()
gVar = gVar + 100
fmt.Printf("gVar %d\n", gVar)
time.Sleep(time.Second)
gRWLock.Unlock()
wg.Done()
}
