我在文档同步中读到了异常 case .结论:
由于等待时C.L未锁定，因此调用方通常 当WAIT返回时，不能假定条件为真.相反， 调用方应该循环等待:
c.L.Lock()
for !condition() {
c.Wait()
}
... make use of condition ...
c.L.Unlock()
我不明白这是怎么回事.例如，在我的代码中，我是否需要有循环？
func subscribe(name string, data map[string]string, c *sync.Cond) {
c.L.Lock()
for len(data) != 0 {
c.Wait()
}
fmt.Printf("[%s] %s\n", name, data["key"])
c.L.Unlock()
}
func publish(name string, data map[string]string, c *sync.Cond) {
time.Sleep(time.Second)
c.L.Lock()
data["key"] = "value"
c.L.Unlock()
fmt.Printf("[%s] data publisher\n", name)
c.Broadcast()
}
func main() {
data := map[string]string{}
cond := sync.NewCond(&sync.Mutex{})
wg := sync.WaitGroup{}
wg.Add(3)
go func() {
defer wg.Done()
subscribe("subscriber_1", data, cond)
}()
go func() {
defer wg.Done()
subscribe("subscriber_2", data, cond)
}()
go func() {
defer wg.Done()
publish("publisher", data, cond)
}()
wg.Wait()
}