Golang与python线程详解及简单实例
在GO中,开启15个线程,每个线程把全局变量遍历增加100000次,因此预测结果是 15*100000=1500000.
var sum int
var cccc int
var m *sync.Mutex
func Count1(i int, ch chan int) {
for j := 0; j < 100000; j++ {
cccc = cccc + 1
}
ch <- cccc
}
func main() {
m = new(sync.Mutex)
ch := make(chan int, 15)
for i := 0; i < 15; i++ {
go Count1(i, ch)
}
for i := 0; i < 15; i++ {
select {
case msg := <-ch:
fmt.Println(msg)
}
}
}
但是最终的结果,406527
说明需要加锁。
func Count1(i int, ch chan int) {
m.Lock()
for j := 0; j < 100000; j++ {
cccc = cccc + 1
}
ch <- cccc
m.Unlock()
}
最终输出:1500000
python中:同样方式实现,也不行。
count = 0
def sumCount(temp):
global count
for i in range(temp):
count = count + 1
li = []
for i in range(15):
th = threading.Thread(target=sumCount, args=(1000000,))
th.start()
li.append(th)
for i in li:
i.join()
print(count)
输出结果:3004737
说明也需要加锁:
mutex = threading.Lock()
count = 0
def sumCount(temp):
global count
mutex.acquire()
for i in range(temp):
count = count + 1
mutex.release()
li = []
for i in range(15):
th = threading.Thread(target=sumCount, args=(1000000,))
th.start()
li.append(th)
for i in li:
i.join()
print(count)
输出1500000
OK,加锁的小列子。
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