Python多线程

2021-07-08

使用threading库写了些Python多线程的简单demo，方便以后使用。

1. 定义两个线程

import threading, time

# target function
def run(task_name, sleep_time):
    start_time = time.time()
    print('run task', task_name)
    time.sleep(sleep_time)
    print('task', task_name, 'done,', 'time:', time.time()-start_time)

start_time = time.time()

t1 = threading.Thread(target=run, args=('t1', 2))
t2 = threading.Thread(target=run, args=('t2', 4))

t1.start()
t2.start()
t1.join()
t2.join()

print('total time:', time.time()-start_time)

执行结果：

task t1 start
task t2 start
task t1 done, time: 2.002859115600586
task t2 done, time: 4.001489162445068
total time: 4.002847194671631

其中一个进程为2秒，另一个为4秒，两个进程一共使用了4秒的时间

2. 使用for循环开启多个线程

import threading, time

# target function
def run(task_name, sleep_time):
    # start_time = time.time()
    # print('task', task_name, 'start')
    time.sleep(sleep_time)
    # print('task', task_name, 'done,', 'time:', time.time()-start_time)

start_time = time.time()
t_obj=[]
for i in range(50):
    t = threading.Thread(target=run, args=("t-%s"%i, 2))
    t_obj.append(t)
    t.start()

for t in t_obj:
    t.join()

print('total time:', time.time()-start_time)

执行结果：

1	total time: 2.010349988937378

其中每个进程执行2秒，50个进程一共也仅需要2秒多一点点的时间。

3. 继承threading.Thread类实现多线程

import threading, time

class MyThread(threading.Thread):
    def __init__(self, task_name, sleep_time):
        super(MyThread, self).__init__()
        self.task_name = task_name
        self.sleep_time = sleep_time
    def run(self):
        start_time = time.time()
        print('task', self.task_name, 'start')
        time.sleep(self.sleep_time)
        print('task',self.task_name, 'done,', 'time:', time.time()-start_time)

start_time = time.time()

t1 = MyThread('t1', 2)
t2 = MyThread('t2', 4)

t1.start()
t2.start()
t1.join()
t2.join()

print('total time:', time.time() - start_time)

执行结果：

run task t1
run task t2
task t1 done, time: 2.001649856567383
task t2 done, time: 4.001299858093262
total time: 4.002930164337158

与第一个实验类似，开启了两个进程，其中一个进程为2秒，另一个为4秒，两个进程一共使用了4秒。

参考

python之多线程