以上一節代碼為例，如何查看運行的線程數，需要調用threading模塊裏面的enumerate方法，返回一個線程數列表：

import threading
import time

"""以上一章的代碼為例，如何查看有多少個線程在運行"""


def sing():
    """唱歌5秒鐘"""
    for i in range(3):
        print(‘----------------‘)
        print(‘我在唱歌....‘)
        time.sleep(1)


def dance():
    for i in range(5):
        
 
print(‘我在跳舞....‘)
        print(‘----------------‘)
        time.sleep(1)


def main():
    t = threading.Thread(target=sing)  
    t2 = threading.Thread(target=dance)
    t.start()
    t2.start()
    # 循環打印正在運行的線程數，調用threading模塊中的enumerate方法返回一個列表，裏面的元素就是運行的線程，打印出元素個數就是線程數
    while True:
        nums 
 
= len(threading.enumerate())
        print(threading.enumerate())
        # 當沒有線程時，就退出
        if nums <= 1:
            break
        time.sleep(1)

if __name__ == ‘__main__‘:
    main()

運行結果如下：

我在唱歌....
我在跳舞....
[<_MainThread(MainThread, started 26264)>, <Thread(Thread-1, started 23804)>, <Thread(Thread-2, started 24216)>]
[<_MainThread(MainThread, started 26264)>, <Thread(Thread-1, started 23804)>, <Thread(Thread-2, started 24216)>]
我在跳舞....
我在唱歌....
[<_MainThread(MainThread, started 26264)>, <Thread(Thread-1, started 23804)>, <Thread(Thread-2, started 24216)>]
我在唱歌....
我在跳舞....
[<_MainThread(MainThread, started 26264)>, <Thread(Thread-1, started 23804)>, <Thread(Thread-2, started 24216)>]
我在跳舞....
[<_MainThread(MainThread, started 26264)>, <Thread(Thread-2, started 24216)>]
我在跳舞....
[<_MainThread(MainThread, started 26264)>, <Thread(Thread-2, started 24216)>]
[<_MainThread(MainThread, started 26264)>]

解釋如下圖：

網絡編程-線程-2、如何查看有多少個線程在運行