Python3 time.sleep()行为反常

Question

L.S，

我正在尝试学习python(3)，并且对time.sleep()的行为感到困惑，我在rpi3b上运行raspbian。

#!/usr/bin/python3
import bluetooth
import sys
import time
_shuttermac ="11:22:33:44:5D:6A"
while True:
    # check if the device is switched on by mac address lookup
    print("Checking " + time.strftime("%a, %d %b %Y %H:%M:%S - ", time.gmtime()),end ="")
    result = bluetooth.lookup_name(_shuttermac, timeout=5)
    #print(result)
    if (result != None):
        print("Device detected by bluetooth mac lookup")
    else:
        print("Device with MAC " + _shuttermac + " NOT detected")
    time.sleep(1)   # check every 5 secs if device comes online      
sys.exit()

输出

Checking Thu, 25 Jun 2020 11:21:02 - Device with MAC 11:22:33:44:5D:6A NOT detected
Checking Thu, 25 Jun 2020 11:21:08 - Device with MAC 11:22:33:44:5D:6A NOT detected
Checking Thu, 25 Jun 2020 11:21:14 - Device with MAC 11:22:33:44:5D:6A NOT detected
Checking Thu, 25 Jun 2020 11:21:20 - Device with MAC 11:22:33:44:5D:6A NOT detected
Checking Thu, 25 Jun 2020 11:21:26 - Device with MAC 11:22:33:44:5D:6A NOT detected

如您所见，输出语句间隔为6秒，而不是编码的1。

我哪里出错了？

Answer 1

6秒间隔是因为当查找失败时，while True的每个循环都会执行两个耗时的操作：

1. bluetooth.lookup_name(_shuttermac, timeout=5)有5秒的超时时间。如果快速找到它，它应该完成faster
2. time.sleep(1)暂停整个Python程序1秒的

。

您可以缩短bluetooth.lookup_name的超时时间和sleep()持续时间。这可能会给查找的准确性带来意想不到的后果(我对它不太熟悉)。