xuewei_semaphore = threading.Semaphore(4) #申請(qǐng)信號(hào)量

#在某個(gè)地方使用信號(hào)量
xuewei_semaphore.acquire()

//do something here
....

xuewei_semaphore.release()

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# @Time : 2021/11/27 10:43 下午
# @Author : LeiXueWei
# @CSDN/Juejin/Wechat: 雷學(xué)委
# @XueWeiTag: CodingDemo
# @File : threading_semephore.py
# @Project : hello
import threading
import time
import queue

xuewei_semaphore = threading.Semaphore(4)

print("xuewei_semaphore:", xuewei_semaphore)

waiting_for_train = {"value": 0}


def run():
    new_joiner = threading.current_thread().name
    # print(" %s ready" %new_joiner )
    xuewei_semaphore.acquire()
    print(" %s go" % new_joiner)
    waiting_for_train['value'] += 1
    time.sleep(1)
    print(" %s completed" % threading.current_thread().name)
    xuewei_semaphore.release()
    waiting_for_train['value'] -= 1


def log_the_waiting_area_status():
    while True:
        time.sleep(0.5)
        name = threading.current_thread().name
        print("name %s - size %s " % (name, waiting_for_train['value']))


q_watcher = threading.Thread(name="waiting area", target=log_the_waiting_area_status)
q_watcher.start()
threads = []
for i in range(100):
    t_name = "t-" + str(i)
    t = threading.Thread(name=t_name, target=run)
    threads.append(t)
    t.start()

for t in threads:
    t.join()

xuewei_semaphore.acquire()
print(" %s go" % new_joiner)
waiting_for_train['value'] += 1
time.sleep(1)
waiting_for_train['value'] -= 1
print(" %s completed" % threading.current_thread().name)
xuewei_semaphore.release()