浅谈python多线程和多线程变量共享问题介绍

import threading
import time
class ClassName(threading.Thread):
	"""创建类，通过多线程执行"""
	def run(self):
		for i in range(5):
			print(i)
			time.sleep(1)

def sing():
	for i in range(1,11):
		print("唱歌第 %d 遍" % i)
		time.sleep(1)

def dance():
	for i in range(1,16):
		print("跳舞第 %d 遍" % i)
		time.sleep(1)

def main():
	t1 = threading.Thread(target = sing)
	t2 = threading.Thread(target = dance)
	t = ClassName()
	
	# 启动线程
	t1.start()
	t2.start()
	t.start()

	while True:
		length = len(threading.enumerate())
		print("正在运行的线程有 %s" %threading.enumerate())
	
		if length <= 1:
			break
		time.sleep(1)

if __name__ == '__main__':
	main()

import threading
import time

#定义全局变量
g_num = 0

def test1():
	"""函数test1对全局变量进行更改"""
	global g_num
	for i in range(1,10):
		g_num += 1

	print("--- test1 线程 g_num = %d--- " % g_num)

def test2():
	"""函数test2 打印全局变量"""
	print("--- test2 线程 g_num = %d--- " % g_num)

def main():
	t1 = threading.Thread(target=test1)
	t2 = threading.Thread(target=test2)

	# 启动线程
	t1.start()
	# 增加睡眠是为了保证优先执行函数test1
	time.sleep(1)
	t2.start()

	print("--- 主线程 g_num = %d--- " % g_num)

if __name__ == '__main__':
	main()

import threading
import time

# 定义全局变量
g_num = 0

def test1(num):
	"""函数test1对全局变量进行更改"""
	global g_num
	for i in range(num):
		g_num += 1

	print("test1 线程 g_num = %d---" % g_num)

def test2(num):
	"""函数test2对全局变量进行更改"""
	global g_num
	for i in range(num):
		g_num += 1

	print("tes2 线程 g_num = %d---" % g_num)

def main():
	t1 = threading.Thread(target=test1, args=(1000000, ))
	t2 = threading.Thread(target=test2, args=(1000000, ))

	t1.start()
	t2.start()

	time.sleep(1)
	print("主线程 g_num = %d---" % g_num)

if __name__ == '__main__':
	main()

import threading
import time

# 创建变量
g_num = 0
# 创建锁默认为开锁状态
mutex = threading.Lock()

def test1(num):
	global g_num
	for i in range(num):
		# 上锁
		mutex.acquire()
		g_num += 1
		# 解锁
		mutex.release()
	print("--- test1 线程 g_num = %d---" % g_num)

def test2(num):
	global g_num
	for i in range(num):
		# 上锁
		mutex.acquire()
		g_num += 1
		# 解锁
		mutex.release()

	print("--- test2 线程 g_num = %d---" % g_num)

def main():
	t1 = threading.Thread(target=test1, args=(1000000, ))
	t2 = threading.Thread(target=test2, args=(1000000, ))

	t1.start()
	t2.start()

	time.sleep(1)
	print("--- 主线程 g_num = %d---" % g_num)

if __name__ == '__main__':
	main()

import threading
import time

# 创建两个锁A, B
mutexA = threading.Lock()
mutexB = threading.Lock()

def test1():
	# 对muctexA上锁
	mutexA.acquire()

	# mutexA上锁后，延时1秒，等待mutexB上锁
	print("test1 ---do1---up---")
	time.sleep(1)
	# 此时会堵塞，因为mutexB已经上锁
	mutexB.acquire()
	print("test1 ---do1---down---")
	mutexB.release()

	# 对mutexA解锁
	mutexA.release()

def test2():
	# 对muctexB上锁
	mutexB.acquire()

	# mutexB上锁后，延时1秒，等待mutexA上锁
	print("test2 ---do1---up---")
	time.sleep(1)
	# 此时会堵塞，因为mutexB已经上锁
	mutexA.acquire()
	print("test2 ---do1---down---")
	mutexA.release()

	# 对mutexA解锁
	mutexB.release()

def main():
	t1 = threading.Thread(target=test1)
	t2 = threading.Thread(target=test2)

	t1.start()
	t2.start()


if __name__ == '__main__':
	main()