多线程基础——python-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_44700741/article/details/129104540

本文展示了Python中使用threading模块创建多线程的三种方法：1)直接通过`threading.Thread`创建；2)继承`threading.Thread`定义子类；3)使用锁机制确保线程同步；4)介绍了线程池的概念，强调了线程池在资源管理中的优势。

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1、通过threading.Thread进行创建多线程，采用嵌套的方式（这里直接理解为了调用函数进行线程操作）

import threading
import time

#通过threading.Thread进行创建多线程
def target():
    print("the current threading %s is runing"
          % (threading.current_thread().name))
    time.sleep(1)
    print("the current threading %s is ended" % (threading.current_thread().name))


print("the current threading %s is runing" % (threading.current_thread().name))
## 属于线程t的部分
t = threading.Thread(target=target)
t.start()
## 属于线程t的部分
t.join()  # join是阻塞当前线程(此处的当前线程时主线程) 主线程直到Thread-1结束之后才结束
print("the current threading %s is ended" % (threading.current_thread().name))

输出结果：

the current threading MainThread is runing
the current threading Thread-1 is runing
the current threading Thread-1 is ended
the current threading MainThread is ended

2、#通过继承threading.Thread定义子类创建多线程。

例子：线程1和线程2交叉进行

import threading
import time
#通过继承threading.Thread定义子类创建多线程
class myThread(threading.Thread):  # 继承父类threading.Thread
   def __init__(self, threadID, name, counter):
      threading.Thread.__init__(self)
      self.threadID = threadID
      self.name = name
      self.counter = counter

   def run(self):  # 把要执行的代码写到run函数里面 线程在创建后会直接运行run函数
      print("Starting " + self.name)
      print_time(self.name, self.counter, 5)
      print("Exiting " + self.name)


def print_time(threadName, delay, counter):
   while counter:
      time.sleep(delay)
      print("%s process at: %s" % (threadName, time.ctime(time.time())))
      counter -= 1


# 创建新线程
thread1 = myThread(1, "Thread-1", 1)
thread2 = myThread(2, "Thread-2", 2)

# 开启线程
thread1.start()
thread2.start()

# 等待线程结束
thread1.join()
thread2.join()

print("Exiting Main Thread")

输出结果：

Starting Thread-1
Starting Thread-2
Thread-1 process at: Sat Feb 18 20:56:01 2023
Thread-1 process at: Sat Feb 18 20:56:02 2023Thread-2 process at: Sat Feb 18 20:56:02 2023

Thread-1 process at: Sat Feb 18 20:56:03 2023
Thread-2 process at: Sat Feb 18 20:56:04 2023
Thread-1 process at: Sat Feb 18 20:56:04 2023
Thread-1 process at: Sat Feb 18 20:56:05 2023
Exiting Thread-1
Thread-2 process at: Sat Feb 18 20:56:06 2023
Thread-2 process at: Sat Feb 18 20:56:08 2023
Thread-2 process at: Sat Feb 18 20:56:10 2023
Exiting Thread-2
Exiting Main Thread

3、为了防止线程1和线程2同时进行的过程中导致数据发生了改变。因此，通过locker类对其中一个线程进行加锁。

import threading
import time

#通过threadLock使得线程一个一个的进行
class myThread(threading.Thread):
    def __init__(self, threadID, name, counter):
        threading.Thread.__init__(self)
        self.threadID = threadID
        self.name = name
        self.counter = counter

    def run(self):
        print("Starting " + self.name)
        # 获得锁，成功获得锁定后返回True
        # 可选的timeout参数不填时将一直阻塞直到获得锁定
        # 否则超时后将返回False
        threadLock.acquire()
        print_time(self.name, self.counter, 5)
        # 释放锁
        threadLock.release()


def print_time(threadName, delay, counter):
    while counter:
        time.sleep(delay)
        print("%s: %s" % (threadName, time.ctime(time.time())))
        counter -= 1


threadLock = threading.Lock()
threads = []
# 创建新线程
thread1 = myThread(1, "Thread-1", 1)
thread2 = myThread(2, "Thread-2", 2)
# 开启新线程
thread1.start()
thread2.start()
# 添加线程到线程列表
threads.append(thread1)
threads.append(thread2)
# 等待所有线程完成
for t in threads:
    t.join()

print("Exiting Main Thread")

输出结果：可以看到这里将线程1先运行完，然后运行线程2

Starting Thread-1
Starting Thread-2
Thread-1: Sat Feb 18 20:59:13 2023
Thread-1: Sat Feb 18 20:59:14 2023
Thread-1: Sat Feb 18 20:59:15 2023
Thread-1: Sat Feb 18 20:59:16 2023
Thread-1: Sat Feb 18 20:59:17 2023
Thread-2: Sat Feb 18 20:59:19 2023
Thread-2: Sat Feb 18 20:59:21 2023
Thread-2: Sat Feb 18 20:59:23 2023
Thread-2: Sat Feb 18 20:59:25 2023
Thread-2: Sat Feb 18 20:59:27 2023
Exiting Main Thread