在 Python 中创建线程

问题描述：

我有一个脚本，我希望一个函数与另一个函数同时运行。

我看过的示例代码：

import threading

def MyThread (threading.thread):
    # doing something........

def MyThread2 (threading.thread):
    # doing something........

MyThread().start()
MyThread2().start()

我无法让它正常工作。我更愿意使用线程函数而不是类来实现它。

这是工作脚本：

from threading import Thread

class myClass():

    def help(self):
        os.system('./ssh.py')

    def nope(self):
        a = [1,2,3,4,5,6,67,78]
        for i in a:
            print i
            sleep(1)


if __name__ == "__main__":
    Yep = myClass()
    thread = Thread(target = Yep.help)
    thread2 = Thread(target = Yep.nope)
    thread.start()
    thread2.start()
    thread.join()
    print 'Finished'

解决方案 1：

您不需要使用子类Thread来实现这一点 - 请看我下面发布的简单示例以了解如何操作：

from threading import Thread
from time import sleep

def threaded_function(arg):
    for i in range(arg):
        print("running")
        sleep(1)


if __name__ == "__main__":
    thread = Thread(target = threaded_function, args = (10, ))
    thread.start()
    thread.join()
    print("thread finished...exiting")

这里我展示了如何使用线程模块创建一个线程，该线程将调用一个普通函数作为其目标。您可以看到我如何在线程构造函数中向它传递我需要的任何参数。

解决方案 2：

您的代码存在一些问题：

def MyThread ( threading.thread ):

• 不能用函数作为子类，只能用类作为子类

• 如果你要使用子类，你需要的是threading.Thread，而不是threading.thread

如果您确实只想使用函数来执行此操作，则有两个选择：

和threading：

import threading
def MyThread1():
    pass
def MyThread2():
    pass

t1 = threading.Thread(target=MyThread1, args=[])
t2 = threading.Thread(target=MyThread2, args=[])
t1.start()
t2.start()

和_thread：

import _thread
def MyThread1():
    pass
def MyThread2():
    pass

_thread.start_new_thread(MyThread1, ())
_thread.start_new_thread(MyThread2, ())

_thread.start_new_thread文档

解决方案 3：

我尝试添加另一个 join()，它似乎有效。以下是代码

from threading import Thread
from time import sleep

def function01(arg,name):
    for i in range(arg):
        print(name,'i---->',i,'
')
        print (name,"arg---->",arg,'
')
        sleep(1)

def test01():
    thread1 = Thread(target = function01, args = (10,'thread1', ))
    thread1.start()
    thread2 = Thread(target = function01, args = (10,'thread2', ))
    thread2.start()
    thread1.join()
    thread2.join()
    print ("thread finished...exiting")

test01()

解决方案 4：

使用实现多线程进程的简单方法threading

相同的代码片段

import threading

#function which takes some time to process 
def say(i):
    time.sleep(1)
    print(i)

threads = []
for i in range(10):
    
    thread = threading.Thread(target=say, args=(i,))

    thread.start()
    threads.append(thread)

#wait for all threads to complete before main program exits 
for thread in threads:
    thread.join()

解决方案 5：

Python 3 具有启动并行任务的功能。这使我们的工作更加轻松。

它具有线程池和进程池。

以下给出了一个见解：

ThreadPoolExecutor 示例

import concurrent.futures
import urllib.request

URLS = ['http://www.foxnews.com/',
        'http://www.cnn.com/',
        'http://europe.wsj.com/',
        'http://www.bbc.co.uk/',
        'http://some-made-up-domain.com/']

# Retrieve a single page and report the URL and contents
def load_url(url, timeout):
    with urllib.request.urlopen(url, timeout=timeout) as conn:
        return conn.read()

# We can use a with statement to ensure threads are cleaned up promptly
with concurrent.futures.ThreadPoolExecutor(max_workers=5) as executor:
    # Start the load operations and mark each future with its URL
    future_to_url = {executor.submit(load_url, url, 60): url for url in URLS}
    for future in concurrent.futures.as_completed(future_to_url):
        url = future_to_url[future]
        try:
            data = future.result()
        except Exception as exc:
            print('%r generated an exception: %s' % (url, exc))
        else:
            print('%r page is %d bytes' % (url, len(data)))

另一个例子

import concurrent.futures
import math

PRIMES = [
    112272535095293,
    112582705942171,
    112272535095293,
    115280095190773,
    115797848077099,
    1099726899285419]

def is_prime(n):
    if n % 2 == 0:
        return False

    sqrt_n = int(math.floor(math.sqrt(n)))
    for i in range(3, sqrt_n + 1, 2):
        if n % i == 0:
            return False
    return True

def main():
    with concurrent.futures.ThreadPoolExecutor(max_workers=5) as executor:
        for number, prime in zip(PRIMES, executor.map(is_prime, PRIMES)):
            print('%d is prime: %s' % (number, prime))

if __name__ == '__main__':
    main()

解决方案 6：

您可以使用构造函数target中的参数Thread直接传入被调用的函数，而不是run。

解决方案 7：

您是否重写了 run() 方法？如果重写了__init__，您是否确保调用了基类threading.Thread.__init__()？

启动两个线程后，主线程是否会继续无限期地在子线程上工作/阻止/加入，以便主线程执行不会在子线程完成其任务之前结束？

最后，您是否遇到任何未处理的异常？