在 python 中创建线程

Question

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()

我无法正常工作。我更愿意使用线程函数而不是类来实现这一点。

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'

Answer 1

您不需要使用 Thread 的子类来完成这项工作 - 看看我在下面发布的简单示例，看看如何：

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来创建一个调用普通函数作为其目标的线程。你可以看到我如何在线程构造函数中传递我需要的任何参数。

Answer 2

您的代码存在一些问题：

def MyThread ( threading.thread ):

• 您不能使用函数进行子类化；只用一个类
• 如果您要使用子类，则需要 threading.Thread，而不是 threading.thread

如果你真的想只使用函数，你有两个选择：

带线程：

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

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

带线程：

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

thread.start_new_thread(MyThread1, ())
thread.start_new_thread(MyThread2, ())

thread.start_new_thread 的文档

Answer 3

我尝试添加另一个 join()，它似乎有效。这是代码

from threading import Thread
from time import sleep

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

Answer 4

您可以在Thread 构造函数中使用target 参数直接传入一个被调用的函数，而不是run。

Answer 5

你是否重写了 run() 方法？如果你覆盖了__init__，你确定调用基础threading.Thread.__init__()吗？

在启动两个线程后，主线程是否继续对子线程进行无限期的工作/阻塞/加入，以使主线程执行在子线程完成任务之前不会结束？

最后，您是否遇到任何未处理的异常？

Answer 6

Python 3 具有Launching parallel tasks 的功能。这使我们的工作更轻松。

它适用于thread pooling 和Process pooling。

下面给出一个见解：

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()

Answer 7

使用threading实现多线程进程的简单方法

同样的代码sn-p

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()