问题:在python中创建线程
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()
我在进行这项工作时遇到了麻烦。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'
回答 0
您无需使用的子类Thread
即可完成这项工作-请看一下我在下面发布的简单示例,了解如何:
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")
在这里,我展示了如何使用线程模块创建一个线程,该线程调用普通函数作为其目标。您可以看到如何在线程构造函数中将所需的任何参数传递给它。
回答 1
您的代码存在一些问题:
def MyThread ( threading.thread ):
- 您不能使用函数子类化;只有一个Class
- 如果要使用子类,则需要threading.Thread,而不是threading.thread
如果您真的只想使用函数来执行此操作,则有两个选择:
使用线程:
import threading
def MyThread1():
pass
def MyThread2():
pass
t1 = threading.Thread(target=MyThread1, args=[])
t2 = threading.Thread(target=MyThread2, args=[])
t1.start()
t2.start()
带螺纹:
import thread
def MyThread1():
pass
def MyThread2():
pass
thread.start_new_thread(MyThread1, ())
thread.start_new_thread(MyThread2, ())
回答 2
我试图添加另一个join(),似乎可行。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()
回答 3
您可以target
在Thread
构造函数中使用参数直接传递被调用而不是的函数run
。
回答 4
您是否覆盖了run()方法?如果您改写了__init__
,您确定要呼叫基地threading.Thread.__init__()
吗?
启动两个线程后,主线程是否继续在子线程上无限期地工作/阻塞/联接,以使主线程在子线程完成其任务之前不会结束执行?
最后,您是否遇到任何未处理的异常?
回答 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。
以下提供了一个见解:
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()