如何不等功能完成python

Question

I'm trying to program a loop with a asynchronous part in it. I dont want to wait for this asynchronous part every iteration though. Is there a way to not wait for this function inside the loop to finish?

In code (example):

import time
def test():
    global a
    time.sleep(1)
    a += 1
    test()

global a
a = 10
test() 
while(1):
    print a

Thanks in advance!

Answer 1

You can put it in a thread. Instead of test()

from threading import Thread
Thread(target=test).start()
print("this will be printed immediately")

Answer 2

A simple way is to run test() in another thread

import threading

th = threading.Thread(target=test)
th.start()

Answer 3

You should look at a library meant for asynchronous requests, such as gevent

Examples here: http://sdiehl.github.io/gevent-tutorial/#synchronous-asynchronous-execution

import gevent

def foo():
    print('Running in foo')
    gevent.sleep(0)
    print('Explicit context switch to foo again')

def bar():
    print('Explicit context to bar')
    gevent.sleep(0)
    print('Implicit context switch back to bar')

gevent.joinall([
    gevent.spawn(foo),
    gevent.spawn(bar),
])

Answer 4

use thread . it creates a new thread in that the asynchronous function runs

https://www.tutorialspoint.com/python/python_multithreading.htm

Answer 5

To expand on blue_note, let's say you have a function with arguments:

def test(b):
    global a
    time.sleep(1)
    a += 1 + b

You need to pass in your args like this:

from threading import Thread
b = 1
Thread(target=test, args=(b, )).start()
print("this will be printed immediately")

Note args must be a tuple.