python3.2.2 增加了一个新的并发库

用过java并发框架的人可能看过后就乐了.

这个库很精简,主要有两个核心类: Executor and Future,Executor用来接收异步任务(包含参数),并返回一个Future.

Executor

submit(fn, *args, **kwargs)
map(func, *iterables, timeout=None)
shutdown(wait=True)

Executor还有两个子类ThreadPoolExecutor,ProcessPoolExecutor

Future Objects

cancel()
cancelled()
running()
done()
result(timeout=None)
exception(timeout=None)
add_done_callback(fn)

看两个例子:
Check Prime Example

from concurrent import 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 futures.ProcessPoolExecutor() as executor:
        for number, prime in zip(PRIMES, executor.map(is_prime,
                                                      PRIMES)):
            print('%d is prime: %s' % (number, prime))

if __name__ == '__main__':
    main()

Web Crawl Example

from concurrent import 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/']

def load_url(url, timeout):
    return urllib.request.urlopen(url, timeout=timeout).read()

def main():
    with futures.ThreadPoolExecutor(max_workers=5) as executor:
        future_to_url = dict(
            (executor.submit(load_url, url, 60), url)
             for url in URLS)

        for future in futures.as_completed(future_to_url):
            url = future_to_url[future]
            try:
                print('%r page is %d bytes' % (
                          url, len(future.result())))
            except Exception as e:
                print('%r generated an exception: %s' % (
                          url, e))

if __name__ == '__main__':
    main()