concurrent.futures --- 启动并行任务 — Python 3.7.13 文档
concurrent.futures.**Executor
**```python
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)))
```
__main__
模块必须可以被工作者子进程导入。这意味着 ProcessPoolExecutor 不可以工作在交互式解释器中concurrent.futures.**ProcessPoolExecutor**
(max_workers=None, mp_context=None, initializer=None, initargs=())None
或未给出,它将默认为机器的处理器个数。 如果 max_workers 小于等于 0
,则将引发 ValueError。 在 Windows 上,max_workers 必须小于等于 61
,否则将引发 ValueError。 如果 max_workers 为 None
,则所选择的默认最多为 61
,即使存在更多处理器。None
或未给出,将使用默认的多进程上下文。BrokenProcessPool
。BrokenProcessPool
就会马上触发。 可预计的行为没有定义,但执行器上的操作或它的 future 对象会被冻结或死锁。```python
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.ProcessPoolExecutor() as executor:
for number, prime in zip(PRIMES, executor.map(is_prime, PRIMES)):
print('%d is prime: %s' % (number, prime))
if __name__ == '__main__':
```
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原创声明:本文系作者授权腾讯云开发者社区发表,未经许可,不得转载。
如有侵权,请联系 cloudcommunity@tencent.com 删除。