异步非阻塞

Posted 2020-10-27 老王的农场

【异步】：回调

　　　　　　非组塞，完成后某个任务后，自动执行一个这个函数，回调告知结果。

【非阻塞】：不等，某一个socket，先链接，发送数据，再接收数据一气呵成，不等。

                   阻塞：client = socket（）；client.connet(ip,端口)

　　　　　　  非阻塞：client = socket（）；client.setblocking(False)；client.connet(ip,端口)。

　　　　　　　　　　链接，发送数据，接收数据。有数据拿数据，没数据直接报错。

 

很多模块支持异步非阻塞

 1 import asyncio  #不常用，原理
 2 
 3 
 4 @asyncio.coroutine
 5 def func1():
 6     print(\'before...func1......\')
 7     yield from asyncio.sleep(5)
 8     print(\'end...func1......\')
 9 
10 
11 tasks = [func1(), func1()]
12 
13 loop = asyncio.get_event_loop()
14 loop.run_until_complete(asyncio.gather(*tasks))
15 loop.close()

1.asyncio示例1

import asyncio


@asyncio.coroutine
def fetch_async(host, url=\'/\'):
    print(host, url)
    reader, writer = yield from asyncio.open_connection(host, 80)

    request_header_content = """GET %s HTTP/1.0\\r\\nHost: %s\\r\\n\\r\\n""" % (url, host,)
    request_header_content = bytes(request_header_content, encoding=\'utf-8\')

    writer.write(request_header_content)
    yield from writer.drain()
    text = yield from reader.read()
    print(host, url, text)
    writer.close()

tasks = [
    fetch_async(\'www.cnblogs.com\', \'/catherine007/\'),
    fetch_async(\'dig.chouti.com\', \'/pic/show?nid=4073644713430508&lid=10273091\')
]

loop = asyncio.get_event_loop()
results = loop.run_until_complete(asyncio.gather(*tasks))
loop.close()

1.asyncio示例2

1.asyncio示例2

import aiohttp
import asyncio


@asyncio.coroutine
def fetch_async(url):
    print(url)
    response = yield from aiohttp.request(\'GET\', url)
    # data = yield from response.read()
    # print(url, data)
    print(url, response)
    response.close()


tasks = [fetch_async(\'http://www.google.com/\'), fetch_async(\'http://www.chouti.com/\')]

event_loop = asyncio.get_event_loop()
results = event_loop.run_until_complete(asyncio.gather(*tasks))
event_loop.close()

2.asyncio + aiohttp

2.asyncio + aiohttp

import asyncio
import requests


@asyncio.coroutine
def fetch_async(func, *args):
    loop = asyncio.get_event_loop()
    future = loop.run_in_executor(None, func, *args)
    response = yield from future
    print(response.url, response.content)


tasks = [
    fetch_async(requests.get, \'http://www.cnblogs.com/\'),
    fetch_async(requests.get, \'http://dig.chouti.com/pic/show?nid=4073644713430508&lid=10273091\')
]

loop = asyncio.get_event_loop()
results = loop.run_until_complete(asyncio.gather(*tasks))
loop.close()

3.asyncio + requests

3.asyncio + requests

 gevent --Gevent依赖libevent和greenlet,需要分别安装.

　　　　　　（greenlet,libevent真正实现协程的模块）

              　　greenlet 1，不智能，遇到io阻塞请求不能自动切换，

　　　　　　　　　　　2，跟异步非阻塞没有任何关系

协程和异步非阻塞的区别？

没有任何关系，协程来回完成代码的切换，单纯没有意义，人为给的这个概念。

 gevent和greenlet结合起来，能完成一个异步非阻塞的模块功能。

import gevent

monkey.patch_all()

#将socket 替换成setblocking(False)

import gevent

import requests
from gevent import monkey

monkey.patch_all()


def fetch_async(method, url, req_kwargs):
    print(method, url, req_kwargs)
    response = requests.request(method=method, url=url, **req_kwargs)
    print(response.url, response.content)

# ##### 发送请求 #####
gevent.joinall([
    gevent.spawn(fetch_async, method=\'get\', url=\'https://www.python.org/\', req_kwargs={}),
    gevent.spawn(fetch_async, method=\'get\', url=\'https://www.yahoo.com/\', req_kwargs={}),
    gevent.spawn(fetch_async, method=\'get\', url=\'https://github.com/\', req_kwargs={}),
])

# ##### 发送请求（协程池控制最大协程数量） #####
# from gevent.pool import Pool
# pool = Pool(None)
# gevent.joinall([
#     pool.spawn(fetch_async, method=\'get\', url=\'https://www.python.org/\', req_kwargs={}),
#     pool.spawn(fetch_async, method=\'get\', url=\'https://www.yahoo.com/\', req_kwargs={}),
#     pool.spawn(fetch_async, method=\'get\', url=\'https://www.github.com/\', req_kwargs={}),
# ])

4.gevent + requests

4.gevent + requests

import grequests


request_list = [
    grequests.get(\'http://httpbin.org/delay/1\', timeout=0.001),
    grequests.get(\'http://fakedomain/\'),
    grequests.get(\'http://httpbin.org/status/500\')
]


# ##### 执行并获取响应列表 #####
# response_list = grequests.map(request_list)
# print(response_list)


# ##### 执行并获取响应列表（处理异常） #####
# def exception_handler(request, exception):
# print(request,exception)
#     print("Request failed")

# response_list = grequests.map(request_list, exception_handler=exception_handler)
# print(response_list)

5.grequests

5.grequests

from twisted.web.client import getPage, defer
from twisted.internet import reactor


def all_done(arg):
    reactor.stop()


def callback(contents):
    print(contents)


deferred_list = []

url_list = [\'http://www.bing.com\', \'http://www.baidu.com\', ]
for url in url_list:
    deferred = getPage(bytes(url, encoding=\'utf8\'))
    deferred.addCallback(callback)
    deferred_list.append(deferred)

dlist = defer.DeferredList(deferred_list)
dlist.addBoth(all_done)

reactor.run()

6.Twisted示例

6.Twisted示例

from tornado.httpclient import AsyncHTTPClient
from tornado.httpclient import HTTPRequest
from tornado import ioloop


def handle_response(response):
    """
    处理返回值内容（需要维护计数器，来停止IO循环），调用 ioloop.IOLoop.current().stop()
    :param response: 
    :return: 
    """
    if response.error:
        print("Error:", response.error)
    else:
        print(response.body)


def func():
    url_list = [
        \'http://www.baidu.com\',
        \'http://www.bing.com\',
    ]
    for url in url_list:
        print(url)
        http_client = AsyncHTTPClient()
        http_client.fetch(HTTPRequest(url), handle_response)


ioloop.IOLoop.current().add_callback(func)
ioloop.IOLoop.current().start()

7.Tornado

7.Tornado

from twisted.internet import reactor
from twisted.web.client import getPage
import urllib.parse


def one_done(arg):
    print(arg)
    reactor.stop()

post_data = urllib.parse.urlencode({\'check_data\': \'adf\'})
post_data = bytes(post_data, encoding=\'utf8\')
headers = {b\'Content-Type\': b\'application/x-www-form-urlencoded\'}
response = getPage(bytes(\'http://dig.chouti.com/login\', encoding=\'utf8\'),
                   method=bytes(\'POST\', encoding=\'utf8\'),
                   postdata=post_data,
                   cookies={},
                   headers=headers)
response.addBoth(one_done)

reactor.run()

Twisted更多

Twisted更多

 高性能相关

1，串行

2，线程，进程（可完成并发，但是资源消耗多）

3，异步非阻塞

　　-asycio

　　-gevent

　　-twisted

　　-tornado