13.1 事件循環

asyncio
包含各種特定系統實現的模塊化事件循環
傳輸和協議抽象
對TCP、UDP、SSL、子進程、延時調用以及其他的具體支持
模仿futures模塊但適用于事件循環使用的Future類
基于 yield from 的協議和任務，可以讓你用順序的方式編寫并發代碼
必須使用一個將產生阻塞IO的調用時，有接口可以把這個事件轉移到線程池
模仿threading模塊中的同步原語、可以用在單線程內的協程之間

事件循環+回調(驅動生成器)+epoll(IO多路復用)
asyncio是python用于解決異步io編程的一整套解決方案
tornado、gevent、twisted(scrapy， django channels)
torando(實現web服務器)， django+flask(uwsgi, gunicorn+nginx)
tornado可以直接部署， nginx+tornado

import asyncio import time # 不再這使用同步阻塞的timeasync def get_html(url):print("start get url")await asyncio.sleep(2)# time.sleep(2) 不要這樣寫print("end get url")if __name__ == "__main__":start_time = time.time()loop = asyncio.get_event_loop()tasks = [get_html("http://www.imooc.com") for i in range(10)]loop.run_until_complete(asyncio.wait(tasks))print(time.time() - start_time)""" start get url start get url start get url start get url start get url start get url start get url start get url start get url start get url end get url end get url end get url end get url end get url end get url end get url end get url end get url end get url 2.001918077468872 """ # 使用asyncio import asyncio import timefrom functools import partial # 偏函數async def get_html(url):print("start get url")await asyncio.sleep(2)return "lewen"def callback(url, future):print(url)print("send callback email to lewen")if __name__ == "__main__":start_time = time.time()loop = asyncio.get_event_loop() # 事件循環# task = asyncio.ensure_future(get_html("http://www.imooc.com")) # 任務的兩種不同寫法task = loop.create_task(get_html("http://www.imooc.com"))task.add_done_callback(partial(callback, "http://www.imooc.com"))loop.run_until_complete(task)print(task.result())""" start get url http://www.imooc.com send callback email to lewen lewen """ # 獲取協程的返回值 import asyncio import timeasync def get_html(url):print("start get url")await asyncio.sleep(2)print("end get url")if __name__ == "__main__":start_time = time.time()loop = asyncio.get_event_loop()tasks = [get_html("http://www.imooc.com") for i in range(10)]# loop.run_until_complete(asyncio.gather(*tasks))loop.run_until_complete(asyncio.wait(tasks))# print(time.time()-start_time)# gather和wait的區別# gather更加高層 high-level 分組group1 = [get_html("http://projectsedu.com") for i in range(2)]group2 = [get_html("http://www.imooc.com") for i in range(2)]group1 = asyncio.gather(*group1)group2 = asyncio.gather(*group2)# group2.cancel() #取消loop.run_until_complete(asyncio.gather(group1, group2))print(time.time() - start_time) # wait 和 gather

13.2 協程嵌套

13.3 call_soon、call_later、call_at、call_soon_threadsafe

import asynciodef callback(sleep_times, loop):print("success time {}".format(loop.time()))def stoploop(loop):loop.stop()# call_later, call_at if __name__ == "__main__":loop = asyncio.get_event_loop()# 馬上執行隊列里面的task# loop.call_soon(callback, 4, loop)# loop.call_soon(stoploop, loop)# call_later() 等待多少秒后執行# loop.call_later(2, callback, 2, loop)# loop.call_later(1, callback, 1, loop)# loop.call_later(3, callback, 3, loop)# call_at() 在某一時刻執行now = loop.time()loop.call_at(now+2, callback, 2, loop)loop.call_at(now+1, callback, 1, loop)loop.call_at(now+3, callback, 3, loop)loop.run_forever()# loop.call_soon_threadsafe() view

13.4 ThreadPoolExecutor+asyncio

# 使用多線程：在協程中集成阻塞io # 數據庫等阻塞式IO import asyncio from concurrent.futures import ThreadPoolExecutor import socket from urllib.parse import urlparsedef get_url(url):# 通過socket請求htmlurl = urlparse(url)host = url.netlocpath = url.pathif path == "":path = "/"# 建立socket連接client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)# client.setblocking(False)client.connect((host, 80)) # 阻塞不會消耗cpu# 不停的詢問連接是否建立好， 需要while循環不停的去檢查狀態# 做計算任務或者再次發起其他的連接請求client.send("GET {} HTTP/1.1\r\nHost:{}\r\nConnection:close\r\n\r\n".format(path, host).encode("utf8"))data = b""while True:d = client.recv(1024)if d:data += delse:breakdata = data.decode("utf8")html_data = data.split("\r\n\r\n")[1]print(html_data)client.close()if __name__ == "__main__":import timestart_time = time.time()loop = asyncio.get_event_loop()executor = ThreadPoolExecutor(3) # 線程池tasks = []for url in range(20):url = "http://www.baidu.com/s?wd={}/".format(url)task = loop.run_in_executor(executor, get_url, url) # 將阻塞的放到執行器里面tasks.append(task)loop.run_until_complete(asyncio.wait(tasks))print("last time:{}".format(time.time() - start_time))# 將線程池直接應用到協程里面

13.5 asyncio模擬http請求

# coding=utf-8 # asyncio 沒有提供http協議的接口 aiohttp import asyncio from urllib.parse import urlparseasync def get_url(url):# 通過socket請求htmlurl = urlparse(url)host = url.netlocpath = url.pathif path == "":path = "/"# 建立socket連接reader, writer = await asyncio.open_connection(host, 80)writer.write("GET {} HTTP/1.1\r\nHost:{}\r\nConnection:close\r\n\r\n".format(path, host).encode("utf8"))all_lines = []async for raw_line in reader:data = raw_line.decode("utf8")all_lines.append(data)html = "\n".join(all_lines)return htmlasync def main():tasks = []for url in range(20):url = "http://www.baidu.com/s?wd={}/".format(url)tasks.append(asyncio.ensure_future(get_url(url)))for task in asyncio.as_completed(tasks):result = await taskprint(result)if __name__ == "__main__":import timestart_time = time.time()loop = asyncio.get_event_loop()loop.run_until_complete(main())print('last time:{}'.format(time.time() - start_time))

13.6 future和task

future 結果容器

task 是 future 的子類，協程和future之間的橋梁，啟動協程

13.7 asyncio同步和通信

total = 0async def add():# 1，dosomething1# 2.io操作# 1.dosomething3global totalfor i in range(100000):total += 1async def desc():global totalfor i in range(100000):total -= 1if __name__ == "__main__":import asynciotasks = [add(), desc()]loop = asyncio.get_event_loop()loop.run_until_complete(asyncio.wait(tasks))print(total) # 不需要鎖的情況

13.8 aiohttp實現高并發爬蟲

與50位技術專家面對面20年技術見證，附贈技術全景圖

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