Use AIOHTTP to build a high -performance web reptile

Use AIOHTTP to build a high -performance web reptile High performance is very important in the task of crawling on the Internet.AIOHTTP is a Python library based on asynchronous I/O, which provides a tool for building high -performance network applications.This article will introduce how to use the AIOHTTP library to build a high -performance web reptile, and provide related programming code and configuration description. 1. Install AIOHTTP library Before starting, we first need to install the AIOHTTP library.You can use the following command to install in the terminal: shell pip install aiohttp 2. Asynchronous request Because the asynchronous I/O is used, multiple network requests can be sent at the same time without waiting for the response of each request.This can greatly improve the performance of reptiles.The following is an example of a simple asynchronous request: python import aiohttp import asyncio async def fetch(session, url): async with session.get(url) as response: return await response.text() async def main(): async with aiohttp.ClientSession() as session: html = await fetch(session, 'http://example.com') print(html) loop = asyncio.get_event_loop() loop.run_until_complete(main()) In this example, we use the `ClientSession` class in the AIOHTTP library to create a session object.The `fetch` function is used to initiate a Get request and return the response text content.In the `Main` function, we created an asynchronous context manager, and called the` fetch` function to get the content of the `http://eXample.com` webpage. 3. concurrent request A high -performance web reptile usually needs to process multiple requests at the same time.To implement concurrency requests, you can use the `Gather` function provided by Python's` Asyncio` library.The following is an example of a complicated request: python import aiohttp import asyncio async def fetch(session, url): async with session.get(url) as response: return await response.text() async def main(): async with aiohttp.ClientSession() as session: urls = ['http://example.com', 'http://example.org', 'http://example.net'] tasks = [] for url in urls: task = asyncio.ensure_future(fetch(session, url)) tasks.append(task) responses = await asyncio.gather(*tasks) for response in responses: print(response) loop = asyncio.get_event_loop() loop.run_until_complete(main()) In this example, we created a URL list and used the `asyncio.ensure_future` function to encapsulate each request into asynchronous task (TASK).Then, use the `asyncio.gather` function to run these asynchronous tasks at the same time and save the results in the` Responses` list. 4. Configuration reptile To build a strong web crawler with AIOHTTP, you need to consider some configurations.Here are some common configuration options: -Set the request header: You can use the `headers` parameter to set the request header information, such as the User-Agent field. -Out timeout setting: You can use the `Timeout` parameter to set the timeout to prevent the request from not responding for a long time. -Egent settings: If you need to use the proxy server for request, you can use the `Proxy` parameter to set the proxy. -Cookie Management: You can use `Aiohttp.cookiejar ()` to manage the cookies in the request. -A connection pool management: You can use the `Aiohttp.tcpconnector ()` class to manage the connection with the target server. For example, the following is a crawler that configures the request head and timeout time: python import aiohttp import asyncio async def fetch(session, url): async with session.get(url) as response: return await response.text() async def main(): headers = {'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.3'} timeout = aiohttp.clientTimeout (Total = 10) # Set time timeout is 10 seconds Connector = aiohttp.tcpconnector (limit = 10) # Set the size of the connection pool to 10 async with aiohttp.ClientSession(headers=headers, timeout=timeout, connector=connector) as session: html = await fetch(session, 'http://example.com') print(html) loop = asyncio.get_event_loop() loop.run_until_complete(main()) In this example, we created a custom request head `headers`, and set up the total overtime time of 10 seconds with` AIOHTTP.ClientTimeout`.At the same time, we also use `Aiohttp.tcpconnector` to set the size of the connection pool to 10. Through the above description and code example, we can use the Aiohttp library to build a high -performance web reptile.Using asynchronous requests and concurrent requests can greatly improve the performance of reptiles.In addition, through configuring the appropriate request head, timeout time, agent, cookie management and connection pool management, it can meet more actual needs.