python如何在多线程中使用异步

本文介绍: 关于 python：Run timeEr ro r：线程’Th read-1’中没有当前事件循环，多线程和异步错误Attr i bu t eEr ro r: module ‘async io‘ ha s no attr i bu te ‘Win do wsSelect o rEven tLoopPol ic y‘

这是一个 异步 爬虫，上代码

    headers = {
        "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.99 Safari/537.36"}
    async def fetch(url, semaphore):
        async with semaphore:
            async with aiohttp.ClientSession() as session:
                try:
                    async with session.get(url, headers=headers, timeout=10) as response:
                        # proxies = {"http": "http://10.10.1.10:3128","https": "http://10.10.1.10:1080"}
                        # async with session.get(url, headers=headers, timeout=10,proxy=proxies) as response:#代理IP设置
                        return await response.text(), url
                except:
                    return """<html&gt;<head&gt;<title&gt;Error</title&gt;</head&gt;</html&gt;""", url
    async def main():
        urls=[]#网址自定义
        semaphore = asyncio.Semaphore(500)#设置默认并发数500，在windows中最大为512， Linux中限制为1024
        tasks = [fetch(url,semaphore) for url in urls]
        responses = await asyncio.gather(*tasks)
        for response in responses:
            print(response[0],response[1])#可以在这里处置返回的网址数据

    loop = asyncio.get_event_loop()
    loop.run_until_complete(main())

将其放进Th reading 线程的时候会报错

错误提示1：RuntimeError: The re is no current event loop in thread ‘Th read-1’.
使用网上的方法说是添加

asyncio.set_event_loop_policy(asyncio.WindowsProactorEventLoopPolicy())
loop = asyncio.new_event_loop()
asyncio.set_event_loop(loop)

https://www.code non g.com/48725890/

也会报错提示：AttributeError: module ‘asyncio‘ has no attribute ‘Windo wsSelectorEventLoopPol ic y‘ 。
可能是版本问题导致吧，使用的版本是python3.6.7版本。

解决方法

将调用代码

        loop = asyncio.get_event_loop()#获取线程事件
        loop.run_until_complete(main())#调用

替换如下：

        loop = asyncio.new_event_loop()#新建一个线程事件
        asyncio.set_event_loop(loop)#设置线程事件
        loop.run_until_complete(main())#调用

分析可能是由于直接调用线程事件和threading.Thread 冲突了

        t1=Reptile_Thread()
        t1.start()
        print("运行")

class Reptile_Thread(threading.Thread):
    """网站爬取线程"""
    def __init__(self,parent=None):
        super(Reptile_Thread, self).__init__(parent)
    def run(self):
    	    headers = {
        "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.99 Safari/537.36"}
    async def fetch(url, semaphore):
        async with semaphore:
            async with aiohttp.ClientSession() as session:
                try:
                    async with session.get(url, headers=headers, timeout=10) as response:
                        # proxies = {"http": "http://10.10.1.10:3128","https": "http://10.10.1.10:1080"}
                        # async with session.get(url, headers=headers, timeout=10,proxy=proxies) as response:#代理IP设置
                        return await response.text(), url
                except:
                    return """<html><head><title>Error</title></head></html>""", url
    async def main():
        urls=[]#网址自定义
        semaphore = asyncio.Semaphore(500)#设置默认并发数500，在windows中最大为512， Linux中限制为1024
        tasks = [fetch(url,semaphore) for url in urls]
        responses = await asyncio.gather(*tasks)
        for response in responses:
            print(response[0],response[1])#可以在这里处置返回的网址数据
    #使用一下方法可以解决该错误。
    loop = asyncio.new_event_loop()#新建一个线程事件
    asyncio.set_event_loop(loop)#设置线程事件
    loop.run_until_complete(main())#调用