在Google Colab运行Playwright遇事件循环错误，求可行解决方案

问题背景 #

在Google Colab中运行Playwright时，分别尝试同步API和异步API均遭遇事件循环相关错误：

1. 同步API报错情况 #

使用以下同步代码：

!pip install playwright
from playwright.sync_api import sync_playwright

with sync_playwright() as p:
    browser = p.firefox.launch(headless=True)
    page = browser.new_page()
    page.goto("https://www.google.com")

    page.wait_for_timeout(3000)
    browser.close()

触发报错：

ERROR:root:An unexpected error occurred while tokenizing input
The following traceback may be corrupted or invalid
The error message is: ('EOF in multi-line string', (1, 33))

---------------------------------------------------------------------------
Error                                     Traceback (most recent call last)
<ipython-input-29-bc0f59648c4a> in <module>()
      1 from playwright.sync_api import sync_playwright
      2 
----> 3 with sync_playwright() as p:
      4     browser = p.firefox.launch(headless=True)
      5     page = browser.new_page()

/usr/local/lib/python3.7/dist-packages/playwright/sync_api/_context_manager.py in __enter__(self)
     44             raise Error(
     45                 """It looks like you are using Playwright Sync API inside the asyncio loop.
---> 46 Please use the Async API instead."""
     47             )
     48 

Error: It looks like you are using Playwright Sync API inside the asyncio loop.
Please use the Async API instead.

2. 异步API报错情况 #

改用异步代码后：

import time
import asyncio
from playwright.async_api import async_playwright

async def main():
    async with async_playwright() as p:
        browser = await p.chromium.launch(headless=False)
        page = await browser.new_page(storage_state='auth.json')
        await page.goto('https://www.instagram.com/explore/tags/alanzoka/')
        time.sleep(6)
        html = await page.content()

        time.sleep(5)

        # await browser.close()


asyncio.run(main())

仍触发报错：

---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
<ipython-input-34-c582898e6ee9> in <module>()
     27 
     28 
---> 29 asyncio.run(main())

/usr/lib/python3.7/asyncio/runners.py in run(main, debug)
     32     if events._get_running_loop() is not None:
     33         raise RuntimeError(
---> 34             "asyncio.run() cannot be called from a running event loop")
     35 
     36     if not coroutines.iscoroutine(main):

RuntimeError: asyncio.run() cannot be called from a running event loop

解决方案 #

步骤1：安装Playwright及浏览器依赖 #

首先在Colab单元格中执行安装命令：

!pip install playwright
!playwright install

步骤2：正确使用异步API #

Colab运行环境默认处于一个活跃的asyncio事件循环中，因此不能用asyncio.run()启动新循环，直接await异步函数即可。同时需避免在异步代码中使用阻塞式的time.sleep()，改用Playwright内置的异步等待方法：

import asyncio
from playwright.async_api import async_playwright

async def main():
    async with async_playwright() as p:
        # Colab建议使用无头模式运行浏览器
        browser = await p.chromium.launch(headless=True)
        page = await browser.new_page()
        # 访问目标页面
        await page.goto("https://www.google.com")
        # 使用Playwright异步等待替代time.sleep
        await page.wait_for_timeout(3000)
        # 获取页面内容
        html_content = await page.content()
        # 打印部分内容验证
        print(html_content[:500])
        # 关闭浏览器
        await browser.close()

# 在Colab中直接await执行异步函数
await main()

关键注意事项 #

• 避免同步API：Colab环境默认运行在asyncio事件循环内，Playwright同步API不支持这种场景，必须使用异步API。
• 禁用time.sleep：异步代码中使用time.sleep()会阻塞整个事件循环，改用await page.wait_for_timeout(毫秒数)或await asyncio.sleep(秒数)。
• 无头模式：Colab无图形界面，建议始终启用headless=True运行浏览器，避免显示相关异常。
• 认证状态处理：如果需要加载storage_state='auth.json'，需确保该文件已上传至Colab环境，或先通过Playwright完成登录并保存状态。

内容的提问来源于stack exchange，提问作者Himanshu Poddar