在线程中,我们有一个叫做“线程上下文”的东西,我们可以在其中保存一些数据(状态)以供在特殊线程中访问。在 asyncio 中,我需要在当前执行路径中保存一些状态,以便所有后续协程都可以访问它。解决办法是什么? 注意:我知道每个协程函数都是为 asyncio 中的执行路径实例化的,但由于某种原因我无法在函数属性中保存状态。 (虽然这个方法os反正不是很好)
最佳答案
从 Python 3.7 开始,您可以使用 contextvars.ContextVar .
在下面的示例中,我声明了 request_id 并在 some_outer_coroutine 中设置了值,然后在 some_inner_coroutine 中访问了它。
import asyncio
import contextvars
# declare context var
request_id = contextvars.ContextVar('Id of request.')
async def some_inner_coroutine():
# get value
print('Processed inner coroutine of request: {}'.format(request_id.get()))
async def some_outer_coroutine(req_id):
# set value
request_id.set(req_id)
await some_inner_coroutine()
# get value
print('Processed outer coroutine of request: {}'.format(request_id.get()))
async def main():
tasks = []
for req_id in range(1, 5):
tasks.append(asyncio.create_task(some_outer_coroutine(req_id)))
await asyncio.gather(*tasks)
if __name__ == '__main__':
asyncio.run(main())
输出:
Processed inner coroutine of request: 1
Processed outer coroutine of request: 1
Processed inner coroutine of request: 2
Processed outer coroutine of request: 2
Processed inner coroutine of request: 3
Processed outer coroutine of request: 3
Processed inner coroutine of request: 4
Processed outer coroutine of request: 4
关于Python 异步上下文,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/30596484/