python-3.x – 如何使用asyncio和redis创建全局连接

2023年8月25日 445次阅读

我是
python 3的新手,来自gevent和2.7的asyncio ….

如何创建所有人都可以使用的全局连接？例如.我将进行1个过程,例如10个asyncio线程,但我不希望每个线程单独连接.为什么？..会有… 100个内核,每个内核有10个线程,并且不希望有多个连接到redis

import asyncio
import asyncio_redis

async def worker():
    while True:
        data = await connection.brpop(['queue'], timeout=0)
        print(data)
        res = blocking_code(data)
        await connection.set('test',res)

#Process raw data here and all code is blocking
def blocking_code(data):
    results = {}
    return results

if __name__ == '__main__':
    connection = asyncio_redis.Connection.create(host='127.0.0.1', port=6379, poolsize=2)
    loop = asyncio.get_event_loop()
    tasks = [asyncio.ensure_future(worker()), asyncio.ensure_future(worker())]
    loop.run_until_complete(asyncio.gather(*tasks))
    connection.close()


    Traceback (most recent call last):
      File "/Users//worker.py", line 14, in <module>
        loop.run_until_complete(example())
      File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/asyncio/base_events.py", line 466, in run_until_complete
        return future.result()
      File "/Users//worker.py", line 7, in example
        data = yield from connection.brpop(['queue'], timeout=0)
    AttributeError: 'generator' object has no attribute 'brpop'

所以在上面我有两个任务,但我只想要1个redis连接

最佳答案

10 asyncio threads

以防万一 – asyncio coroutines在一个线程中运行.通过在I / O操作时在协同程序之间切换来实现并发.

为什么你的代码不起作用？

asyncio_redis.Connection.create – 是一个协程,您应该使用yield from来等待此操作以从中获取结果：

connection = yield from asyncio_redis.Connection.create(host='127.0.0.1', port=6379)

如何创建全局连接

如果您只有一个连接,那么使用asyncio可能无法获益.并发请求可能需要可以使用的连接池. asyncio_redis has简单的方法,例如：

import asyncio
import asyncio_redis


@asyncio.coroutine
def main():
    connection = yield from asyncio_redis.Pool.create(host='127.0.0.1', port=6379, poolsize=10)
    try:
        # 3 requests running concurrently in single thread using connections from pool: 
        yield from asyncio.gather(
            connection.brpop(['queue:pixel'], timeout=0),
            connection.brpop(['queue:pixel'], timeout=0),
            connection.brpop(['queue:pixel'], timeout=0),
        )
    finally:
        connection.close()



if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    loop.run_until_complete(main())
    loop.close()

Python 3.5

如果您正在使用Python 3.5,请考虑使用newer syntax来定义和等待协同程序.

UPD：

阻止代码(例如,需要很多CPU时间的代码)不能直接在协程内部使用：它会冻结你的事件循环,你将无法获得asyncio的好处.它与连接数无关.

您可以使用run_in_executor在单独的进程中运行此代码,而不会阻塞事件循环：

from concurrent.futures import ProcessPoolExecutor


executor = ProcessPoolExecutor(max_workers=10)  # use number of cores here


async def worker():
    while True:
        data = await connection.brpop(['queue'], timeout=0)
        print(data)

        # await blocking_code from separate process:
        loop = asyncio.get_event_loop()
        result = await loop.run_in_executor(executor, blocking_code, data)
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