# Python Asyncio Module

`asyncio` is a library to write concurrent code using the `async`/`await` syntax. It is used as a foundation for multiple Python asynchronous frameworks that provide high-performance network and web-servers, database connection libraries, distributed task queues, etc.

## Importing the Module

```python
import asyncio
```

## Basic Usage

### Defining a Coroutine

A coroutine is declared with `async def`.

```python
import asyncio

async def main():
    print('Hello')
    await asyncio.sleep(1)
    print('...World!')

# Running the top-level entry point
# asyncio.run(main())
```

## Running Concurrent Tasks

Use `asyncio.gather()` to run multiple coroutines concurrently.

```python
import asyncio
import time

async def say_after(delay, what):
    await asyncio.sleep(delay)
    print(what)

async def main():
    print(f"started at {time.strftime('%X')}")

    await asyncio.gather(
        say_after(1, 'hello'),
        say_after(2, 'world')
    )

    print(f"finished at {time.strftime('%X')}")

if __name__ == "__main__":
    asyncio.run(main())
```

## Timeouts

You can set a timeout for a coroutine using `asyncio.wait_for()`.

```python
try:
    await asyncio.wait_for(eternity(), timeout=1.0)
except asyncio.TimeoutError:
    print('timeout!')
```

[[programming/python/python]]