High-level API Index — Python 3.8.0 documentation

# High-level API Index

This page lists all high-level async/await enabled asyncio APIs.

## Tasks

Utilities to run asyncio programs, create Tasks, and await on multiple things with timeouts.

`run()` | Create event loop, run a coroutine, close the loop.
`create_task()` | Start an asyncio Task.
`await` `sleep()` | Sleep for a number of seconds.
`await` `gather()` | Schedule and wait for things concurrently.
`await` `wait_for()` | Run with a timeout.
`await` `shield()` | Shield from cancellation.
`await` `wait()` | Monitor for completion.
`current_task()` | Return the current Task.
`all_tasks()` | Return all tasks for an event loop.
`Task` | Task object.
`run_coroutine_threadsafe()` | Schedule a coroutine from another OS thread.
`for in` `as_completed()` | Monitor for completion with a `for` loop.

Examples

- Using asyncio.gather() to run things in parallel.

- Using asyncio.wait_for() to enforce a timeout.

- Cancellation.

- Using asyncio.sleep().

- See also the main Tasks documentation page.

## Queues

Queues should be used to distribute work amongst multiple asyncio Tasks, implement connection pools, and pub/sub patterns.

`Queue` | A FIFO queue.
`PriorityQueue` | A priority queue.
`LifoQueue` | A LIFO queue.

Examples

- Using asyncio.Queue to distribute workload between several Tasks.

- See also the Queues documentation page.

## Subprocesses

Utilities to spawn subprocesses and run shell commands.

`await` `create_subprocess_exec()` | Create a subprocess.
`await` `create_subprocess_shell()` | Run a shell command.

Examples

- Executing a shell command.

- See also the subprocess APIs documentation.

## Streams

High-level APIs to work with network IO.

`await` `open_connection()` | Establish a TCP connection.
`await` `open_unix_connection()` | Establish a Unix socket connection.
`await` `start_server()` | Start a TCP server.
`await` `start_unix_server()` | Start a Unix socket server.
`StreamReader` | High-level async/await object to receive network data.
`StreamWriter` | High-level async/await object to send network data.

Examples

- Example TCP client.

- See also the streams APIs documentation.

## Synchronization

Threading-like synchronization primitives that can be used in Tasks.

`Lock` | A mutex lock.
`Event` | An event object.
`Condition` | A condition object.
`Semaphore` | A semaphore.
`BoundedSemaphore` | A bounded semaphore.

Examples

- Using asyncio.Event.

- See also the documentation of asyncio synchronization primitives.

## Exceptions

`asyncio.TimeoutError` | Raised on timeout by functions like `wait_for()`. Keep in mind that `asyncio.TimeoutError` is unrelated to the built-in `TimeoutError` exception.
`asyncio.CancelledError` | Raised when a Task is cancelled. See also `Task.cancel()`.

Examples

- Handling CancelledError to run code on cancellation request.

- See also the full list of asyncio-specific exceptions.