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.
Runner	A context manager that simplifies multiple async function calls.
Task	Task object.
TaskGroup	A context manager that holds a group of tasks. Provides a convenient and reliable way to wait for all tasks in the group to finish.
create_task()	Start an asyncio Task, then returns it.
current_task()	Return the current Task.
all_tasks()	Return all tasks that are not yet finished for an event loop.
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.
timeout()	Run with a timeout. Useful in cases when wait_for is not suitable.
to_thread()	Asynchronously run a function in a separate OS thread.
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.
Barrier	A barrier object.

Examples

• Using asyncio.Event.

• Using asyncio.Barrier.

• See also the documentation of asyncio synchronization primitives.

Exceptions

asyncio.CancelledError	Raised when a Task is cancelled. See also Task.cancel().
asyncio.BrokenBarrierError	Raised when a Barrier is broken. See also Barrier.wait().

Examples

• Handling CancelledError to run code on cancellation request.

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