asyncer

library0.0.18pypypi✓ verified 26d ago

Asyncer is a small Python library built on top of AnyIO, focused on improving developer experience when working with `async` and `await` and mixing async with regular blocking code. It provides utility functions like `asyncify` and `syncify` to bridge asynchronous and synchronous code more conveniently, offering better editor support and type checking. It is actively maintained, with frequent minor releases.

http-networking web-framework

pip install asyncer

github ↗package ↗docs ↗changelog ↗

INSTALL

IMPORT

SIG · ASYNCER

asyncer

http-networkingpythonv0.0.18

Install

2.0s avg

Import

251ms

Disk

18MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v0.0.18 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.95 runs

installs and imports cleanly · install 0.0s · import 0.258s · 20.1MB

glibc

py 3.10–3.95 runs

installs and imports cleanly · install 2.0s · import 0.244s · 21MB

18MB installed

● package 18MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

asyncify

✓ from asyncer import asyncify

Used to call synchronous (blocking) functions from an asynchronous context without blocking the event loop.

syncify

✓ from asyncer import syncify

Used to call asynchronous functions from a synchronous context.

This example demonstrates how to use `asyncer.asyncify` to call a regular blocking function (`blocking_function`) from within an asynchronous context (`main`). `asyncify` ensures the blocking operation runs in a worker thread, preventing it from blocking the main event loop. The `anyio.run(main)` call starts the AnyIO event loop to execute the asynchronous `main` function.

import anyio from asyncer import asyncify import time def blocking_function(name: str) -> str: """A blocking function that simulates work.""" time.sleep(0.1) # Simulate I/O or CPU-bound work return f"Hello from blocking func, {name}!" async def main(): print("Starting async main function.") # Run a blocking function in a worker thread using asyncify message = await asyncify(blocking_function)(name="World") print(message) print("Finished async main function.") if __name__ == "__main__": anyio.run(main)

Debug

Known issues

breakingAsyncer dropped support for Python 3.9 in version 0.0.15. Projects requiring Python 3.9 or older must use an earlier Asyncer version.

fix

Upgrade to Python 3.10 or higher, or pin Asyncer to `<0.0.15`.

affects: >=0.0.15

breakingAsyncer dropped support for Python 3.8 in version 0.0.12. Projects requiring Python 3.8 or older must use an earlier Asyncer version.

fix

Upgrade to Python 3.9 or higher (preferably 3.10+), or pin Asyncer to `<0.0.12`.

affects: >=0.0.12

deprecatedThe `cancellable` argument for `asyncify()` was refactored and is now `abandon_on_cancel`. Using `cancellable=True` might not have the intended effect or could lead to future breakage.

fix

Replace `asyncify(..., cancellable=True)` with `asyncify(..., abandon_on_cancel=True)`. Refer to AnyIO documentation for precise behavior of `abandon_on_cancel`.

affects: >=0.0.8

gotchaAsyncer functions, particularly `syncify`, expect to be called either from an existing asynchronous event loop (e.g., within an `async` function running via `anyio.run()` or `asyncio.run()`) or from a worker thread initiated by `asyncify`. Calling `syncify()` directly in a purely synchronous top-level context may implicitly start a new event loop or raise an error if `raise_sync_error` is not set to `False`.

fix

Ensure `asyncer` functions are used within an appropriate asynchronous context (e.g., `anyio.run()`) or explicitly handle synchronous execution with `syncify(..., raise_sync_error=False)`.

affects: All

gotchaThe Asyncer documentation recommends pinning the exact version of the library due to its small size and potential for future changes, and always having tests for your project.

fix

Pin the Asyncer version in your `requirements.txt` or `pyproject.toml` (e.g., `asyncer==0.0.17`) and maintain comprehensive tests to ensure compatibility when upgrading.

affects: All

Errors

Common errors & fixes

ModuleNotFoundError: No module named 'asyncer'

The 'asyncer' library is not installed in the Python environment.

fix

Install the 'asyncer' library using pip: 'pip install asyncer'.

SyntaxError: invalid syntax

Using 'async' as an identifier conflicts with its reserved keyword status in Python.

fix

Rename the variable or module named 'async' to avoid using reserved keywords.

RuntimeWarning: coroutine 'sender' was never awaited

A coroutine was defined but not awaited, leading to it not being executed.

fix

Ensure that all coroutines are awaited using 'await' or run with an event loop.

RuntimeError: Event loop is closed

Attempting to perform an operation after the event loop has been closed.

fix

Ensure the event loop is open before performing asynchronous operations.

AttributeError: module 'asyncio' has no attribute 'StreamReader'

Attempting to access a non-existent attribute in the 'asyncio' module.

fix

Verify the correct usage and attributes of the 'asyncio' module as per the official documentation.

Upgrade

Version history

0.0.18latest on PyPI · released Jun 25, 2026

Audit

Dependencies

anyiorequiredCore asynchronous backend library that Asyncer is built upon for concurrent execution.

sniffiorequiredUsed for detecting the current asynchronous backend in use (e.g., asyncio, Trio).

typing_extensionsoptionalProvides backported typing features for older Python versions. Required for Python < 3.15.

Agent activity

21 hits · last 30 days

node

Amazon

OpenAI (training)

Resources

githubhttps://github.com/fastapi/asyncer ↗

packagehttps://pypi.org/project/asyncer/ ↗

docshttps://asyncer.tiangolo.com ↗

changeloghttps://asyncer.tiangolo.com/release-notes/ ↗