The asyncio module provides infrastructure for writing single-threaded concurrent code using coroutines, multiplexing I/O access over sockets and other resources, running network clients and servers, and other related primitives. Here is a more detailed list of the package contents:
- a pluggable event loop with various system-specific implementations;
- transport and protocol abstractions (similar to those in Twisted);
- concrete support for TCP, UDP, SSL, subprocess pipes, delayed calls, and others (some may be system-dependent);
- a Future class that mimics the one in the concurrent.futures module, but adapted for use with the event loop;
- coroutines and tasks based on
yield from(PEP 380), to help write concurrent code in a sequential fashion; - cancellation support for Futures and coroutines;
- synchronization primitives for use between coroutines in a single thread, mimicking those in the threading module;
- an interface for passing work off to a threadpool, for times when you absolutely, positively have to use a library that makes blocking I/O calls.
Note: The implementation of asyncio was previously called "Tulip".
Installation
To install asyncio, type:
pip install asyncio
asyncio requires Python 3.3 or later! The asyncio module is part of the Python standard library since Python 3.4.
asyncio is a free software distributed under the Apache license version 2.0.
Websites
- asyncio project at GitHub: source code, bug tracker
- asyncio documentation
- Mailing list: python-tulip Google Group
- IRC: join the
#asynciochannel on the Freenode network
Development
The actual code lives in the 'asyncio' subdirectory. Tests are in the 'tests' subdirectory.
To run tests, run:
tox
Or use the Makefile:
make test
To run coverage (coverage package is required):
make coverage
On Windows, things are a little more complicated. Assume P is your
Python binary (for example C:\Python33\python.exe).
You must first build the _overlapped.pyd extension and have it placed in the asyncio directory, as follows:
C:\> P setup.py build_ext --inplace
If this complains about vcvars.bat, you probably don't have the required version of Visual Studio installed. Compiling extensions for Python 3.3 requires Microsoft Visual C++ 2010 (MSVC 10.0) of any edition; you can download Visual Studio Express 2010 for free from http://www.visualstudio.com/downloads (scroll down to Visual C++ 2010 Express).
Once you have built the _overlapped.pyd extension successfully you can run the tests as follows:
C:\> P runtests.py
And coverage as follows:
C:\> P runtests.py --coverage