asyncio module is designed to be portable,
but some platforms have subtle differences and limitations
due to the platforms’ underlying architecture and capabilities.
Changed in version 3.8: On Windows,
ProactorEventLoop is now the default event loop.
All event loops on Windows do not support the following methods:
loop.create_unix_server()are not supported. The
socket.AF_UNIXsocket family is specific to Unix.
loop.remove_signal_handler()are not supported.
SelectorEventLoop has the following limitations:
SelectSelectoris used to wait on socket events: it supports sockets and is limited to 512 sockets.
loop.add_writer()only accept socket handles (e.g. pipe file descriptors are not supported).
loop.connect_write_pipe()methods are not implemented.
loop.subprocess_shell()methods are not implemented.
ProactorEventLoop has the following limitations:
The resolution of the monotonic clock on Windows is usually around 15.6 msec. The best resolution is 0.5 msec. The resolution depends on the hardware (availability of HPET) and on the Windows configuration.
Modern macOS versions are fully supported.
macOS <= 10.8
On macOS 10.6, 10.7 and 10.8, the default event loop
selectors.KqueueSelector, which does not support
character devices on these versions. The
can be manually configured to use
PollSelector to support character devices on
these older versions of macOS. Example:
import asyncio import selectors selector = selectors.SelectSelector() loop = asyncio.SelectorEventLoop(selector) asyncio.set_event_loop(loop)