New submission from Gabriel Mesquita Cangussu:
The documentation of asyncio specifies that the methods connect_read_pipe and
connect_write_pipe are available on Windows with the ProactorEventLoop. The
documentation then says that those methods accept file-like objects on the pipe
parameter. However, the methods doesn't seem to work with stdio or any disk
file under Windows. The following example catches this problem:
import asyncio
import sys
class MyProtocol(asyncio.Protocol):
def connection_made(self, transport):
print('connection established')
def data_received(self, data):
print('received: {!r}'.format(data.decode()))
def connection_lost(self, exc):
print('lost connection')
if sys.platform.startswith('win32'):
loop = asyncio.ProactorEventLoop()
else:
loop = asyncio.SelectorEventLoop()
coro = loop.connect_read_pipe(MyProtocol, sys.stdin)
loop.run_until_complete(coro)
loop.run_forever()
loop.close()
This code when executed on Ubuntu have the desired behavior, but under Windows
10 it gives OSError: [WinError 6] The handle is invalid. The complete output is
this:
c:\Users\Gabriel\Documents\Python Scripts>python async_pipe.py
connection established
Fatal read error on pipe transport
protocol: <__main__.MyProtocol object at 0x000001970EB2FAC8>
transport: <_ProactorReadPipeTransport fd=0>
Traceback (most recent call last):
File "C:\Program Files\Python35\lib\asyncio\proactor_events.py", line 195, in
_loop_reading
self._read_fut = self._loop._proactor.recv(self._sock, 4096)
File "C:\Program Files\Python35\lib\asyncio\windows_events.py", line 425, in
recv
self._register_with_iocp(conn)
File "C:\Program Files\Python35\lib\asyncio\windows_events.py", line 606, in
_register_with_iocp
_overlapped.CreateIoCompletionPort(obj.fileno(), self._iocp, 0, 0)
OSError: [WinError 6] Identificador inválido
lost connection
I think that the documentation should state that there is no support for disk
files and stdio with the methods in question and also state what exactly they
support (an example would be nice). And, of course, better support for watching
file descriptors on Windows on future Python releases would be nice.
Thank you,
Gabriel
----------
components: Windows, asyncio
messages: 264043
nosy: Gabriel Mesquita Cangussu, gvanrossum, haypo, paul.moore, steve.dower,
tim.golden, yselivanov, zach.ware
priority: normal
severity: normal
status: open
title: ProactorEventLoop doesn't support stdin/stdout nor files with
connect_read_pipe/connect_write_pipe
type: behavior
versions: Python 3.5
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Python tracker <[email protected]>
<http://bugs.python.org/issue26832>
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