Author samh42
Recipients ned.deily, ronaldoussoren, samh42
Date 2021-07-10.11:02:26
SpamBayes Score -1.0
Marked as misclassified Yes
Message-id <>
The behaviour of select.poll() is inconsistent across MacOS versions, on MacOS Mojave (10.14.6) registering and polling the receiving channel of mp.Pipe(duplex=False) returns the event POLLOUT (ready to write to). This is verified by a colleagues setup.

Whereas on MacOS 11 the same scenario will not have poll() return that the receiving channel is ready for writing to (POLLOUT). 

import select
import multiprocessing as mp
recv_end, send_end = mp.Pipe(duplex=False)
poll = select.poll()

MacOS 10.14.6 Result: 
> [(3,4)]

MacOS 11.0.1 Result:
> []

I am assuming that the MacOS 11 behaviour is should be the expected behaviour, and that the recv connection from a Pipe should never return that it is writable.

This was tested with Python 3.9.4, and 3.7.6.
Date User Action Args
2021-07-10 11:02:27samh42setrecipients: + samh42, ronaldoussoren, ned.deily
2021-07-10 11:02:27samh42setmessageid: <>
2021-07-10 11:02:26samh42linkissue44597 messages
2021-07-10 11:02:26samh42create