I’ve recently been seeing the following warning when running openstack
commands locally:
$ openstack server list -n -f yaml
QSocketNotifier: Can only be used with threads started with QThread
...
This made no sense: OSC doesn’t use Qt so why am I seeing errors related to
this? I also was only seeing it on one host. What gives? Well it took me a
while but it turned out this wasn’t due to OSC or even one of its direct
dependencies: it was an indirect dependency, pyperclip. By exporting
PYTHONPROFILEIMPORTTIME=1, I was able to figure out what import caused the
error:
$ export PYTHONPROFILEIMPORTTIME=1
$ openstack server list -n -f yaml
import time: self [us] | cumulative | imported package
import time: 647 | 647 | _io
...
import time: 160 | 345 | osc_lib.command.commandmanager
import time: 280 | 280 | _compat_pickle
import time: 227 | 227 | _pickle
import time: 64 | 64 | org
import time: 16 | 79 | org.python
import time: 15 | 93 | org.python.core
import time: 650 | 1248 | pickle
import time: 523 | 1771 | logging.handlers
import time: 161 | 161 | wcwidth.table_wide
import time: 342 | 342 | wcwidth.table_zero
import time: 129 | 129 | wcwidth.unicode_versions
import time: 267 | 897 | wcwidth.wcwidth
import time: 199 | 1096 | wcwidth
import time: 12691 | 13786 | cmd2.ansi
import time: 113 | 113 | cmd2.constants
import time: 1116 | 1228 | cmd2.argparse_custom
import time: 183 | 183 | cmd2.exceptions
import time: 922 | 922 | cmd2.utils
import time: 235 | 1340 | cmd2.command_definition
import time: 955 | 955 | cmd2.table_creator
import time: 404 | 2698 | cmd2.argparse_completer
import time: 264 | 264 | cmd
import time: 328 | 328 | _sysconfigdata__linux_x86_64-linux-gnu
import time: 1251 | 1578 | pydoc
import time: 133 | 133 | codeop
import time: 181 | 314 | code
import time: 151 | 151 | attr._compat
import time: 102 | 102 | attr._config
import time: 181 | 181 | attr.exceptions
import time: 107 | 287 | attr.setters
import time: 2597 | 2985 | attr._make
import time: 180 | 3315 | attr.converters
import time: 132 | 132 | attr.filters
import time: 3697 | 3697 | attr.validators
import time: 161 | 161 | attr._cmp
import time: 139 | 139 | attr._funcs
import time: 573 | 573 | attr._version_info
import time: 142 | 142 | attr._next_gen
import time: 285 | 8439 | attr
import time: 264 | 264 | shlex
import time: 3435 | 3698 | cmd2.parsing
import time: 1509 | 13645 | cmd2.plugin
import time: 364 | 364 | _ctypes
import time: 186 | 186 | ctypes._endian
import time: 589 | 1138 | ctypes
import time: 306 | 1444 | pyperclip
import time: 76 | 76 | gtk
import time: 71 | 71 | qtpy
import time: 220 | 220 | PyQt5
import time: 54 | 54 | qtpy
import time: 17 | 71 | qtpy.QtWidgets
import time: 342 | 342 | PyQt5.sip
import time: 6530 | 6530 | PyQt5.QtCore
import time: 5953 | 5953 | PyQt5.QtGui
import time: 14655 | 27478 | PyQt5.QtWidgets
QSocketNotifier: Can only be used with threads started with QThread
...
As for why I wasn’t seeing this on other hosts: those other hosts didn’t have PyQT5 installed.
$ sudo dnf remove PyQt5
Dependencies resolved.
=====================================================================================================================================================================================================================
Package Architecture Version Repository Size
=====================================================================================================================================================================================================================
Removing:
python3-qt5 x86_64 5.15.6-3.fc36 @fedora 7.0 M
Removing dependent packages:
krop noarch 0.5.1-13.fc36 @fedora 6.5 k
Removing unused dependencies:
poppler-qt5 x86_64 22.01.0-3.fc36 @fedora 632 k
python-qt5-rpm-macros noarch 5.15.6-3.fc36 @fedora 143
python3-PyPDF2 noarch 1.26.0-19.fc36 @fedora 520 k
python3-krop noarch 0.5.1-13.fc36 @fedora 225 k
python3-poppler-qt5 x86_64 21.1.0-5.fc36 @fedora 562 k
python3-pyqt5-sip x86_64 12.9.0-3.fc36 @fedora 154 k
python3-qt5-base x86_64 5.15.6-3.fc36 @fedora 17 M
qt5-qtconnectivity x86_64 5.15.3-1.fc36 @fedora 1.4 M
Transaction Summary
=====================================================================================================================================================================================================================
Remove 10 Packages
Freed space: 28 M
Is this ok [y/N]: y
...
I’d installed krop at some point and it had dragged in various Python
dependencies as a result. The ultimate fix probably exists somewhere in
pyperclip (or even PyQt5) but uninstalling things was enough to get rid of this
annoying warning.
Hopefully Google finds this page in case anyone is similarly frustrated by this.