Error using rqt with Xming 6.9.0.31 through PuTTY

Question

I am using Ubuntu 12.04 64-bit server in a Virtual Machine on my Win7 x86-64 laptop, I have been using text-only terminals with the VM all the time. I just installed ROS "hydro" base version on the VM using apt tools.

[u@ubuntu:~/ros/catkin_ws]$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 12.04.5 LTS
Release:        12.04
Codename:       precise

By using Xming 6.9.0.31 X server on my Win7 host, I can use "turtlesim" app correctly and the turtle can be moved using keyboard app or rostopic commands.

But error occurs when I tried to use the "rqt" tool:

[u@ubuntu:~/ros/catkin_ws]$ rosrun rqt_graph rqt_graph
[xcb] Unknown sequence number while processing queue
[xcb] Most likely this is a multi-threaded client and XInitThreads has not been called
[xcb] Aborting, sorry about that.
python: ../../src/xcb_io.c:274: poll_for_event: Assertion `!xcb_xlib_threads_sequence_lost' failed.
Aborted (core dumped)

BTW, I was using Putty to forward the access to the DISPLAY server on my Win7 host from within the Ubuntu VM and the rviz seems can show up a Window on my Win7 host w/o issues.

Does anyone have any hints here?

Regards, Yf

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Originally posted by yf on ROS Answers with karma: 1 on 2015-05-04

Post score: 0

Answer 1

This a quite a specific and unique setup you have there ;-) So I can't easily reproduce this, but searching for your error message brought me to the Qt.AA_X11InitThreads flag, that can be set before the QApplication is constructed: http://doc.qt.io/qt-4.8/qt.html

This flag is not being set currently by rqt, so you could try running rqt from source and edit the qt_gui/main.py file at about line 173: https://github.com/ros-visualization/qt_gui_core/blob/groovy-devel/qt_gui/src/qt_gui/main.py#L173

Directly before the line constructing the QApplication instance add a new line setting the mentioned attribute:

QApplication.setAttribute(Qt.AA_X11InitThreads, True)
app = QApplication(argv)

If that solves your problem, you can file a pull request with this change, so it gets tested on other setups and can hopefully be added to the code.

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Originally posted by Dorian Scholz with karma: 391 on 2015-06-24

This answer was ACCEPTED on the original site

Post score: 1

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Original comments

Comment by gvdhoorn on 2016-06-06:
Update: this was added to rqt in ros-visualization/qt_gui_core#62.