Crash when mlab render target is offscreen

[csaluski]

We have a data visualization program that renders plots to an offscreen target for later viewing. We were previously affected by #1325, but the recommendation to try building from master in the thread allowed us to build. However, we now experience a crash every time we try to initialize an off screen rendering target.

We run in Docker using xvfb to provide the render target.

Minimal reproduction:

from xvfbwrapper import Xvfb
vdisplay = Xvfb(width=1920, height=1080)
vdisplay.start()

from mayavi import mlab
mlab.options.offscreen = True

import faulthandler
faulthandler.enable()

print(f'[DEBUG] mlab call...', flush=True)
fig = mlab.figure(size=(1200, 974))
print(f'[DEBUG] mlab call succeeded.', flush=True)

vdisplay.stop()

And an environment that causes the crash, tested on Python 3.9 and 3.10, both have the same error.

FROM python:3.10 AS python_packages
# install packages to setup for processing
RUN apt update && apt install libgl1 xvfb -y
RUN pip install traits==6.4.3
RUN pip install traitsui==8.0.0
RUN pip install vtk==9.4.1
RUN pip install xvfbwrapper==0.2.9
RUN pip install https://github.com/enthought/mayavi/zipball/master

WORKDIR /src
COPY mayavi_test.py mayavi_test.py
ENTRYPOINT [ "python3" , "/src/mayavi_test.py" ]

The traceback (from faulthandler) follows, showing that it's failing somewhere in the initialization process.

Attaching to mayavi-1
mayavi-1  | /usr/local/lib/python3.10/site-packages/traits/etsconfig/etsconfig.py:425: UserWarning: Environment variable "HOME" not set, setting home directory to /tmp
mayavi-1  |   warn(
mayavi-1  | [DEBUG] mlab call...
mayavi-1  | Fatal Python error: Segmentation fault
mayavi-1  | 
mayavi-1  | Current thread 0x00007475bc82db80 (most recent call first):
mayavi-1  |   File "tvtk_classes/render_window_interactor.py", line 894 in initialize
mayavi-1  |   File "/usr/local/lib/python3.10/site-packages/tvtk/pyface/tvtk_scene.py", line 787 in _create_control
mayavi-1  |   File "/usr/local/lib/python3.10/site-packages/tvtk/pyface/tvtk_scene.py", line 216 in __init__
mayavi-1  |   File "/usr/local/lib/python3.10/site-packages/tvtk/pyface/tvtk_scene.py", line 930 in __init__
mayavi-1  |   File "/usr/local/lib/python3.10/site-packages/mayavi/core/off_screen_engine.py", line 16 in off_screen_viewer_factory
mayavi-1  |   File "/usr/local/lib/python3.10/site-packages/mayavi/core/engine.py", line 452 in new_scene
mayavi-1  |   File "/usr/local/lib/python3.10/site-packages/apptools/scripting/recordable.py", line 48 in _wrapper
mayavi-1  |   File "/usr/local/lib/python3.10/site-packages/mayavi/tools/figure.py", line 68 in figure
mayavi-1  |   File "/src/mayavi_test.py", line 12 in <module>

And a GDB trace of what appears to be the C++ VTK code that's crashing.

#0  0x0000000000000000 in ?? ()
#1  0x000073b0cde83db8 in vtkEGLRenderWindow::SetDeviceAsDisplay(int) () from /usr/local/lib/python3.9/site-packages/vtkmodules/libvtkRenderingOpenGL2.so
#2  0x000073b0cde84cd0 in vtkEGLRenderWindow::ResizeWindow(int, int) () from /usr/local/lib/python3.9/site-packages/vtkmodules/libvtkRenderingOpenGL2.so
#3  0x000073b0cde84e5f in vtkEGLRenderWindow::WindowInitialize() () from /usr/local/lib/python3.9/site-packages/vtkmodules/libvtkRenderingOpenGL2.so
#4  0x000073b0cddcc05b in vtkOpenGLRenderWindow::Start() () from /usr/local/lib/python3.9/site-packages/vtkmodules/libvtkRenderingOpenGL2.so
#5  0x000073b0d1bb29f5 in vtkRenderWindow::Render() () from /usr/local/lib/python3.9/site-packages/vtkmodules/libvtkRenderingCore.so
#6  0x000073b0cddd1e5a in vtkOpenGLRenderWindow::Render() () from /usr/local/lib/python3.9/site-packages/vtkmodules/libvtkRenderingOpenGL2.so
#7  0x000073b0d1bb6414 in vtkRenderWindowInteractor::Initialize() () from /usr/local/lib/python3.9/site-packages/vtkmodules/libvtkRenderingCore.so
#8  0x000073b0cb7ce645 in PyvtkRenderWindowInteractor_Initialize(_object*, _object*) () from /usr/local/lib/python3.9/site-packages/vtkmodules/vtkRenderingCore.cpython-39-x86_64-linux-gnu.so
#9  0x000073b100930eb0 in cfunction_call (func=<built-in method Initialize of vtkmodules.vtkRenderingUI.vtkGenericRenderWindowInteractor object at remote 0x73b0c060cee0>, args=<optimized out>, kwargs=<optimized out>) at Objects/methodobject.c:552