ToolPalette._layout_widgets() appears to recurse, causing a stack overflow #27
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Original comment by Chris Billington (Bitbucket: cbillington, GitHub: chrisjbillington).
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Original comment by Philip Starkey (Bitbucket: philipstarkey, GitHub: philipstarkey). This is a bit of a shot in the dark, but I suspect that there is a bug when calculating how many items fit in a row. This is likely due to incorrectly accounting for padding/borders/similar. I think such a error could lead to the behaviour you saw (but it's a a while since I touched that code) Plausibly this issue could cause segfaults on some versions of Qt as Qt often doesn’t like doing things really fast (some of which may be fixed in later versions of Qt) |
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Original comment by Chris Billington (Bitbucket: cbillington, GitHub: chrisjbillington). I suspect you're right, that the calculation could be a little bit off. But it would be good if the code wasn't sensitive to relatively minor errors or to changing padding values, so fixing the calculation itself might not be the best solution, unless it's totally bomb-proof and looks up all the padding values at run-time with no hard-coded values. There are also things that can happen where a widget says it is one size, and on that basis a container widget decides it should show a scrollbar or something, then the child widget is updated with the new size of the container (minus the scrollbar width), it declares itself to be smaller, then the parent widget decides it doesn't need a scrollbar after all, repeat. In this case something needs to break the cycle. We might be able to add a "with signals disconnected, update size" or similar to just stop recursion and keep the most recently calculated size. If that size if "good enough" then we'll be happy, even if there is some hysteresis in the number of buttons per row whilst resizing tabs. |
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I ran into this bug today and managed to work around it in a way that kept the data in the blacs settings file, which is lost when following the suggestion from the mailing list. I opened the blacs settings file in HDFView, then went to I'm sure |
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@zakv Can you reproduce it with your configuration if you set the value back to Also, Do the widgets on one of the visible tabs (at that window size) just require a scroll bar? I'm wondering if it's due to a relayout swapping between needing a scroll bar and not, and perhaps just making the scrollbar always visible would be a sufficient fix? |
Yep. I backed up that non-functional config file and was able to reproduce the bug by reverting to it. I also then edited it to set the window height to 1000, opened blacs (which worked), then closed blacs, then reset the window height back to 732 with HDFView, then blacs failed to open again.
Yep. I don't know a good way to set the height to 732 pixels given that I can't get blacs to open with that setting, but opening it with the height set to 1000, then adjusting it to be ~3/4 it's original height gives this: Also, not sure if this is relevant but the blacs window is partially off the left edge of the screen when I open it with that settings file. For reference, here is how it looks right after I open with with the height set to 1000: |
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For what it's worth I've been sent (from one of the other users having this issue) a config file that may be able to reproduce it - haven't looked at it yet, but will give it a shot at some point. Can send it to you if you want to look into this Phil. |
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I've run into this issue a few times in the last several months and I recently started learning a bit about Qt, so I decided to take another look at it. My hope was to just count the recursion depth and implement Chris's "with signals disconnected, update size" idea when it got too deep. Unfortunately it looks like my initial naïve implementation of that approach won't work. After uncommenting/adding some debugging print statements in
Before this I had thought
Given that, the only way I can think of to implement Chris's "with signals disconnected, update size" idea is to add custom events to the Qt event queue. Basically I should get a chance to try to implement that soon, though I haven't worked with the Qt event system before so it might take a decent amount of trial/error before I get something working. |
…vent() could trigger itself in an infinite resursion loop.
…vent() could trigger itself in an infinite resursion loop.
commit a79d0e4 Author: David Meyer <[email protected]> Date: Tue Nov 30 11:20:27 2021 -0500 Update setup.cfg in preparation for release. commit 811b43d Merge: b8726ad a3be0db Author: David Meyer <[email protected]> Date: Wed Nov 10 17:07:51 2021 -0500 Merge pull request #81 from chrisjbillington/py36-path-bug Fix bug on Python3.6 commit b8726ad Merge: d309a5f c4dd2a8 Author: David Meyer <[email protected]> Date: Wed Nov 10 17:06:47 2021 -0500 Merge pull request #78 from zakv/setup-logging-jupyter Make setup_logging() more Jupyter-friendly. commit d309a5f Merge: d5dfea7 12db878 Author: David Meyer <[email protected]> Date: Wed Nov 10 17:06:02 2021 -0500 Merge pull request #82 from dihm/zlog_port_profile Add default zlog port to default profile configuration file. commit c4dd2a8 Author: Zak V <[email protected]> Date: Tue Nov 9 20:12:19 2021 -0500 Removed duplicate call to sys.stdout.fileno() in setup_logging.setup_logging(). Probably best practice to call it just once rather than calling it first to check if it raises an error then again later to actually use the value it returns. commit 2e38107 Author: Zak V <[email protected]> Date: Tue Nov 9 20:04:37 2021 -0500 Restructured try/except block in setup_logging.setup_logging() to avoid catching any UnsupportedOperation errors thrown by code other than sys.stdout.fileno(). commit 97e70c7 Author: Zak V <[email protected]> Date: Tue Nov 9 19:56:07 2021 -0500 Added warning message when setup_logging.setup_logging() cannot send output to stdout and stderr. commit b711923 Author: Zak V <[email protected]> Date: Mon Jun 7 17:48:41 2021 -0400 setup_logging.py is now more Jupyter-friendly. commit d5dfea7 Merge: 9b76dcb b149e19 Author: David Meyer <[email protected]> Date: Wed Nov 10 08:54:21 2021 -0500 Merge pull request #74 from zakv/unitconversions-import-bugfix Fixed bug in unitconversions._All._import_all() commit 12db878 Author: David Meyer <[email protected]> Date: Mon Nov 8 10:20:28 2021 -0500 Add default zlog port to default profile configuration file. commit 9b76dcb Merge: e13c992 e5cf3fb Author: David Meyer <[email protected]> Date: Fri Oct 22 17:53:17 2021 -0400 Merge pull request #80 from dihm/default_labconfig_docs Add default labconfig file to docs commit a3be0db Author: chrisjbillington <[email protected]> Date: Tue Sep 21 13:45:13 2021 +1000 Fix bug on Python3.6, where Path object not able to be treated as a string in ConfigParser. commit e5cf3fb Author: David Meyer <[email protected]> Date: Tue Aug 31 15:29:45 2021 -0400 Create a doc page that displays the current default labconfig.ini file, for easy reference. commit e13c992 Merge: e74472c 461dc9f Author: David Meyer <[email protected]> Date: Fri Jul 16 15:12:37 2021 -0400 Merge pull request #79 from dihm/labscript_utils-docs Update docs to match autogenerating templates used in other modules of labscript. commit 461dc9f Author: David Meyer <[email protected]> Date: Thu Jul 15 10:26:41 2021 -0400 Add docstring coverage test to build. commit f90a4cc Author: David Meyer <[email protected]> Date: Thu Jul 15 10:26:26 2021 -0400 Update sphinx version. commit e45107d Author: David Meyer <[email protected]> Date: Mon Jul 12 12:57:18 2021 -0400 Converting docs build to fully automated version based on recursive autosummary calls. This more closely resembles how docs are built in the other modules, but is slightly different in that submodules are also recursively generated. commit 56d64f7 Author: David Meyer <[email protected]> Date: Mon Jul 12 09:25:18 2021 -0400 Update sphinx pins to same versions as rest of suite. commit e74472c Merge: f0999f5 c543328 Author: Chris Billington <[email protected]> Date: Tue Feb 9 08:54:16 2021 +1100 Merge pull request #76 from zakv/fix-27 Work around infinite recursion in ToolPalette.resizeEvent() commit c543328 Author: Zak V <[email protected]> Date: Mon Feb 8 13:30:47 2021 -0500 Removed some python 2 debugging print statements from toolpalette.py. commit d9eb80f Author: Zak V <[email protected]> Date: Sun Feb 7 23:44:47 2021 -0500 Fixed #27; worked around bug where ToolPalette.resizeEvent() could trigger itself in an infinite resursion loop. commit f0999f5 Merge: 8371585 7d14b65 Author: Chris Billington <[email protected]> Date: Mon Jan 4 13:46:54 2021 +1100 Merge pull request #75 from chrisjbillington/master Do not use deprecated set-env command commit 7d14b65 Author: chrisjbillington <[email protected]> Date: Mon Jan 4 13:40:14 2021 +1100 Do not use deprecated set-env command commit b149e19 Author: Zak V <[email protected]> Date: Tue Nov 24 18:06:11 2020 -0500 Fixed bug in unitconversions._All._import_all() where self.__all__ wasn't always changed from None to an empty list before appending things to it.
commit 95965b8 Merge: a88582d f2f0ac7 Author: Chris Billington <[email protected]> Date: Thu Mar 17 08:02:09 2022 +1100 Merge pull request #86 from dihm/replace_distutils Replace distutils commit f2f0ac7 Author: David Meyer <[email protected]> Date: Wed Mar 16 09:43:51 2022 -0400 Replace `distutils.log` with basic `logging` in `setup.py`. commit b6b7823 Author: David Meyer <[email protected]> Date: Wed Mar 16 09:04:46 2022 -0400 Replace `distutils.sysconfig` with stdlib `sysconfig` in `modulewatcher`. commit 9840228 Author: David Meyer <[email protected]> Date: Wed Mar 16 09:04:10 2022 -0400 Replace `distutils.version.LooseVersion` with `packaging.version.Version` in `ls_zprocess`. commit a88582d Merge: 66c68ab 75a7df6 Author: David Meyer <[email protected]> Date: Thu Mar 3 09:28:57 2022 -0500 Merge pull request #84 from dihm/generic_freq_conv Add generic frequency conversion class commit 75a7df6 Author: David Meyer <[email protected]> Date: Wed Feb 9 12:27:17 2022 -0500 Add generic frequency conversion class that goes between standard SI prefixes from a base of Hz. commit 66c68ab Merge: 7a3d58c 27501a3 Author: David Meyer <[email protected]> Date: Wed Feb 9 10:47:36 2022 -0500 Merge pull request #83 from dihm/fix_docs_build Prevent starting a zlock server when importing `h5_lock` on RTD. commit 27501a3 Author: David Meyer <[email protected]> Date: Wed Feb 9 10:34:22 2022 -0500 Prevent starting a zlock server when importing `h5_lock` on RTD. commit 7a3d58c Author: David Meyer <[email protected]> Date: Wed Feb 2 17:24:26 2022 -0500 Pin `mistune` to fix doc builds on RTD. commit 36c3c6a Author: chrisjbillington <[email protected]> Date: Fri Jan 7 17:23:48 2022 +1100 Ensure only ints passed to QFrame.move in splash Otherwise this is a TypeError in the latest PyQt5. commit f4da12e Author: David Meyer <[email protected]> Date: Tue Nov 30 13:00:27 2021 -0500 Triggering build of release branch by undoing unnecessary pin change for pyqtgraph. commit a79d0e4 Author: David Meyer <[email protected]> Date: Tue Nov 30 11:20:27 2021 -0500 Update setup.cfg in preparation for release. commit 811b43d Merge: b8726ad a3be0db Author: David Meyer <[email protected]> Date: Wed Nov 10 17:07:51 2021 -0500 Merge pull request #81 from chrisjbillington/py36-path-bug Fix bug on Python3.6 commit b8726ad Merge: d309a5f c4dd2a8 Author: David Meyer <[email protected]> Date: Wed Nov 10 17:06:47 2021 -0500 Merge pull request #78 from zakv/setup-logging-jupyter Make setup_logging() more Jupyter-friendly. commit d309a5f Merge: d5dfea7 12db878 Author: David Meyer <[email protected]> Date: Wed Nov 10 17:06:02 2021 -0500 Merge pull request #82 from dihm/zlog_port_profile Add default zlog port to default profile configuration file. commit c4dd2a8 Author: Zak V <[email protected]> Date: Tue Nov 9 20:12:19 2021 -0500 Removed duplicate call to sys.stdout.fileno() in setup_logging.setup_logging(). Probably best practice to call it just once rather than calling it first to check if it raises an error then again later to actually use the value it returns. commit 2e38107 Author: Zak V <[email protected]> Date: Tue Nov 9 20:04:37 2021 -0500 Restructured try/except block in setup_logging.setup_logging() to avoid catching any UnsupportedOperation errors thrown by code other than sys.stdout.fileno(). commit 97e70c7 Author: Zak V <[email protected]> Date: Tue Nov 9 19:56:07 2021 -0500 Added warning message when setup_logging.setup_logging() cannot send output to stdout and stderr. commit b711923 Author: Zak V <[email protected]> Date: Mon Jun 7 17:48:41 2021 -0400 setup_logging.py is now more Jupyter-friendly. commit d5dfea7 Merge: 9b76dcb b149e19 Author: David Meyer <[email protected]> Date: Wed Nov 10 08:54:21 2021 -0500 Merge pull request #74 from zakv/unitconversions-import-bugfix Fixed bug in unitconversions._All._import_all() commit 12db878 Author: David Meyer <[email protected]> Date: Mon Nov 8 10:20:28 2021 -0500 Add default zlog port to default profile configuration file. commit 9b76dcb Merge: e13c992 e5cf3fb Author: David Meyer <[email protected]> Date: Fri Oct 22 17:53:17 2021 -0400 Merge pull request #80 from dihm/default_labconfig_docs Add default labconfig file to docs commit a3be0db Author: chrisjbillington <[email protected]> Date: Tue Sep 21 13:45:13 2021 +1000 Fix bug on Python3.6, where Path object not able to be treated as a string in ConfigParser. commit e5cf3fb Author: David Meyer <[email protected]> Date: Tue Aug 31 15:29:45 2021 -0400 Create a doc page that displays the current default labconfig.ini file, for easy reference. commit e13c992 Merge: e74472c 461dc9f Author: David Meyer <[email protected]> Date: Fri Jul 16 15:12:37 2021 -0400 Merge pull request #79 from dihm/labscript_utils-docs Update docs to match autogenerating templates used in other modules of labscript. commit 461dc9f Author: David Meyer <[email protected]> Date: Thu Jul 15 10:26:41 2021 -0400 Add docstring coverage test to build. commit f90a4cc Author: David Meyer <[email protected]> Date: Thu Jul 15 10:26:26 2021 -0400 Update sphinx version. commit e45107d Author: David Meyer <[email protected]> Date: Mon Jul 12 12:57:18 2021 -0400 Converting docs build to fully automated version based on recursive autosummary calls. This more closely resembles how docs are built in the other modules, but is slightly different in that submodules are also recursively generated. commit 56d64f7 Author: David Meyer <[email protected]> Date: Mon Jul 12 09:25:18 2021 -0400 Update sphinx pins to same versions as rest of suite. commit e74472c Merge: f0999f5 c543328 Author: Chris Billington <[email protected]> Date: Tue Feb 9 08:54:16 2021 +1100 Merge pull request #76 from zakv/fix-27 Work around infinite recursion in ToolPalette.resizeEvent() commit c543328 Author: Zak V <[email protected]> Date: Mon Feb 8 13:30:47 2021 -0500 Removed some python 2 debugging print statements from toolpalette.py. commit d9eb80f Author: Zak V <[email protected]> Date: Sun Feb 7 23:44:47 2021 -0500 Fixed #27; worked around bug where ToolPalette.resizeEvent() could trigger itself in an infinite resursion loop. commit f0999f5 Merge: 8371585 7d14b65 Author: Chris Billington <[email protected]> Date: Mon Jan 4 13:46:54 2021 +1100 Merge pull request #75 from chrisjbillington/master Do not use deprecated set-env command commit 7d14b65 Author: chrisjbillington <[email protected]> Date: Mon Jan 4 13:40:14 2021 +1100 Do not use deprecated set-env command commit b149e19 Author: Zak V <[email protected]> Date: Tue Nov 24 18:06:11 2020 -0500 Fixed bug in unitconversions._All._import_all() where self.__all__ wasn't always changed from None to an empty list before appending things to it.
Original report (archived issue) by Chris Billington (Bitbucket: cbillington, GitHub: chrisjbillington).
A lab here at NIST got a "Python has stopped working" error upon starting BLACS today. Starting Python as
python -X faulthander -m blacsrevealed it to be a stack overflow inToolPalette._layout_widgets(), line 348:Adding a printline to inspect the dimensions of the
QSize()object revealed that_layout_widgets()was being called a large number of times prior to the crash, with the dimensions alternating back and forth between two values.I added a counter to print the recursion depth and confirm that the method is recursing, but I made a syntax error and BLACS started successfully (having caught the error), modifying its save file and widget geometries such that the stack overflow no longer occurred. So unfortunately I lost the ability to reproduce the problem, as it is sensitive to the widget geometries.
Just documenting what I found here.
ToolPalette._layout_widgets()seems to be recursing and not converging on a fixed layout geometry that would break the cycle. If I see it again I will backup BLACS save file and connection table file to create a reliable reproducer of the problem.Others have reported similar crashes before, but they have not been stack overflows, they have been segfaults that looked to be bugs in Qt. This one actually is plausibly our fault which means we may be able to fix it.
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