Braille display auto-detection feature causes errors on loading large braille tables on NVDA startup

[DrSooom]

First of all I'm so glad that these errors aren't caused by my HUC Braille Tables alone, because other large braille tables like "zh-tw.ctb" lead to the same results I described in issue #9973 yesterday. CC: @LeonarddeR

Steps to reproduce:

1. Install/Create a portable copy of NVDA 2019.2 Beta-18176.
2. Now start NVDA Portable and change the braille output table to Chinese Taiwan/Mandarin ("zh-tw.ctb") and disable the checkbox "Expand to computer braille for the word at the cursor".
3. Restart NVDA with debug logging level via NVDA+Q.

Actual behavior:

This time I was able to reproduce both errors I mentioned in issue #9973 on a SSD, but I couldn't figure out if the Chinese braille table "zh-tw.ctb" (of course without the HUC Braille Tables) was completely loaded or not. Maybe you have to restart NVDA multiple times to get these errors.

Here is the first logfile with no error sound on startup. And here is the second one with an error sound and no braille output directly after startup. Always start at line 126. And please take a look at the timestamps in the second logfile, because there aren't any log entries from the beginning of the error sound until the Protocol Viewer was opened. That's so strange, therefore I repeated restarting NVDA in Debug Mode multiple times, because I thought I did something wrong. Normally NVDA should also have logged pressing ArrowRight and ArrowLeft in the Windows Explorer (Detail View) as well as the steps to open the Protocol Viewer via the NVDA menu. But that was never the case.

Expected behavior:

No errors on loading large braille tables.

• zh-tw.ctb: 1,25 MB (1,306,176 Bytes); 48,769 lines

System configuration

NVDA installed/portable/running from source:

Portable

NVDA version:

2019.2 Beta-18176

Windows version:

Win7x64

Other information about your system:

Optelec ALVA BC680 is connected via USB2. The USB1 port wasn't tested.

Other questions

Does the issue still occur after restarting your PC?

Not tested.

Have you tried any other versions of NVDA? If so, please report their behaviors.

Tests with 2019.1.1 (Portable) are pending. But I guess it's the same behavior like in issue #9973 – it works as expected. And smaller braille tables such as the Finish 8-dot Computer Braille ("fi-fi-8dot.ctb") seems to work with NVDA 2019.2 Beta-18176 as expected too. But deeper tests are pending here too.

[zstanecic]

Hmmmm, Is it something to do with your NVDA configuration profile, or really some weird regression? I cannot reproduce this on the latest alpha, powered by py3

[DrSooom]

That were/are always fresh portable Betas of NVDA. NVDA 2018.1 is installed on my system. Here is my config file. I guess it's a regression. Furthermore you can't compare these Betas with the Py3-Alphas because of PR #9544 and #9545.

[zstanecic]

Ah, I see But i am still wondering

[LeonarddeR]

Do you have reasons to think that this is a bug in NVDA and not in liblouis?

[DrSooom]

@LeonarddeR: You ask me things? That could be also caused by the Liblouis update from 3.8.0 to 3.10.0 over 3.9.0. This issue didn't occur in NVDA 2019.1.1 with Liblouis 3.8.0.

Therefore: CC: @bertfrees, @egli, @dkager and @nishimotz (if you are using Liblouis).

[lukaszgo1]

@DrSooom Could you please test this with the last Python 2 Alpha of NVDA available here. I am asking because in issue #9486 the errors are similar, and it is caused by liblouis builds being optimized. If my hypothesis would be correct perhaps disabling optimization for liblouis builds for the time being would be reasonable. @LeonarddeR What do you think?

[DrSooom]

NVDA Alpha-18064 logfile on loading "zh-tw.ctb" after NVDA restart in Debug Mode:

Initializing global plugin handler
DEBUGWARNING - braille.BrailleHandler.setDisplayByName (20:39:28.825):
Error in initial display after display load
Traceback (most recent call last):
  File "braille.pyc", line 1686, in setDisplayByName
  File "braille.pyc", line 1976, in initialDisplay
  File "braille.pyc", line 1840, in handleGainFocus
  File "braille.pyc", line 1845, in _doNewObject
  File "braille.pyc", line 1516, in getFocusRegions
  File "braille.pyc", line 615, in update
  File "braille.pyc", line 428, in update
  File "louisHelper.pyc", line 65, in translate
  File "louis\__init__.pyc", line 183, in translate
WindowsError: exception: access violation reading 0x08DF7608
IO - braille.BrailleBuffer.update (20:39:29.046):
Braille regions text: [u'NVDA ist bereit']
IO - braille.BrailleHandler.update (20:39:29.046):
Braille window dots: 13457 12367 1457 17 - 24 234 2345 - 12 15 1235 15 24 2345
DEBUG - core.main (20:39:29.048):
Initializing core pump

And here is the complete logfile (start at line 149) after NVDA Alpha-18064 (Portable on a SSD) totally crashed after a few more restarts in Debug Mode. Only the Windows Explorer was opened during these tests. The HUC Braille Tables weren't tested.

[AAClause]

Hi,
I've just tested and I wasn't able reproduce this bug. Tested with 2019rc1 and alpha-18222,be63d19d (portable versions). I Restarted NVDA about 10 times.

[DrSooom]

@Andre9642: Regarding NVDA 2019.2 RC1 I can confirm this. I also didn't get any errors. I wonder why. Therefore: Closing for now.

[DrSooom]

This issue is back in NVDA 2019.2 RC2 (portable). Here is the logfile with "zh-tw.ctb" and freezing on startup (which wasn't logged, because I was able to kill the process "nvda.exe" via the Task Manager). The HUC Braille Tables are also affected.

[DrSooom]

A nice new log entry with NVDA 2019.2 Beta-18345 on startup. Complete logfile

RuntimeError: Can't translate: tables [u'louis\tables\zh-tw.ctb', 'braille-patterns.cti'], inbuf N V D A i s t b e r e i t , typeform None, cursorPos c_long(0), mode 4

Note: There is a strange character between the letters in the logfile, It's not a space (U+0020) – maybe CR, LF or CRLF together.
CC: @LeonarddeR, @zstanecic, @bertfrees and @egli