byobu killed by 'CTRL-C' + 'q' since Ubuntu 14.04

[Mario Emmenlauer]

I've been using byobu with Ubuntu since many years. One thing I do is follow logfiles with 'less'. To abort less following the file, the key combination 'CTRL-C' is used, and to exit less, I subsequently press 'q'. I do this many times a day, and never had problems until Ubuntu 14.04, when it started to sometimes kill byobu (randomly, on average in maybe one out of twenty cases). I could not yet isolate the underlying cause why it does not always crash. But when it crashes, it will happen exactly when pressing 'q' to exit less after having previously pressed 'CTRL-C'.
I do not recall the exact message of the crash, its something like "killed with signal".

byobu:all/trusty-updates 5.77-0ubuntu1.2 uptodate

[Dustin Kirkland  (kirkland)]

Hi, thanks for the report.

I can't seem to reproduce this myself, though I've tried.

Could you perhaps record a screencast of this happening?

[Mario Emmenlauer (emmenlau)]

Hi, thanks for the quick feedback!
I can not easily reproduce the behavior myself, on average it will happen once per 2-3 weeks, during which time I use the key combination 'CTRL-C' + 'q' maybe between 30-100 times. I never occurred within the first days, but there is also no pattern after how much time it might appear.

A wild guess: is maybe byobu (or screen or tmux) reserving or freeing large amounts of memory while I follow my logfiles? Could the closing of 'less' coincide with a larger mem-free that somehow could trigger a signal? Its a rather wild guess, but it might explain why typically it takes 10-20 days before I suddenly get the crash. Is there anything else that "accumulates"? I have ~10 sessions open in byobu, and not a specifically high cpu load.

[Mario Emmenlauer (emmenlau)]

The crash just happened again. byobu was running for something like two weeks without problems. This time,
the circumstances where slightly different: To exit 'less' without pressing 'CTRL-C' directly followed by 'q', I use
instead now the following key combination: 'CTRL-C' + 'up' + 'up' + 'q'. I hoped this might help, but it did not.
I even wait a few seconds before pressing 'q'. But at the very instant I press the 'q'-key, less will end, and byoby
will crash. I think the crash is somehow related to 'less' ending, or to pressing 'q'. The exact crash message is:
[screen caught signal 11. (core dumped)]

The specs shown in byobu's status bar are:
^307kb v172kb (R) 1# 112d2h 0.08 8x0.8GHz 31.3GB44% 2015-09-21 10:46:28

There is nothing in syslog or dmesg that seems related. Anything I can try to debug this? Please help! :-(

[Mario Emmenlauer (emmenlau)]

I'm still plagued by this issue! This time I tried something slightly different: I
pressed 'CTRL'-'C' to break 'less', then I switched byobu terminals with 'CTRL'-'left'
and 'CTRL'-'right', then pressed 'q' to exit 'less'. byobu crashed again, exactly at the
time I pressed 'q'! So this time, I'm certain that the core dump must be directly
related to pressing 'q'. And it only happens in 'less', after previously pressing
'CTRL'-'C'. Any help would be greatly appreciated!