Dear Maintainer,
Since an "apt-get update && apt-get dist-upgrade" on Debian Sid about
one or two months ago starting GNU screen or any new tab within hangs
for about 10-15 seconds. During that time the SCREEN process is seen
with 100% CPU usage in htop.
I could narrow the issue down to the "unlimit" line at the very start of
my ~/.zshrc. I think I had added this one (plus "limit stack 8192" and
"limit core 0" a long time ago to enable coredumps of crashing
processes with systemd-coredump / coredumpctl. However this issue only
appeared after the update in the last one or two months.
Removing the "unlimit" line from my ~/.zshrc fixes the problem.
The following line should be sufficient to reproduce the problem, too:
$ zsh -c "unlimit; screen"
I also ran "perf record -g -F 99 -- timeout 10 screen" to create a
~/perf.data file of the hang and then ran
"perf report -n --stdio > ~/perf.data-report.txt", as well and created a
FlameGraph SVG [0]. See attachments (SVG is interactive in a browser).
However, even though I had screen-dbgsym installed, I don't quite
understand what in GNU screen is calling (looping around?) __poll(),
which seems to create the main busyness, seems like there is a
missing symbol for that.
This is on a recent Debian Sid, with Linux 6.9.8-amd64 / 6.9.8-1.
Regards, Linus
[0]: https://brendangregg.com/FlameGraphs/cpuflamegraphs.html
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