-ss option and --log does not work correctly sometimes.

[greymd]

Reproduced Environment:
Docker on macOS 10.12.06 Sierra + Docker(18.06.0-ce-mac70)
container: ubuntu:18.04
tmux version: 2.4
bash version: 3.2.0

$ xpanes --debug -ss --log=~/logs --log-format="[:ARG:]" -I@ -d -c "echo TEST | sed s/TEST/@/" AAAA BBBB CCCC DDDD

# Expected
## ~/logs/AAAA-1 => AAAA
## ~/logs/BBBB-1 => BBBB
## ~/logs/CCCC-1 => CCCC
## ~/logs/DDDD-1 => DDDD

# Actual (sometimes)
## ~/logs/AAAA-1 => AAAA
## ~/logs/BBBB-1 => BBBB
## ~/logs/CCCC-1 => !!EMPTY!!
## ~/logs/DDDD-1 => DDDD

# $ cat ~/logs/CCCC-1
# => nothing

Same problem seems happened on the TravisCI link.

tmux pipe-pane is used for the logging feature of tmux-xpanes.
During the development for version 3.1.0, I noticed, the logging feature does not work correctly sometimes.
It seems that, running multiple pipe-pane processes does not work correctly.

Here is PoC.

1. Creating multiple named pipes.
2. Split tmux panes and start the processes to wait each named pipe updated.
3. Run tmux pipe-pane to redirect each pane's stdout.
4. Notify all the named pipes.
5. Some results of the pipe-pane is empty. Frequently.

#!/bin/bash

# Try this script on the docker container.
# Tested on macoOS High Sierra + Ubuntu 18.04 docker container.

rm -f "$HOME"/work/*

tmux -S "$HOME"/work/sess new-session -d

printf "%s\\n" A B C D | while read -r f;do
  mkfifo "$HOME/work/$f"
  echo "start to wait: mkfifo $HOME/work/$f"
  _pane_id=$( tmux -S "$HOME"/work/sess splitw -P "grep -q 1 $HOME/work/$f"$'\n'"echo 'This is $f'" )
  echo "start logging: pipe-pane cat >> $HOME/work/$f.log"
  tmux -S "$HOME"/work/sess pipe-pane -t "$_pane_id" "cat >> $HOME/work/$f.log"
done

printf "%s\\n" A B C D | while read -r f;do
  echo "notify to $f"
  printf "%s\\n" 1 > "$HOME/work/$f" &
done

sleep 5

printf "%s\\n" "$HOME/work"/*.log | while read -r file;do
  echo "$file"
  cat "$file"
done

# $ bash fifo.sh
# start to wait: mkfifo /home/docker/work/A
# start logging: pipe-pane cat >> /home/docker/work/A.log
# start to wait: mkfifo /home/docker/work/B
# start logging: pipe-pane cat >> /home/docker/work/B.log
# start to wait: mkfifo /home/docker/work/C
# start logging: pipe-pane cat >> /home/docker/work/C.log
# start to wait: mkfifo /home/docker/work/D
# start logging: pipe-pane cat >> /home/docker/work/D.log
# notify to A
# notify to B
# notify to C
# notify to D
# /home/docker/work/A.log
# This is A
# /home/docker/work/B.log
# This is B
# /home/docker/work/C.log <<<<<<<<<<<<<<<<<<< EMPTY !!!
# /home/docker/work/D.log <<<<<<<<<<<<<<<<<<< EMPTY !!!

[greymd]

Even sleep command is inserted any part, the problem is reproduced..

[greymd]

It seems that, this is caused by https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=865756

[greymd]

Same issue does not reproduced in tmux 2.7.
Therefore, it would be known bug in tmux.
(--log feature does not work in tmux 2.3 due to Known Bug. That's why status is green.)

[greymd]

This issue seems fixed in tmux 2.6 and more.
https://travis-ci.org/greymd/tmux-xpanes/builds/410575182

[greymd]

Let me update Known Bug page.
/~https://github.com/greymd/tmux-xpanes/wiki/Known-Bugs

[greymd]

Fixed at v3.1.0