Parallel subshells doing work and report status - bash

Question

I am trying to do work in all subfolders in parallel and describe a status per folder once it is done in bash.
suppose I have a work function which can return a couple of statuses
#param #1 is the folder
# can return 1 on fail, 2 on sucess, 3 on nothing happend
work(){
cd $1
// some update thing
return 1, 2, 3
}
now I call this in my wrapper function
do_work(){
while read -r folder; do
tput cup "${row}" 20
echo -n "${folder}"
(
ret=$(work "${folder}")
tput cup "${row}" 0
[[ $ret -eq 1 ]] && echo " \e[0;31mupdate failed \uf00d\e[0m"
[[ $ret -eq 2 ]] && echo " \e[0;32mupdated \uf00c\e[0m"
[[ $ret -eq 3 ]] && echo " \e[0;32malready up to date \uf00c\e[0m"
) &>/dev/null
pids+=("${!}")
((++row))
done < <(find . -maxdepth 1 -mindepth 1 -type d -printf "%f\n" | sort)
echo "waiting for pids ${pids[*]}"
wait "${pids[#]}"
}
and what I want is, that it prints out all the folders per line, and updates them independently from each other in parallel and when they are done, I want that status to be written in that line.
However, I am unsure subshell is writing, which ones I need to capture how and so on.
My attempt above is currently not writing correctly, and not in parallel.
If I get it to work in parallel, I get those [1] <PID> things and [1] + 3156389 done ... messing up my screen.
If I put the work itself in a subshell, I don't have anything to wait for.
If I then collect the pids I dont get the response code to print out the text to show the status.
I did have a look at GNU Parallel but I think I cannot have that behaviour. (I think I could hack it that the finished jobs are printed, but I want all 'running' jobs are printed, and the finished ones get amended).

Answer 1

Assumptions/undestandings:
a separate child process is spawned for each folder to be processed
the child process generates messages as work progresses
messages from child processes are to be displayed in the console in real time, with each child's latest message being displayed on a different line
The general idea is to setup a means of interprocess communications (IC) ... named pipe, normal file, queuing/messaging system, sockets (plenty of ideas available via a web search on bash interprocess communications); the children write to this system while the parent reads from the system and issues the appropriate tput commands.
One very simple example using a normal file:
> status.msgs # initialize our IC file
child_func () {
# Usage: child_func <unique_id> <other> ... <args>
local i
for ((i=1;i<=10;i++))
do
sleep $1
# each message should include the child's <unique_id> ($1 in this case);
# parent/monitoring process uses this <unique_id> to control tput output
echo "$1:message - $1.$i" >> status.msgs
done
}
clear
( child_func 3 & )
( child_func 5 & )
( child_func 2 & )
while IFS=: read -r child msg
do
tput cup $child 10
echo "$msg"
done < <(tail -f status.msgs)
NOTES:
the (child_func 3 &) construct is one way to eliminate the OS message re: 'background process completed' from showing up in stdout (there may be other ways but I'm drawing a blank at the moment)
when using a file (normal, pipe) OP will want to look at a locking method (flock?) to insure messages from multiple children don't stomp each other
OP can get creative with the format of the messages printed to status.msgs in conjunction with parsing logic in the parent's while loop
assuming variable width messages OP may want to look at appending a tput el on the end of each printed message in order to 'erase' any characters leftover from a previous/longer message
exiting the loop could be as simple as keeping count of the number of child processes that send a message <id>:done, or keeping track of the number of children still running in the background, or ...
Running this at my command line generates 3 separate lines of output that are updated at various times (based on the sleep $1):
# no ouput to line #1
message - 2.10 # messages change from 2.1 to 2.2 to ... to 2.10
message - 3.10 # messages change from 3.1 to 3.2 to ... to 3.10
# no ouput to line #4
message - 5.10 # messages change from 5.1 to 5.2 to ... to 5.10
NOTE: comments not actually displayed in console

Answer 2

Based on #markp-fuso's answer:
printer() {
while IFS=$'\t' read -r child msg
do
tput cup $child 10
echo "$child $msg"
done
}
clear
parallel --lb --tagstring "{%}\t{}" work ::: folder1 folder2 folder3 | printer
echo

Answer 3

You can't control exit statuses like that. Try this instead, rework your work function to echo status:
work(){
cd $1
# some update thing &> /dev/null without output
echo "${1}_$status" #status=1, 2, 3
}
And than set data collection from all folders like so:
data=$(
while read -r folder; do
work "$folder" &
done < <(find . -maxdepth 1 -mindepth 1 -type d -printf "%f\n" | sort)
wait
)
echo "$data"