A poor man's visualization

monitor_tasks.sh

#!/usr/bin/env bash
# Code inspired by https://poormansprofiler.org

set -eu

if [ "$#" -ne 1 ]; then
    echo "Usage: $0 <program>"
    exit 0
fi

# If pidof doesn't find a process ID for the given program name, it exits with
# status 1, causing this script to exit as well (set -e).
pid=$(pidof "$1")
sleeptime=0
logfile="${1}_${pid}.log"

# Sample as long as the process is running
while ps -p "$pid" > /dev/null; do
    gdb -ex "thread apply all p deque->num_tasks" -batch -p "$pid" | awk -f print_tasks.awk
    sleep $sleeptime
done > "$logfile"

# Generate script for visualization
visfile="vis_${logfile%.*}.sh"
> "$visfile"

cat > "$visfile" <<CODE
#!/usr/bin/env bash
# Displays sparklines (https://github.com/holman/spark)

set -eu

while read -r line; do
    clear
    printf "\n\n\n\n\n"
    printf "          "
    spark "\$line"
    printf "          "
    echo "\$line" | awk '{
        for (i = 1; i <= NF; i++) {
            if (\$i == 0) printf "0"
            else printf " "
        }
        printf "\n"
    }'
    printf "\n\n\n\n\n"
    sleep 0.3
done < "$logfile"
CODE

chmod u+x "$visfile"

read -p "Start visualization? [y/n] " -n 1
echo

if [[ $REPLY == "y" ]]; then
    ./"$visfile"
fi

print_tasks.awk

# Process debugging output that looks like this:
#
# Thread 8 (Thread 0x7ffff4812700 (LWP 8635)):
# $9 = 3
# 
# Thread 7 (Thread 0x7ffff5013700 (LWP 8634)):
# $10 = 1
# 
# Thread 6 (Thread 0x7ffff5814700 (LWP 8633)):
# $11 = 0
#
# [...]

/^Thread/ {
    curr_thread = $2
}

/^\$/ {
    tasks[curr_thread] = $3
}

END {
    for (i in tasks) {
        printf "%d ", tasks[i]
    }
    printf "\n"
}