Creating a thread dump series

This articles explains how to create a thread dump series, which can be a useful tool to investigate unexpected behaviour.

Instructions

On a virtual machine

1. Create a run script called jStackSeries.sh that looks as follows on your HiveMQ machine
   

   #!/bin/bash
   if [ $# -eq 0 ]; then
       echo >&2 "Usage: jstackSeries <pid> <run_user> [ <count> [ <delay> ] ]"
       echo >&2 "    Defaults: count = 10, delay = 0.5 (seconds)"
       exit 1
   fi
   pid=$1          # required
   user=$2         # required
   count=${3:-10}  # defaults to 10 times
   delay=${4:-0.5} # defaults to 0.5 seconds
   while [ $count -gt 0 ]
   do
       sudo -u $user jstack -l $pid >jstack.$pid.$(date +%H%M%S.%N)
       sleep $delay
       let count--
       echo -n "."
   done

2. Find the HiveMQ run user <user> and process ID <pid> by running ps aux | grep hivemq

3. Run the script as follows:
   sh jStackSeries-docker.sh <pid> <user> 20

4. This will result in 20 files (filename: 'jstack.<pid>.<date>.N') being generated

5. Please pack these 20 files in a zip file and attach them to your HiveMQ Support issue

 In docker

1. Create the following run run-script jstack-series.sh
   

   #!/bin/bash
   if [ $# -eq 0 ]; then
       echo >&2 "Usage: jstackSeries [ <count> [ <delay> ] ]"
       echo >&2 "    Defaults: count = 10, delay = 0.5 (seconds)"
       exit 1
   fi
   count=${1:-20}  # defaults to 10 times
   delay=${2:-0.5} # defaults to 0.5 seconds
   while [ $count -gt 0 ]
   do
       ./jattach 1 threaddump>jstack.$pid.$(date +%H%M%S.%N)
       sleep $delay
       let count--
       echo -n "."
   done

2. Run the following inside your Docker container:
   

   curl -L https://github.com/apangin/jattach/releases/download/v1.5/jattach > jattach && \
   chmod +x jattach

3. Run the created script: ./jstack-series.sh

4. This will result in 20 files (filename: 'jstack.<pid>.<date>.N') being generated

5. Please pack these 20 files in a zip file and attach them to your HiveMQ Support issue