Generating thread dumps via shell script

The generateThreadDumps.sh script within this article utilizes a looped execution of Java's native jstack utility to generate a configurable quantity of thread dumps with a configurable frequency.

Script usage

Within the script file, modify the java_dir variable to your Java installation directory. You can also optionally update the output_dir variable if you want the thread dumps to output to a location besides your present working directory (pwd). 

Next, the script can be run with the following syntax:

./generateThreadDumps.sh <pid> [ <quantity> [ <frequency> ] ]

<pid> is the PID of the Java process for the thread dumps

<quantity> is an optional value of the amount of thread dumps to create (default: 3)

<frequency> is an optional value of the duration in seconds between each thread dump (default: 60)

Note that the <frequency> does not include the time required to make the thread dump itself. This is primarily noticeable with very frequent execution, such as one second. If a thread dump takes 0.5 seconds to complete with a frequency set as 1, then the thread dumps are created once per 1.5 seconds.

Setting <frequency> to zero will create the thread dumps in sequence. 

Script download

Download generateThreadDumps.sh or copy the code below into a file:

#!/bin/sh

# Modify with your Java installation directory
java_dir=

# Optionally modify with the output directory for thread dumps
output_dir=$PWD


if [ ! $java_dir ]
then
  echo ""
  echo "Modify java_dir within this script with your Java installation directory"
  echo ""  
  exit 1
fi

if [ $# -ne 0 ]
then
  pid=$1
  
  # Checks if PID exists
  if ps -p $pid > /dev/null 
  then
    # Default to 3 thread dumps, unless parameter 2 is specified 
    quantity=${2:-3}
    
    # Default to one thread dump per 60 seconds, unless parameter 3 is specified 
    frequency=${3:-60}
    
    echo ""  
    echo "Collecting $quantity thread dumps $frequency seconds apart for PID $1"
    echo ""
    
    current_count=0
    
    # Loop through each thread dump execution
    while [ $current_count -lt $quantity ] 
    do
      current_time=$(date "+%Y.%m.%d-%H.%M.%S.%N")
    
      # Generate thread dump via jstack
      $java_dir/bin/jstack $pid > $output_dir/thread_dump_$current_time
    
      # If you need to generate thread dumps for a hung process, then comment
      # out the line above and uncomment the line below. This includes the -F
      # flag to force a thread dump
      # $java_dir/bin/jstack -F $pid > $output_dir/thread_dump_$current_time
    
      ((current_count++))
      echo "Thread dump #$current_count collected at $current_time"
    
      # Sets a delay only if this isn't the last execution
      if [ $current_count -lt $quantity ]
      then
        sleep $frequency
      fi
    done
    
    echo ""  
    echo "Thread dump collection complete"
    echo ""
  else
    echo ""
    echo "The PID $1 does not exist"
    echo ""  
    exit 1
  fi
else
  echo ""
  echo "Specify the PID of the Java process to generate thread dumps."
  echo ""
  echo "Usage: ./generateThreadDumps.sh <pid> [ <quantity> [ <frequency> ] ] "
  echo ""
  exit 1
fi