A simple JVM heap size monitoring tool
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During my short career as a DevOps engineer, I came across a JVM heap monitoring task and soon found out that there was no easy way of getting the heap usage of a running JAVA process without wrapping bash calls to jstat and using bc in order to just get a plain string output. No easy way to integrate into other DevOps scripts using a starndardized Data output format. Well, Jotun is made up to do just that. Get real time info on the heap usage of any JAVA process plus some overall RAM usage stats and then output it neatly in JSON format for easy integration to other custom tools.
For the time being jotun is only available for UNIX operating systems (Linux & MacOS)
First download the latest version of jotun from here
then for UNIX operating system you can run jotun in the directory of your choice by calling the absolute path to jotun executable or you can copy the executable to /usr/local/bin, so it can be available for all users and from every directory, use the following command to do so (qwill probably need sudo privileges):
sudo cp /{whatever_download_dir}/jotun /usr/local/bin/jotun
To install the man page as well download the tar.gz file from here and untar it like this:
tar -xvzf jotun-1.0.0-alpha.tar.gz -C ./whatever/
then cd into the whatever folder and run the installer (needs sudo) like this:
sudo ./installer.sh
or you can just download the deb package and install it like this:
sudo dpkg -i jotun-1.0.0-beta.deb
Monitor a single PID
to use it you can either run it like jotun if you installed it in /usr/local/bin or by ./{PATH_TO_Jotun}
To monitor the heap usage of a single JAVA process use:
./jotun -p PID_of_the_process_you_wish_to_monitor
The output will be something like that:
{"Pid":"4207","PidName":"javaApp.jar","Heap":"27846.90","Format":"kB","AvailableRAM":"16316300.00","FreeRAM":"12117944.00"}
- In order for jotun to work, it needs to be ran as the user of the pid you wish to get data for.
- Keep in mind that the output's default unit of measurement is kB. (for fields: Heap, AvailableRAM and FreeRAM). If you wish to display the output in MB, Bytes or GB, you can use the -h flag like this:
./jotun -p PID_of_the_process_you_wish_to_monitor -h kB
Currently only B, kB, MB and GB representations are supported. (kB is the default one).
The output is rounded up to 2 decimal points for any chosen representation.
Monitor a PID list
To monitor a PID list of Java processes, you can use the --pid-list flag like this:
./jotun --pidlist 123,456,789
Note that the separator is ,
The JSON output would be like this:
{"PidLlist":[{"Pid":"456","PidName":"java3.jar","Heap":"27846.90","Format":"kB","AvailableRAM":"16316300.00","FreeRAM":"12106400.00"},{"Pid":"123","PidName":"java2.jar","Heap":"27846.90","Format":"kB","AvailableRAM":"16316300.00","FreeRAM":"12106400.00"},{"Pid":"789","PidName":"java3.jar","Heap":"27846.90","Format":"kB","AvailableRAM":"16316300.00","FreeRAM":"12106400.00"}]}
Monitor all JAVA running processes
To monitor all JAVA processes running on the machine, you will need the --all flag. No need to specify any pid, jotun will find everything itself. You can use it like this:
./jotun --all
The output will have the same format and schema as the one above for the pid list. Example:
{"PidLlist":[{"Pid":"456","PidName":"java3.jar","Heap":"27846.90","Format":"kB","AvailableRAM":"16316300.00","FreeRAM":"12106400.00"},{"Pid":"123","PidName":"java2.jar","Heap":"27846.90","Format":"kB","AvailableRAM":"16316300.00","FreeRAM":"12106400.00"},{"Pid":"789","PidName":"java3.jar","Heap":"27846.90","Format":"kB","AvailableRAM":"16316300.00","FreeRAM":"12106400.00"}]}
Jotun is a free program under the MIT license and will remain that way forever. Please feel free to report any issues or development requests through github's ticketing system. Feel free to Fork and enjoy yourself as well.
Hope you'll find it useful