Command-line Tool to find Java Heap Size and Memory Used (Linux)?

Question

Do we have the Command-line Tool (Linux) to check the Heap Size (and Used Memory) of the Java Application?

I have tried through the jmap. But it gives info. about the internal memory areas like Eden/ PermGen etc., which is not useful to me.

This is what I am looking for:

• Max Memory: 1GB
• Min Memory: 256 MB
• Heap Memory: 700 MB
• Used Memory: 460 MB

That's all. I know that I can see this in the JConsole etc., but I need the command-line tool (can't enable JMX etc.)

Do you know any such tool/ command?

Answer 1

Each Java process has the pid, which you first need to find with a jps command.

Once you have a pid, you can use jstat -gc [insert-pid-here] to find statistics of this behavior of this garbage collected heap.

• The jstat -gccapacity [insert-pid-here] will present information about memory pool generation and space capabilities.
• The jstat -gcutil [insert-pid-here] will present the utilization of each generation as the percentage of its capacity. Useful to get an at glance view of usage.

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