For the hello world app you can probably set -Xms and -Xmx to 5m, so java -Xms5m -Xmx5m Program. Xms sets the initial heap size, Xmx sets the max. There are lots of memory areas besides the heap though, as mentioned in the above post, so this will still use maybe 50MiB of memory or more.
As for figuring out what you should set for a given program, that generally takes a bit of profiling while the app is running with tools like jmap, jconsole, visualvm etc... Or just plain trial and error in some cases.
I wrote a post a while back that goes into a bit of depth around jvm memory usage, see
JVM Internals: Memory Overview
Stephen O'Brien ・ Jan 22 ・ 12 min read
For the hello world app you can probably set
-Xmsand-Xmxto 5m, sojava -Xms5m -Xmx5m Program. Xms sets the initial heap size, Xmx sets the max. There are lots of memory areas besides the heap though, as mentioned in the above post, so this will still use maybe 50MiB of memory or more.As for figuring out what you should set for a given program, that generally takes a bit of profiling while the app is running with tools like jmap, jconsole, visualvm etc... Or just plain trial and error in some cases.
Thank you very much, very informative post! :)
I'm going to learn one of those tools, right now I feel clueless about anything related to memory
There is definitely a lot to learn, I'm still learning new things most days! Good luck 👍
I'm going to do a more practical post around tuning the jvm soon.