How do you determine how much memory to allocate for your applications?

Sufficient memory * 2?

Why do you allocate memory in java? If you'd run out of system memory, gc will do its job.

@ganjaman And while it does so, everything just freezes.

@ganjaman to have a controlled environment.
Also up until some particular version of java8 jvm can kill docker container if run w/o heap limitations

To OP: stress tests, imitation of real use-cases, monitoring memory consumption.
2x might be an overkill, esp if your app uses 8G under normal circumstances. Picking proper limitations is individual to each app

@leduyquang753 ever considered upgrading from java4?

@netikras docker is a fair point, but i dont see any reason on actual hardware

@ganjaman virtual machines -- memory baloon [overcommitted vmware's memory]. Rougue jvms could make the whole esx unstable.

Iron -- shared environments, oomk, memleaks that could be triggered by corner-case scenarios and capable to choke the whole os [assuming oomk is disabled]

desktop apps - ... It's quite obvious

overall it's better practice to run your apps in strictly controlled envs.

@ganjaman with oome you could at least get a heap dump triggered for post-mortem analysis. Oomk, dead os -- they leave you no such ability

@ganjaman it’s running in docker.