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0 pointsjshen9y ago0 comments

I have golang website/web app that runs at tens of megabytes per process. A very similar java web app runs in a few hundred megabytes per process.

I also run these in on cloud platforms that auto scale. The golang processes spin up very quickly, the java ones not so much.

In these two respects the JVM is heavy compared to golang for my very common scenarios. The heaviness also causes me to spend more money for the JVM solution.

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mike_hearn9y ago· 1 in thread

But what max heap size did you set for the JVM?

I have an app that people were complaining took too much memory. A quick look with VisualVM showed that its actual heap usage when idling was only 50 mb but because we hadn't set any heap size limit, it was reserving hundreds of megs from the OS. The idea is that it can run faster if it does that. The fix was simply to use the -Xmx option to tell it to use less memory and GC more often.

fauigerzigerk9y ago

The JVM is very inflexible in that respect. If you give it more memory it will keep all of it way beyond the point where it matters for performance. If you give it less memory you need to know exactly how much less you can give it before performance craters.

In other words, JVM deployments need a lot more tuning than Go and they will generally need a lot more memory as well. But you're right, not setting -Xmx at all will make the JVM look worse than it really is.

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