Memory usage | Together Java | Page 1

quasi hatch Jul 26, 2023, 12:06 PM

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I've inherited a sub optimal performing application; so I'm trying to pinpoint why this app isn't as performant as thought.
The host/machine has 32GB of ram. The app has been started with -Xmx20480m (rougly 20GB)
Using htop I see the app has a VIRT memory of 21.7Gb and RES of ~16GB. This leads me to believe the app is using only ~16GB of the allocated memory, but is using 25GB of virtual memory; something I find very odd.

Does this mean it's swapping?
Why isn't it using the full 20GB?
How I can analyze this further?

static summitBOT Jul 26, 2023, 12:06 PM

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<@&987246964494204979> please have a look, thanks.

static summitBOT Jul 26, 2023, 12:06 PM

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static summit <@&987246964494204979> please have a look, thanks.

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empty heron Jul 26, 2023, 12:20 PM

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quasi hatch I've inherited a _sub optimal_ performing application; so I'm trying to pinpoint...

And what about SWAP in htop ?
Also does your host ram exceed 100%, then yes it would need to swap
Also, why did you said 25gb ?
Xmx is about java max heap size, so it doesn't take into account things like code, stack, etc, and also doesn't take into account native heap, since java has no control over it
If you want to see what is taking a lot in your app, you can use a profiler

lean pilot Jul 26, 2023, 12:53 PM

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Just to further clarify, VIRT includes all the memory a process might access which is reversed for your process so while your program is using 16GB, it can use upto 21GB

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Does this mean it's swapping?
No but you can use vmstat if you want to see the swap rates

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Why isn't it using the full 20GB?
The application probably does not use 20 GB (or things like GC are doing it's job)
How I can analyze this further?
A good profiler is Intellij's Java Profiler

#Memory usage