The bug
Since 1.13, the RAM used by the server has increased drastically to reach more than 3 GB in 1.15.2 and higher when it is not limited by JVM default arguments (= put -Xmx8G
for example)!
For comparison, 1.12.2 uses only 500 MB of RAM!
This problem is apparently due to the DataFixerUpper introduced in 1.13.
How to test
Go to the "Installations" section of your Minecraft launcher.
Click on the three dots that appear when you hover over the profile you want to use for this test, and then click "Edit". If you don't already have a profile, create one!
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Select the version you want to test.
Download the server jar of the version you want to test.
Open the task manager of your operating system.
Launch the server with the following JVM arguments (for 8GB of RAM):
java -Xmx8G -Xms1024M -jar server.jar nogui
Observe the evolution of the RAM used by the server in the task manager.
Repeat for each version you want to test.
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Videos tests
Here are all the tests I did from 1.12.2 to 1.16 Pre-Release 2, on all stable versions of Minecraft.
I have allocated 8 GB of RAM each time so as not to restrict the server to too low a ceiling, which would not allow us to see the problem.
No other programs run on the PC (except Discord and my recording program).
I did the test on my two different machines and the results are the same.
Minecraft 1.12.2 (~450 MB) :
Minecraft 1.13.2 (~2.5 GB) :
Minecraft 1.14.4 (~2.9 GB) :
Minecraft 1.15.2 (~3.0 GB) :
Minecraft 1.16 Pre-Release 2 (~3.1 GB) :
We can also observe that with each new version, the CPU is used harder and harder, even after the game is fully loaded (especially in 1.16).
Note: This ticket is attached to MC-188163 which processes the client side.
Linked issues
is duplicated by
Attachments
Comments


Can confirm for 1.16.1

Can confirm for 20w27a

Can confirm for 1.19. VERY HIGH

Why is this bug not resolved? I think this would be very important and could get a lot of players for the new versions.

Performance issues can be quite difficult and complicated to fix. This report has been given a Mojang Priority of "Normal", so it will get fixed at some point.
If you haven't already, be sure to upvote the issue 🙂

Thy 🙂
Can confirm