something.go

func getFlags(desiredHeap int64) string {
	asKb := desiredHeap / units.KiB

	// the following is specific to OpenJ9 and is based on Aikar's flags:
	// https://aikar.co/2018/07/02/tuning-the-jvm-g1gc-garbage-collector-flags-for-minecraft/

	// The equivalent of -XX:G1NewSizePercent/-XX:G1MaxNewSizePercent in OpenJ9's gencon policy is -Xmns/-Xmnx.
	// We have to manually compute these values ourselves. By default, the gencon policy assumes 25% of Xms, which is
	// simply not sufficient for Minecraft (and Aikar can tell you).
	xmns := asKb / 2
	xmnx := asKb * 4 / 5

	memFlags := fmt.Sprintf("-Xms%dk -Xmx%dk -Xmns%dk -Xmnx%dk", asKb, asKb, xmns, xmnx)
	return fmt.Sprintf("java -Xtune:virtualized -XX:+UseContainerSupport -Xgc:dnssExpectedTimeRatioMaximum=3 -Xgc:scvNoAdaptiveTenure %s -jar paper.jar", memoryFlags)
}