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📦 Minecraft Modpack Profile☕ Java 17 Optimized

Optimal RAM for RLCraft & JVM Optimization Guide

The legendary hyper-realistic survival fantasy modpack. RLCraft features hundreds of active, memory-intensive entity scripts, complex physics engines, and expansive dungeons that generate on the fly, putting immense pressure on CPU garbage collection.

Baseline Memory6 GB
Mod Count125 mods
Optimal GC EngineGenerational ZGC
Stutter RiskLow
125 Mods
Vanilla (0)Small (50)Medium (150)Heavy (300)Extreme (450+)
12 Chunks
Short (4)Normal (12)Far (18)Extreme (32)

Memory Allocation Map

8GB JVM
8GB Available
allocated to JVM Free for Operating System
Recommended allocation8 GB
Garbage CollectorG1GC
JVM Stutter / Pause Risk
MODERATE (GC SPIKE)

Large heap pool running G1GC will periodically trigger Stop-The-World sweeps, stalling FPS for 100ms+.

Minecraft Modpack presetJava 17 runtime active

Optimized JVM arguments console

Pre-configured garbage collection bounds synchronized to your sizer metrics.

-Xms8G -Xmx8G -XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:+AlwaysPreTouch -XX:G1NewSizePercent=30 -XX:G1MaxNewSizePercent=40 -XX:G1HeapRegionSize=8M -XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 -XX:G1MixedGCCountTarget=4 -XX:InitiatingHeapOccupancyPercent=15 -XX:G1MixedGCLiveThresholdPercent=90 -XX:G1RSetUpdatingPauseTimePercent=5 -XX:SurvivorRatio=32 -XX:+PerfDisableSharedMem -XX:MaxTenuringThreshold=1
Optimized G1GC (Garbage-First Collector)

Uses highly tuned sizing percentages and short garbage collection windows (MaxGCPauseMillis=200). Works perfectly for legacy clients or memory pools under 6GB.

⚙️ Requirements: Compatible with Java 8, 17, and 21. Optimal for low-overhead setups.

Minecraft Out-of-Memory (OOM) Crash Registry

Common crash signatures that indicate your Java heap allocations are failing.

Exit Code -1073740791System Starvation Crash

Occurs when Windows runs completely out of physical system memory and forcibly kills the Java VM. Triggered by over-allocating RAM inside launchers or running out of pagefile space.

OutOfMemoryErrorJVM Heap Exhaustion

Occurs when Minecraft Modpack registries baked items exceed allocated heap size. The internal JVM throws a "Java heap space" exception and shuts down safely. Solve by scaling up allocation slider.

GC Overhead Limit ExceededGarbage Collection Thrashing

Occurs when the JVM spends more than 98% of CPU time performing garbage collection loops but frees less than 2% of the heap. This causes intense stuttering before crashing. Check JVM arguments.

Frequently Asked Questions (FAQ)

What is the standard RAM allocation for RLCraft?▼
We recommend allocating exactly 6GB of RAM. RLCraft runs on an older Minecraft version (1.12.2) which is highly CPU-bound, making 6GB the perfect balance between asset caching and garbage collection speed.
Why does RLCraft stutter when I generate new chunks?▼
New chunk generation in RLCraft spawns complex structural designs and dense foliage. This creates a massive surge in garbage objects, causing lag spikes if you are using unoptimized JVM arguments.