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πŸ“¦ Minecraft Modpack Profileβ˜• Java 21 Optimized

Optimal RAM for GregTech New Horizons (GTNH) & JVM Optimization Guide

The ultimate, ultra-realistic industrial progression modpack. GTNH features thousands of active machine blocks, complex multi-block structures, and tick-heavy chemical pipelines running 24/7, making memory bandwidth and stable CPU GC cycles vital.

Baseline Memory6 GB
Mod Count300 mods
Optimal GC EngineGenerational ZGC
Stutter RiskLow
300 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 CollectorGenerational ZGC
JVM Stutter / Pause Risk
CRITICAL (OS SWAP)

OS memory is choked. Hard disk pagefile swapping will cause heavy, multi-second gameplay freezing!

Minecraft Modpack presetJava 21 runtime active

Optimized JVM arguments console

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

-Xms8G -Xmx8G -XX:+UseZGC -XX:+ZGenerational -XX:+AlwaysPreTouch -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:+PerfDisableSharedMem
Generational ZGC (Concurrent Garbage Collector)

Performs memory cleanup concurrently with game loops. Pause times are consistently below 1ms, completely eliminating garbage-collection lag spikes and visual stutters.

βš™οΈ Requirements: Requires Java 21+ and a memory pool of 6GB or higher.
OS Memory Starvation Safeguard Engaged

E.g. You attempted to allocate 9GB of RAM on a 16GB PC.

Because Minecraft runs inside a virtual machine (JVM), the host operating system (Windows/macOS), graphics drivers, Discord, and Chrome require dedicated memory headroom to coordinate background tasks. Allocating more than 50% of system memory triggers intense disk paging (swap files), which freezes frame timings and locks your PC.

πŸ’‘ Solution: We have safely scaled back your JVM maximum size to 8GB (50% capacity cap).

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)

Is 6GB enough for GregTech New Horizons?β–Ό
Yes. Due to extreme optimization by the GTNH developer team, a solo early-game setup runs perfectly on 6GB. For massive, late-game industrial factories with thousands of active machines, we recommend allocating 8GB-10GB and using Java 21 with ZGC.
Why does GTNH support Java 21 if it runs on Minecraft 1.7.10?β–Ό
The GTNH developers have backported modern Java compatibility directly into their custom launcher and mod ecosystem, allowing players to leverage the massive performance benefits of Java 21 and Generational ZGC.