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Implement a Simple GC for Your Mini-JVM

hard8/8

Understand JVM GC: G1 Regions, Remembered Sets, SATB BarriersNext

Language

Compiler

2.0s Limit 256MB

Implementation

Write a C program that adds mark-and-sweep GC to a mini-JVM.

Requirements:

Define a simple object structure with a mark bit and payload
Maintain a global list or array of allocated objects
Implement a mark function that starts from roots (operand stack + locals)
Implement a sweep function that frees unmarked objects
Implement a gc_collect function that runs mark then sweep
Print heap statistics before and after collection
Output must contain: GC, mark-and-sweep, heap, and mini-JVM

Why This Matters

Rooting the mark phase in the operand stack and local variable slots mirrors exactly what HotSpot's garbage collectors do when they treat active stack frames as GC roots before any region- or generation-specific logic runs. Building this simple mark-and-sweep collector on your mini-JVM is the same foundational step that preceded G1, ZGC, and every other production JVM collector historically.

Hints

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Validation Suite

main.c

Workspace 1.0