This article introduces incremental garbage collection (GC) which has been introduced in Ruby 2.2. We call this algorithm RincGC. RincGC achieves shor

Incremental Garbage Collection in Ruby 2.2

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2024-09-28 14:00:04

This article introduces incremental garbage collection (GC) which has been introduced in Ruby 2.2. We call this algorithm RincGC. RincGC achieves short GC pause times compared to Ruby 2.1.

About the Author: Koichi Sasada works for Heroku along with Nobu and Matz on C Ruby core. Previously he wrote YARV Ruby's virtual machine, and he introduced generational GC (RgenGC) to Ruby 2.1. Koichi wrote incremental GC for Ruby 2.2 and authored this paper.

Ruby uses GC to collect unused objects automatically. Thanks to GC, Ruby programmers do not need to release objects manually, and do not need to worry about bugs from object releasing.

The first version of Ruby already has a GC using mark and sweep (M&S) algorithm. M&S is one of the most simple GC algorithms which consists of two phases:

(1) Mark: traverse all living objects and mark as "living object". (2) Sweep: garbage collect unmarked objects as they are unused.