How does Ruby Garbage Collector (GC) decide when to run?

Ruby GC runs based on heap allocation thresholds and memory pressure heuristics.

CRuby uses a generational GC (minor and major collections). Objects are allocated in the young generation. When allocation thresholds are exceeded, a minor GC runs. If survivors accumulate or memory pressure increases, major GC is triggered. Incremental marking reduces pause times by spreading work across execution.