This piece discusses the reliability of garbage collectors in the context of Whippet development, focusing on semi-space collectors and block-structured heaps. The simple semi-space collector is praised for its reliability and performance predictability, making it ideal for resource-constrained systems. However, the reliability of a copying collector with a block-structured heap is questioned due to non-commutative evacuation, leading to potential fragmentation issues. Multiple mutator threads also introduce unreliability, as the live object graph size is not always deterministic. The solution to mitigating fragmentation-related unreliability is to increase heap size. Embracing virtual memory and growable heaps is recommended for maintaining soft reliability.
https://wingolog.org/archives/2024/07/10/copying-collectors-with-block-structured-heaps-are-unreliable