Only growth heaps are allowed to start major GCs. Before this patch, growth heaps are defined as size pools that freed more slots than had empty slots (i.e. there were more dead objects that empty space).
But if the size pool is relatively stable and tightly packed with mostly old objects and has allocatable pages, then it would be incorrectly classified as a growth heap and trigger major GC. But since it's stable, it would not use any of the allocatable pages and forever be classified as a growth heap, causing major GC thrashing. This commit changes the definition of growth heap to require that the size pool to have no allocatable pages.
Added by peterzhu2118 (Peter Zhu) over 3 years ago
Fix major GC thrashing
Only growth heaps are allowed to start major GCs. Before this patch,
growth heaps are defined as size pools that freed more slots than had
empty slots (i.e. there were more dead objects that empty space).
But if the size pool is relatively stable and tightly packed with mostly
old objects and has allocatable pages, then it would be incorrectly
classified as a growth heap and trigger major GC. But since it's stable,
it would not use any of the allocatable pages and forever be classified
as a growth heap, causing major GC thrashing. This commit changes the
definition of growth heap to require that the size pool to have no
allocatable pages.