AIKIDO-2026-10943

TL;DR

The native io-event extension keeps worker thread references that can go stale when Ruby compacts the heap, leading to use-after-free if the pool later uses those pointers. Internal selector and array allocations used raw libc allocators with debug-only assert checks, so release builds could dereference NULL and crash the VM when memory is exhausted instead of raising an exception. The patch adds GC compaction callbacks, movable marking, write barriers for WorkerPool, and switches selector internals to Ruby's xmalloc family so allocation failure is handled safely.