Oilpan Compaction and Conservative Stack Scanning in Blink GC

Modern Blink’s Oilpan utilizes a mark-and-sweep garbage collection system, largely integrated within the V8 C++ library, to manage memory for web elements and container backings. While the system supports compaction to reduce fragmentation, this process is strictly atomic and only occurs when the native stack is guaranteed to be free of heap pointers. During active code execution, memory pressure can trigger emergency GCs via an allocation-retry path, but these cycles use conservative stack scanning to protect raw pointers. Because the collector cannot safely update unknown references on the stack, compaction is disabled during these mid-loop or emergency events. Consequently, while standard objects like DOM nodes remain stationary, certain container backings may move, but only at well-defined safepoints where the stack is empty. Developers must treat every allocation as a potential pause point while recognizing that out-of-memory states are often fatal rather than recoverable through nested collection tricks.