Replay's recorder captures non-deterministic behaviors in programs to ensure that when replayed, the behavior of interest—such as JavaScript state or DOM contents—remains consistent with the original recording, achieving effective rather than complete determinism. This approach allows for flexibility, as pointer values and certain runtime components like the garbage collector (GC) and just-in-time (JIT) compilers can vary during replay without affecting the overall behavior, enabling analyses and maintaining efficiency. While non-deterministic elements like malloc and runtime components introduce complexity, they allow analyses to be conducted during replaying that do not require reconfiguration during recording, thus reducing overhead and storage needs. However, adjustments are sometimes necessary to maintain consistency, such as ensuring hashtable iteration order remains unchanged despite varying pointer values. Handling exceptions in non-deterministic GC behavior, like leaking objects to avoid discrepancies in short recordings, is a current strategy, with plans to enforce deterministic finalizer execution for longer recordings.