The features and general approach are quite similar. There are some significant internal differences. UndoDB relies on code instrumentation but rr does not. Ma

The features and general approach are quite similar. There are some significant internal differences. UndoDB relies on code instrumentation but rr does not. Mainly because of that (AFAIK), UndoDB's recording overhead is significantly higher than rr's. On the other hand, UndoDB can handle some cases rr does not, in particular when a recorded task shares memory with another task which is not part of the recording. Also, UndoDB supports ARM/Android and rr does not.