UndoDB is unique in that it is able to record with low overheads and without restriction on CPU make/model, execution environment (e.g. AWS), and comes with a host of features, including support for shared memory, deferred recording, live reversible debugging, attaching to a running process, and many more.
No. UndoDB can be used from various frontends e.g. Emacs, Eclipse, DDD or from the command line. This means UndoDB can be integrated into your developers’ existing workflow, making it quick and easy to get up and running.
UndoDB works on any Linux distro with kernel 2.6 or later, on ARM or x86. UndoDB also supports Android (Native) on ARM.
The number of lines of source is not directly relevant to UndoDB. Instead, it’s the size of the resulting program and its data that matters. We have customers that use UndoDB on programs that consume more than 100GB of memory.
No – UndoDB is for user-mode code only.
During record mode, the effects of all non-deterministic operations, including all system calls, thread-switches, signals and shared memory accesses, are stored in an event log. During replay, non-deterministic events are not performed directly, but their effects are synthesized based on the contents of the event log.
Yes. However, when debugging using traditional tools, it’s often necessary to restart the program multiple times. UndoDB saves time because you can go backward and forward as often as you need without having to restart. For a further speedup it’s possible to defer the start of recording until later in the program’s execution.
No, replaying process is self-contained and does not re-execute system calls. From outside (except via the debugger), the process appears to have frozen at the moment the recording stopped.
No, you can’t go back in time to change history. The reason is that in replay mode your application is disconnected from the outside world. Consider a webserver sending a page on a socket. If you go back to mid-way through the page’s transmission, change something and attempt to begin a new recording from that point, the webserver would send the second half of the page twice, very likely confusing the other end of the socket.
No - UndoDB is licensed under a proprietary license.
UndoDB invokes either a separately installed version of GDB or an “aggregated” version of GDB and interacts with it via GDB’s documented interfaces (namely GDB’s Python API and Remote Serial Protocol). UndoDB does not modify, link to, or exchange complex internal data structures with GDB, and does not form a combined work with GDB.
For reasons of convenience and stability the UndoDB release distribution includes a version of GDB in object code form in an “aggregate”. This version of GDB is conveyed in accordance with section 6 of version 3 of the GNU General Public License.
Undo has received confirmation from the Free Software Foundation that it is compliant with the terms of the GPL.