5 ms·

I've never heard about rr http://rr-project.org/ http://rr-project.org/), his tool to record program execution and debug it afterwards. The alleged 1.2x slowdow

by neves 11y ago

I've never heard about rr http://rr-project.org/ http://rr-project.org/), his tool to record program execution and debug it afterwards. The alleged 1.2x slowdown in execution is negligible. The ability to reverse in time is almost a nirvana. I'm sad I didn't have it when I used to program C++. Hope he succeeds in his new endeavor. We'd all win big. Does anyone knows of similar tools for Python and in-browser Javascript?

ninjaranter 11y ago
Re: Javascript - If you use the'redux' (http://redux.js.org/ http://redux.js.org/) framework you can get something like this (https://github.com/gaearon/redux-devtools-dock-monitor https://github.com/gaearon/redux-devtools-dock-monitor)
- jeswin 11y ago
  I understand you never claimed they are similar. But to be fair (and with due credit to redux for being a great framework), all redux does is save method call arguments in an array. rr is on a different scale altogether.
pgbovine 11y ago
the python case is interesting ... after all, the interpreter is just another binary executable. perhaps there's a way to write a layer above rr to "step" in Python code rather than the underlying C code. same with JS (Node.js) or any other language run-time.
ianbicking 11y ago
Python and in-browser Javascript are also programs, in theory rr covers the entirety? But I don't know what the ergonomics are like (e.g., how much will you see program activity in your platform that you don't care about, and how well can you see the activity in the code you are debugging?)
- roca 11y ago
  Yes, rr can record python and JS execution just fine, but the debugging experience is hopeless, since right now rr just gives you gdb. With an astounding tolerance for pain you can make progress by calling JS engine functions from gdb, but nobody wants that. This is fixable, however, and on my agenda.
xigency 11y ago
Sounds very similar Green Hills Software's TimeMachine for embedded applications.
- dingo_bat 11y ago
  TimeMachine needs a specialized hardware probe connected via JTAG, if I'm not mistaken. The probe is powerful enough to record everything (registers, operations, etc) in its memory without affecting the embedded device. Then you can replay the info however you want, in as much detail as you like. The feature here is more like software emulation, and it will really allow you to take the instruction pointer in reverse direction. Unlike TimeMachine which records in real time and let's you browse the recorded data as you wish, but after execution has occurred.
- yitchelle 11y ago
  My thoughts were very similar to yours. In 1992, when I started out in embedded on a Philips 8051 and debugging it was via an ICE and had direct visibility and control of the 8051. The ICE would be connected to a bonded out version of the 8051 and I was almost able to capture every single clock cycle of 8051's execution. When I hit a failure, I would just replay the trace and see what went wrong. It looks like the folks on the big machines have caught up :-)
  - ArkyBeagle 11y ago
    I had access to a Huntsville Microsystems ICe that used a bog-standard - non-bonded-out - 68008 in harness. I had scripting tools that would capture and replay all the registers to back the machine up. That HMI was a brilliant machine. It's really the last debug tool I ever used besides AVR, PIC and one ARM JTAG for doing BSP work.
cpeterso 11y ago
Mozilla is prototyping a feature called "WebReplay" to support reverse-debugging of JavaScript and DOM mutation: https://developer.mozilla.org/en-US/docs/Mozilla/Projects/WebReplay https://developer.mozilla.org/en-US/docs/Mozilla/Projects/We... https://bugzilla.mozilla.org/show_bug.cgi?id=1207696 https://bugzilla.mozilla.org/show_bug.cgi?id=1207696 It looks like Microsoft is implementing a similar time-travel feature in Chakra: https://github.com/Microsoft/ChakraCore/commits/TimeTravelDebugging https://github.com/Microsoft/ChakraCore/commits/TimeTravelDe...
StevePerkins 11y ago
If I'm understanding this correctly, then Java has had it for ages now via the "Chronon" debugger. It's the only reason why I pay for an IntelliJ Ultimate Edition license, since it comes bundled.
- microcolonel 11y ago
  There are other reversible debuggers, but even a mature one like Chronon has more overhead than this. 1.2x is basically nothing.
  - easytiger 11y ago
    Not if you have > 1 busy thread.
shimon 11y ago
If you're willing to accept things that compile to in-browser javascript, check out Elm's magical time-traveling debugger: http://debug.elm-lang.org/ http://debug.elm-lang.org/
jc4p 11y ago
For Python my coworker (and friend) Tom has a great project called timetravelpdb: http://everythingsysadmin.com/2014/04/time-travel-pdb.html http://everythingsysadmin.com/2014/04/time-travel-pdb.html explains a bit on it, the repo is https://github.com/TomOnTime/timetravelpdb https://github.com/TomOnTime/timetravelpdb Basically it's an extension of pdb that allows you to jump back and forth in time.
martindale 11y ago
I'm building something like this for in-browser Javascript, but in a larger context. We're not ready for public consumption yet, but: https://fabric.fm https://fabric.fm
- jamiecollinson 11y ago
  Interesting! Tried to subscribe but got an error: {"code":-5000}
reaktivo 11y ago
I was really impressed when finding out about Microsoft's Chakra JS engine Time travelling debugger[1], I think that's what you're looking for, haven't tried it myself though. [1] https://youtu.be/1bfDB3YPHFI?t=304 https://youtu.be/1bfDB3YPHFI?t=304
tolmasky 11y ago
No exactly the same thing but Tonic has similar capabilities using CRIU (checkpoint and restore in user space) for Javascript time traveling: http://blog.tonicdev.com/2015/09/10/time-traveling-in-node.js-notebooks.html http://blog.tonicdev.com/2015/09/10/time-traveling-in-node.j... It's an interesting different approach because it allows you to rewind the entire machine, so you can interact with interactions between different processes, etc (happy to answer questions, I am a dev on it)
mrdrozdov 11y ago
There is something similar in bpython called rewind. Run a few commands in the repl and then try `ctrl+r`.
mrdrozdov 11y ago
I wonder how it works. Assuming it must capture state at t=n, and somehow calculate the diff to get to t=n+1. Could theoretically pop diffs to get to any point in the past.
Zitrax 11y ago
Gdb has supported reverse debugging since 2009.
- deleted 11y ago
  [deleted]
- sfink 11y ago
  I've used it, and I've been using rr. gdb's reverse debugging was useful to me a few times, in extremely limited situations. I often do my initial runs under rr, just in case I might want to debug, because it's useful most of the time and it's not enough overhead to worry about. gdb's reverse debugging works after you narrow the range of interest down to a very small region, because otherwise its buffer will repeatedly overflow and it'll take ages.
pflanze 11y ago
Seems rr is using fork for its implementation. The first time I've seen this approach taken is in Ocaml's debugger.[1] [1] http://caml.inria.fr/pub/docs/manual-ocaml/debugger.html http://caml.inria.fr/pub/docs/manual-ocaml/debugger.html
easytiger 11y ago
Its not free, but there is http://undo-software.com/undodb/ http://undo-software.com/undodb/

by neves 11y ago

ninjaranter 11y ago

Re: Javascript - If you use the'redux' (http://redux.js.org/ http://redux.js.org/) framework you can get something like this (https://github.com/gaearon/redux-devtools-dock-monitor https://github.com/gaearon/redux-devtools-dock-monitor)

jeswin 11y ago
I understand you never claimed they are similar. But to be fair (and with due credit to redux for being a great framework), all redux does is save method call arguments in an array. rr is on a different scale altogether.

pgbovine 11y ago

the python case is interesting ... after all, the interpreter is just another binary executable. perhaps there's a way to write a layer above rr to "step" in Python code rather than the underlying C code. same with JS (Node.js) or any other language run-time.

ianbicking 11y ago

Python and in-browser Javascript are also programs, in theory rr covers the entirety? But I don't know what the ergonomics are like (e.g., how much will you see program activity in your platform that you don't care about, and how well can you see the activity in the code you are debugging?)

roca 11y ago
Yes, rr can record python and JS execution just fine, but the debugging experience is hopeless, since right now rr just gives you gdb. With an astounding tolerance for pain you can make progress by calling JS engine functions from gdb, but nobody wants that. This is fixable, however, and on my agenda.

xigency 11y ago

Sounds very similar Green Hills Software's TimeMachine for embedded applications.

dingo_bat 11y ago
TimeMachine needs a specialized hardware probe connected via JTAG, if I'm not mistaken. The probe is powerful enough to record everything (registers, operations, etc) in its memory without affecting the embedded device. Then you can replay the info however you want, in as much detail as you like. The feature here is more like software emulation, and it will really allow you to take the instruction pointer in reverse direction. Unlike TimeMachine which records in real time and let's you browse the recorded data as you wish, but after execution has occurred.
yitchelle 11y ago
My thoughts were very similar to yours. In 1992, when I started out in embedded on a Philips 8051 and debugging it was via an ICE and had direct visibility and control of the 8051. The ICE would be connected to a bonded out version of the 8051 and I was almost able to capture every single clock cycle of 8051's execution. When I hit a failure, I would just replay the trace and see what went wrong. It looks like the folks on the big machines have caught up :-)
- ArkyBeagle 11y ago
  I had access to a Huntsville Microsystems ICe that used a bog-standard - non-bonded-out - 68008 in harness. I had scripting tools that would capture and replay all the registers to back the machine up. That HMI was a brilliant machine. It's really the last debug tool I ever used besides AVR, PIC and one ARM JTAG for doing BSP work.

cpeterso 11y ago

Mozilla is prototyping a feature called "WebReplay" to support reverse-debugging of JavaScript and DOM mutation: https://developer.mozilla.org/en-US/docs/Mozilla/Projects/WebReplay https://developer.mozilla.org/en-US/docs/Mozilla/Projects/We... https://bugzilla.mozilla.org/show_bug.cgi?id=1207696 https://bugzilla.mozilla.org/show_bug.cgi?id=1207696 It looks like Microsoft is implementing a similar time-travel feature in Chakra: https://github.com/Microsoft/ChakraCore/commits/TimeTravelDebugging https://github.com/Microsoft/ChakraCore/commits/TimeTravelDe...

StevePerkins 11y ago

If I'm understanding this correctly, then Java has had it for ages now via the "Chronon" debugger. It's the only reason why I pay for an IntelliJ Ultimate Edition license, since it comes bundled.

microcolonel 11y ago
There are other reversible debuggers, but even a mature one like Chronon has more overhead than this. 1.2x is basically nothing.
- easytiger 11y ago
  Not if you have > 1 busy thread.

shimon 11y ago

If you're willing to accept things that compile to in-browser javascript, check out Elm's magical time-traveling debugger: http://debug.elm-lang.org/ http://debug.elm-lang.org/

jc4p 11y ago

For Python my coworker (and friend) Tom has a great project called timetravelpdb: http://everythingsysadmin.com/2014/04/time-travel-pdb.html http://everythingsysadmin.com/2014/04/time-travel-pdb.html explains a bit on it, the repo is https://github.com/TomOnTime/timetravelpdb https://github.com/TomOnTime/timetravelpdb Basically it's an extension of pdb that allows you to jump back and forth in time.

martindale 11y ago

I'm building something like this for in-browser Javascript, but in a larger context. We're not ready for public consumption yet, but: https://fabric.fm https://fabric.fm

jamiecollinson 11y ago
Interesting! Tried to subscribe but got an error: {"code":-5000}

reaktivo 11y ago

I was really impressed when finding out about Microsoft's Chakra JS engine Time travelling debugger[1], I think that's what you're looking for, haven't tried it myself though. [1] https://youtu.be/1bfDB3YPHFI?t=304 https://youtu.be/1bfDB3YPHFI?t=304

tolmasky 11y ago

No exactly the same thing but Tonic has similar capabilities using CRIU (checkpoint and restore in user space) for Javascript time traveling: http://blog.tonicdev.com/2015/09/10/time-traveling-in-node.js-notebooks.html http://blog.tonicdev.com/2015/09/10/time-traveling-in-node.j... It's an interesting different approach because it allows you to rewind the entire machine, so you can interact with interactions between different processes, etc (happy to answer questions, I am a dev on it)

mrdrozdov 11y ago

There is something similar in bpython called rewind. Run a few commands in the repl and then try `ctrl+r`.

mrdrozdov 11y ago

I wonder how it works. Assuming it must capture state at t=n, and somehow calculate the diff to get to t=n+1. Could theoretically pop diffs to get to any point in the past.

Zitrax 11y ago

Gdb has supported reverse debugging since 2009.

deleted 11y ago
[deleted]
sfink 11y ago
I've used it, and I've been using rr. gdb's reverse debugging was useful to me a few times, in extremely limited situations. I often do my initial runs under rr, just in case I might want to debug, because it's useful most of the time and it's not enough overhead to worry about. gdb's reverse debugging works after you narrow the range of interest down to a very small region, because otherwise its buffer will repeatedly overflow and it'll take ages.

pflanze 11y ago

Seems rr is using fork for its implementation. The first time I've seen this approach taken is in Ocaml's debugger.[1] [1] http://caml.inria.fr/pub/docs/manual-ocaml/debugger.html http://caml.inria.fr/pub/docs/manual-ocaml/debugger.html

easytiger 11y ago

Its not free, but there is http://undo-software.com/undodb/ http://undo-software.com/undodb/