Thanks for the reply, Dave! I will try to post one or two concrete use cases about the TraceDebugger in the next couple of days, so stay tuned. :-)
Best,
Christoph
---
Sent from Squeak Inbox Talk
On 2023-12-29T11:01:10-06:00, lewis@mail.msen.com wrote:
> This sounds like really interesting work! I love the idea of being
> able to interactively go back in "oops, I‘ve stepped too far, let‘s
> start all over again" situations. It will probably take some time for
> me and others to wrap our heads around the things you have done, so
> don't be surprised if you get a delayed response to this announcement
> :-)
>
> Congratulations!
> Dave
>
>
> On Fri, Dec 29 2023 at 01:42:16 AM +0100,
> christoph.thiede(a)student.hpi.uni-potsdam.de wrote:
> > Hi all!
> >
> > I‘m very excited to announce a project today that we have been
> > working on over the past two years: The *TraceDebugger* [1] is a new
> > back-in-time/time-travel/omniscient debugging tool for Squeak that
> > allows you to record past method activations and states during
> > execution and explore them later.
> >
> > <https://github.com/hpi-swa-lab/squeak-tracedebugger>
> >
> > Metacellonew
> > baseline:'TraceDebugger';
> > repository:'github://hpi-swa-lab/squeak-tracedebugger';
> > /"repository:
> > 'github://hpi-swa-lab/squeak-tracedebugger:squeak60';"//"for Squeak
> > 6.0"/
> > get;
> > load.
> >
> > **What can it do? (Features)**
> >
> > - *Record all method activations and historic states:* Normally step
> > through a program in the debugger while automatically recording its
> > execution.
> > - *Replay execution of a traced program:* Navigate through all
> > method invocations using the /*context tree*/ or the /*Step Back/Step
> > Forward*/ buttons (to avoid these "oops, I‘ve stepped too far,
> > let‘s start all over again" situations).
> > - *Interact with historic states:* Inspect/explore snapshots of
> > objects or send them any message.
> > - *State-centric debugging using the ***/History Explorer*/**:*
> > Gather, explore, and visualize all changes to an object/expression
> > over the recorded time ("When did this variable/collection/screenshot
> > change?").
> > - *Additional navigation tools* for searching and filtering the
> > context tree.
> > - *Focus on interactivity:* No hours of recording, no GBs of mem
> > consumption - at least for common small to medium programs.
> > - *UI resembles the classic Smalltalk debugger:* You'll find your
> > familiar stepping buttons, code browsing tools, inspectors, and
> > shortcuts - plus more.
> >
> > The TraceDebugger is a general-purpose tool and not tied to
> > particular domains. In the past months, we have successfully used it
> > to understand several bugs and interaction patterns in the Trunk
> > (Morphic layout/rendering, compiler/decompiler, code simulation,
> > …). The tool is also self-supporting, so you can debug a
> > TraceDebugger from another TraceDebugger. :-)
> >
> > **What can‘t it do (yet)? (Limitations and future work)**
> >
> > - *High performance:* While (sufficiently) fast enough for most
> > small to medium workloads, tracing very compute- or mem-intensive
> > operations may require more time (ex.: compiler/decompiler
> > invocation: <1s, HTTPS request: <10s, tool building: <5m, complex
> > rendering: minutes up to hours).
> > - *Not a dataflow analyzer:* The TraceDebugger does not track
> > dataflow events (e.g., argument passing) but only state changes.
> > - *No tracing of external states/events* for FFI/OSProcess or custom
> > VM modules.
> > - *No support for advanced language concepts* such as identity
> > forwarding/write barriers.
> >
> > **How does it work? (Implementation)**
> >
> > In one sentence: To record message sends and side effects, we
> > decorate the execution of certain bytecodes with tracing extensions
> > by modifying the code simulation using SimulationStudio [2].
> >
> > In one paragraph: The program is executed in a specialized code
> > simulator that overrides instructions for sending messages (e.g.,
> > send, superSend) and for performing side-effects (e.g., popIntoRcvr,
> > primitiveAtPut, push). All message sends are recorded in a tree and
> > all changed object slots are stored in a sparse time-dependent memory
> > structure before they are overwritten. For time-traveling, the tree
> > is traversed using a cursor. For accessing historic objects, a proxy
> > evaluates all messages sent to an object in another specialized
> > simulator (retracing simulator) that emulates historic states for the
> > requested point in time by forwarding read primitives (e.g.,
> > pushRcvr, primitiveAt) to the recorded memory. For gathering state
> > changes in the History Explorer efficiently, the query is evaluated
> > in a range retracing simulator with vectorization and fork semantics.
> >
> > In academic terms: We have published two papers about the
> > TraceDebugger that provide further details about its implementation
> > and its applications for program exploration, "Object-Centric
> > Time-Travel Debugging: Exploring Traces of Objects" [3] and
> > "Time-Awareness in Object Exploration Tools: Toward In Situ
> > Omniscient Debugging" [4].
> >
> > In Smalltalk: Just check out the code base and explore it by
> > yourself! The class comments in TraceDebugger <code://TraceDebugger>
> > and TDBCursor <code://TDBCursor> should provide good starting points.
> >
> > **How can I use it?**
> >
> > Please try it out and report feedback! The TraceDebugger supports
> > the latest Squeak Trunk and Squeak 6.0. You can either download a
> > prepared all-in-one bundle on GitHub:
> >
> > <https://github.com/hpi-swa-lab/squeak-tracedebugger/releases>
> >
> > Or you can install it into your own image using Metacello:
> >
> > Metacellonew
> > baseline:'TraceDebugger';
> > repository:'github://hpi-swa-lab/squeak-tracedebugger';
> > /"repository:
> > 'github://hpi-swa-lab/squeak-tracedebugger:squeak60';"//"for Squeak
> > 6.0"/
> > get;
> > load.
> >
> > To get started, just open a normal debugger (e.g., by selecting an
> > expression and pressing Cmd+Shift+D to debug it) and then press the
> > "Trace It" button on the right. There‘s also some pretty detailed
> > documentation in the Help Browser <code:// TraceDebugger showHelp>
> > that covers everything you should know.
> >
> > My goal is to improve convenience and provide a useful tool for the
> > community, so I‘m very excited to hear your impressions, ideas, and
> > thoughts. Here, on GitHub, or in a private message. Let‘s have a
> > great discussion! :-)
> >
> > Best,
> >
> > Christoph (and Marcel)
> >
> > PS: Props to Eliot who brought up the original idea of "subclassing
> > from Context" for other reasons four years ago. [5]
> >
> > [1] <https://github.com/hpi-swa-lab/squeak-tracedebugger>
> > [2] <https://github.com/LinqLover/SimulationStudio>
> > [3] Christoph Thiede, Marcel Taeumel, and Robert Hirschfeld. 2023.
> > Object-Centric Time-Travel Debugging: Exploring Traces of Objects.
> > <https://doi.org/10.1145/3594671.3594678> In /Companion Proceedings
> > of the 7th International Conference on the Art, Science, and
> > Engineering of Programming/ (/<Programming>'23 Companion/), March
> > 13–17, 2023, Tokyo, Japan. ACM, New York, NY, USA, 7 pages. DOI:
> > 10.1145/3594671.3594678 <https://doi.org/10.1145/3594671.3594678>.
> > PDF: <https://dl.acm.org/doi/pdf/10.1145/3594671.3594678>
> > [4] Christoph Thiede, Marcel Taeumel, and Robert Hirschfeld. 2023.
> > Time-Awareness in Object Exploration Tools: Toward In Situ Omniscient
> > Debugging. <https://dl.acm.org/doi/10.1145/3622758.3622892> In
> > /Proceedings of the 2023 ACM SIGPLAN International Symposium on New
> > Ideas, New Paradigms, and Reflections on Programming and Software/
> > (/Onward! '23/), October 25–27, 2023, Cascais, Portugal. ACM, New
> > York, NY, USA, 14 pages. DOI: 10.1145/3622758.3622892
> > <https://doi.org/10.1145/3622758.3622892>. PDF:
> > <https://dl.acm.org/doi/pdf/10.1145/3622758.3622892>
> > [5]
> > <http://lists.squeakfoundation.org/pipermail/squeak-dev/2019-October/204803.html>
> >
> > ---
> > /Sent from//Squeak Inbox Talk
> > <https://github.com/hpi-swa-lab/squeak-inbox-talk>/