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Time travel debugging
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<h2 id="characteristics-supporting-bi-directional-travel">Characteristics supporting bi-directional travel</h2> <p>There are several characteristics that support the ability to move backwards as well as forwards in time. </p> <ul><li>Selecting a <a href="/facts/Purely_functional_programming/am3DcNAd">purely functional programming</a> language helps due to the self-contained nature of <a href="/facts/Pure_function/xveknjJ3">pure functions</a>. Pure functions have no <a href="/facts/Side_effect_(computer_science)/AU3GlLzG">side effects</a> and depend only on the information explicitly provided to the function, providing a repeatable, reliable, replayable path through the code.</li> <li>Languages and debuggers that enable <a href="/facts/Hot_swapping/Jn56Jw3h">hot swapping</a>, the ability to modify code as the code is running, provide some of the requirements necessary to rewind, and potentially rewrite execution.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a><a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a></li> <li>Tools based on the <a href="/facts/GNU_Debugger/nTs958uC">GNU debugger (GDB)</a>, available for compatible languages such as <a href="/facts/C_(programming_language)/Ky2No763">C</a>, <a href="/facts/C%2B%2B/Et0F2qn9">C++</a>, <a href="/facts/Go_(programming_language)/oWlsmAFJ">Go</a>, and <a href="/facts/Fortran/m1KqjcMU">Fortran</a> are capable of reverse debugging, but the effort significantly slows interaction.<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a></li></ul> <h2 id="time-traveling-debuggers">Time traveling debuggers</h2> <p>Examples of debuggers with the ability to step backwards: </p> <table><tbody><tr><th>Language</th><th>Debuggers</th></tr><tr><td><a href="/facts/C%2B%2B/Et0F2qn9">C++</a></td><td><a href="/facts/Rr_(debugging)/NGXWkhVl">rr</a> for x86 Linux, <a href="/facts/Undo_(company)/WdB0Apsa">Undo UDB</a> for <a href="/facts/Linux/9FvCKSTq">Linux</a><a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a></td></tr><tr><td><a href="/facts/R_(programming_language)/LSrkr8K8">R</a></td><td>provDebugR<a class="footnote-ref" id="fnref:10" href="#fn:10"><sup>10</sup></a></td></tr><tr><td><a href="/facts/Python_(Programming_Language)/YbuGqofa">Python</a></td><td>PyTrace<a class="footnote-ref" id="fnref:11" href="#fn:11"><sup>11</sup></a></td></tr><tr><td><a href="/facts/JavaScript/XhhIIEsl">JavaScript</a></td><td>Wallaby.js,<a class="footnote-ref" id="fnref:12" href="#fn:12"><sup>12</sup></a> Meiosis Tracer<a class="footnote-ref" id="fnref:13" href="#fn:13"><sup>13</sup></a></td></tr><tr><td><a href="/facts/C_Sharp_(programming_language)/UC2gxeyb">C#</a></td><td>RevDeBug</td></tr><tr><td><a href="/facts/Java_(programming_language)/9ScgFyAL">Java</a></td><td>RevDeBug for <a href="/facts/C_Sharp_(programming_language)/UC2gxeyb">C#</a> and <a href="/facts/Java_(programming_language)/9ScgFyAL">Java</a>,<a class="footnote-ref" id="fnref:14" href="#fn:14"><sup>14</sup></a> WhyLine for <a href="/facts/Java_(programming_language)/9ScgFyAL">Java</a>,<a class="footnote-ref" id="fnref:15" href="#fn:15"><sup>15</sup></a> <a href="/facts/Undo_(company)/WdB0Apsa">Undo UDB</a></td></tr><tr><td><a href="/facts/Elm_(programming_language)/TnQVYGn6">Elm</a></td><td><a href="/facts/Elm_(programming_language)/TnQVYGn6">Elm</a> Debugger, <a href="/facts/Elm_(programming_language)/TnQVYGn6">Elm</a> Reactor<a class="footnote-ref" id="fnref:16" href="#fn:16"><sup>16</sup></a></td></tr><tr><td><a href="/facts/OCaml/ThBGLND8">OCaml</a></td><td><a href="http://caml.inria.fr/pub/docs/manual-ocaml/debugger.html">ocamldebug</a></td></tr><tr><td><a href="/facts/Go_(programming_language)/oWlsmAFJ">Go</a></td><td><a href="/facts/Undo_(company)/WdB0Apsa">Undo UDB</a> for <a href="/facts/Linux/9FvCKSTq">Linux</a><a class="footnote-ref" id="fnref:17" href="#fn:17"><sup>17</sup></a></td></tr><tr><td><a href="/facts/Rust_(programming_language)/8JNMV19F">Rust</a></td><td><a href="/facts/Undo_(company)/WdB0Apsa">Undo UDB</a> for <a href="/facts/Linux/9FvCKSTq">Linux</a><a class="footnote-ref" id="fnref:18" href="#fn:18"><sup>18</sup></a></td></tr><tr><td>Windows Native</td><td><a href="/facts/Microsoft/nGIDDXdx">Microsoft</a> Time Travel Debugging (TTD) Tool<a class="footnote-ref" id="fnref:19" href="#fn:19"><sup>19</sup></a> for native Windows software (x86, x64, ARM, ARM64<a class="footnote-ref" id="fnref:20" href="#fn:20"><sup>20</sup></a>), eShard <a href="https://eshard.com/esreven">esReven</a> Full System Timeless Analysis for Windows<a class="footnote-ref" id="fnref:21" href="#fn:21"><sup>21</sup></a></td></tr><tr><td>Linux Native</td><td>eShard <a href="https://eshard.com/esreven">esReven</a> Full System Timeless Analysis for Linux<a class="footnote-ref" id="fnref:22" href="#fn:22"><sup>22</sup></a></td></tr></tbody></table> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Interactive_computing/gtzhk4sJ">Interactive computing</a></li> <li><a href="/facts/List_of_functional_programming_languages/XuWNoawk">List of purely functional programming languages</a></li> <li><a href="/facts/Record_and_replay_debugging/Hj5LvMLM">Record and replay debugging</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>"Time Travel Debugging in WinDbg Preview!". Debugging Tools for Windows. Retrieved 2018-05-08. <a href="https://blogs.msdn.microsoft.com/windbg/2017/09/25/time-travel-debugging-in-windbg-preview/" target="_blank">https://blogs.msdn.microsoft.com/windbg/2017/09/25/time-travel-debugging-in-windbg-preview/</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Telles, Matthew; Hsieh, Yuan (2001-04-01). The Science of Debugging. Coriolis Group Books. ISBN 9781576109175. <a href="9781576109175" target="_blank">9781576109175</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>"Reverse debugging, time travel debugging". undo.io. 9 January 2013. Retrieved 2018-05-08. <a href="https://undo.io/resources/whitepapers/reverse-debugging-whitepaper/#introducing-reverse-debugging" target="_blank">https://undo.io/resources/whitepapers/reverse-debugging-whitepaper/#introducing-reverse-debugging</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>"Interactive Debugging With Node.js - DZone Web Dev". dzone.com. Retrieved 2018-05-08. <a href="https://dzone.com/articles/interactive-debugging-with-nodejs" target="_blank">https://dzone.com/articles/interactive-debugging-with-nodejs</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>"Elm's Time Travelling Debugger". debug.elm-lang.org. Retrieved 2018-05-08. <a href="http://debug.elm-lang.org/" target="_blank">http://debug.elm-lang.org/</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>"interactive programming". elm-lang.org. Retrieved 2018-05-08. <a href="http://elm-lang.org/blog/interactive-programming" target="_blank">http://elm-lang.org/blog/interactive-programming</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>"Hot reloading and time travel debugging: what are they?". Code Cartoons. 2015-10-21. Retrieved 2018-05-08. <a href="https://code-cartoons.com/hot-reloading-and-time-travel-debugging-what-are-they-3c8ed2812f35" target="_blank">https://code-cartoons.com/hot-reloading-and-time-travel-debugging-what-are-they-3c8ed2812f35</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>"6 Things You Should Know About Time Travel Debugging". undo.io. 3 January 2015. Retrieved 2018-05-08. <a href="https://undo.io/resources/blog-articles/6-things-time-travel-debugging/" target="_blank">https://undo.io/resources/blog-articles/6-things-time-travel-debugging/</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>"UDB - Time Travel Debugger for C/C++". <a href="https://undo.io/udb/" target="_blank">https://undo.io/udb/</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> <li id="fn:10"><p>"ProvTools/provDebugR". github.com. 2018-07-31. Retrieved 2018-07-31. <a href="https://github.com/provTools/provDebugR" target="_blank">https://github.com/provTools/provDebugR</a> <a href="#fnref:10" class="footnote-back-ref">↩</a></p></li> <li id="fn:11"><p>"PyTrace Time Travel Debugger for Python". <a href="https://pytrace.com/" target="_blank">https://pytrace.com/</a> <a href="#fnref:11" class="footnote-back-ref">↩</a></p></li> <li id="fn:12"><p>"Wallaby.js Introduction: Time Travel Debugger". wallabyjs.com. Retrieved 2020-02-27. <a href="https://wallabyjs.com/docs/intro/time-travel-debugger.html" target="_blank">https://wallabyjs.com/docs/intro/time-travel-debugger.html</a> <a href="#fnref:12" class="footnote-back-ref">↩</a></p></li> <li id="fn:13"><p>Donut, Fox (2018-04-29). "You Don't Need Redux, MobX, RxJS, Cerebral". Fox Donut. Retrieved 2018-05-24. <a href="https://medium.com/@foxdonut00/you-dont-need-redux-mobx-rxjs-cerebral-6a735b150a02" target="_blank">https://medium.com/@foxdonut00/you-dont-need-redux-mobx-rxjs-cerebral-6a735b150a02</a> <a href="#fnref:13" class="footnote-back-ref">↩</a></p></li> <li id="fn:14"><p>"About RevDeBug". revdebug.com. Retrieved 2020-03-28. <a href="https://revdebug.com/doc/tutorial/5.6.0.0/Getting-Started/about-RevDeBug/" target="_blank">https://revdebug.com/doc/tutorial/5.6.0.0/Getting-Started/about-RevDeBug/</a> <a href="#fnref:14" class="footnote-back-ref">↩</a></p></li> <li id="fn:15"><p>"Whyline for Java". cs.cmu.edu. Retrieved 2021-01-21. <a href="https://www.cs.cmu.edu/~NatProg/whyline-java.html" target="_blank">https://www.cs.cmu.edu/~NatProg/whyline-java.html</a> <a href="#fnref:15" class="footnote-back-ref">↩</a></p></li> <li id="fn:16"><p>"time travel made easy". elm-lang.org. Retrieved 2018-05-08. <a href="http://elm-lang.org/blog/time-travel-made-easy" target="_blank">http://elm-lang.org/blog/time-travel-made-easy</a> <a href="#fnref:16" class="footnote-back-ref">↩</a></p></li> <li id="fn:17"><p>"Greg Law on Debugging, Record & Replay of Data, and Hyper-Observability". <a href="https://www.infoq.com/podcasts/debugging-record-replay-data" target="_blank">https://www.infoq.com/podcasts/debugging-record-replay-data</a> <a href="#fnref:17" class="footnote-back-ref">↩</a></p></li> <li id="fn:18"><p>"Greg Law on Debugging, Record & Replay of Data, and Hyper-Observability". <a href="https://www.infoq.com/podcasts/debugging-record-replay-data" target="_blank">https://www.infoq.com/podcasts/debugging-record-replay-data</a> <a href="#fnref:18" class="footnote-back-ref">↩</a></p></li> <li id="fn:19"><p>DOMARS. "Time Travel Debugging - Overview". docs.microsoft.com. Retrieved 2018-05-08. <a href="https://docs.microsoft.com/en-us/windows-hardware/drivers/debugger/time-travel-debugging-overview#what-is-time-travel-debugging" target="_blank">https://docs.microsoft.com/en-us/windows-hardware/drivers/debugger/time-travel-debugging-overview#what-is-time-travel-debugging</a> <a href="#fnref:19" class="footnote-back-ref">↩</a></p></li> <li id="fn:20"><p>"Get WinDbg Preview". Microsoft. <a href="https://www.microsoft.com/en-us/p/windbg-preview/9pgjgd53tn86?activetab=pivot:regionofsystemrequirementstab" target="_blank">https://www.microsoft.com/en-us/p/windbg-preview/9pgjgd53tn86?activetab=pivot:regionofsystemrequirementstab</a> <a href="#fnref:20" class="footnote-back-ref">↩</a></p></li> <li id="fn:21"><p>"Full System Timeless Analysis for Windows". <a href="https://eshard.com/esreven#windows" target="_blank">https://eshard.com/esreven#windows</a> <a href="#fnref:21" class="footnote-back-ref">↩</a></p></li> <li id="fn:22"><p>"Full System Timeless Analysis for Linux". <a href="https://eshard.com/esreven#linux" target="_blank">https://eshard.com/esreven#linux</a> <a href="#fnref:22" class="footnote-back-ref">↩</a></p></li> </ol>