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Microsoft 的 TTD 與 Mozilla 的 RR

也是個在瀏覽器 tab 上放了一陣子的連結... 先前看到 MicrosoftTime Travel Debugger (TTD),可以錄下程式執行的狀態,然後回放與搜尋:「Thoughts On Microsoft's Time-Travel Debugger」,另外有 CppCon 2017 上的影片,在 YouTube 上:

另外 Mozilla 也有類似的工具,叫做 rr (在影片開頭就有人問類似的問題 XD),程式碼在 GitHub 上:「mozilla/rr」。

而 TTD 與 rr 兩者最大的差異當然是平台支援的情況:

The most important and obvious difference between TTD and rr is that TTD is for Windows and rr is for Linux (though a few crazy people have had success debugging Windows applications in Wine under rr).

但另外一個也很重要的差異是 TTD 支援完整的 multi-threading,這對於現代的程式來說還蠻常見的:

TTD supports recording of multiple threads in parallel, while rr is limited to a single core.


On the other hand, per-thread recording overhead seems to be much higher in TTD than in rr. It's hard to make a direct comparison, but a simple "start Firefox, display mozilla.org, shut down" test run on similar hardware takes about 250 seconds under TTD and 26 seconds under rr.