debugging

A profiler is not a neutral observer: sampling and instrumentation see different things, distort the program in different ways, and answer different questions. This lesson covers how each works, why CPU time and wall-clock time give opposite answers, and how to read a flame graph correctly, including the axis that means nothing and is misread constantly.

Reconciliation buys robustness and charges for it in a specific currency: nothing is ever definitely finished, commands succeed without meaning anything worked, and manual fixes are silently undone. This lesson covers the failures that come from the model rather than from bugs, how to debug them, and when the whole thing is the wrong tool.

Git's undo commands are notoriously confusing because they are usually memorised as recipes. Read against the object model they separate cleanly: each acts on a different one of the three places content lives. This lesson maps them, covers recovery from the accidents that feel unrecoverable, and states what genuinely cannot be undone.

Starting a goroutine is one keyword; stopping one is a design decision nothing forces you to make. A goroutine blocked forever is never collected and holds everything it references, which is the most common Go-specific bug. This lesson covers how leaks happen, the cancellation mechanism that prevents them, and how to detect the ones already there.

Dive into LangSmith, the developer platform for building and evaluating robust Large Language Model (LLM) applications. Learn how to trace execution paths, debug complex chains, and rigorously evaluate your LLM's performance to ensure reliability and quality.