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General Debugging Methodology — The systematic 10-step process: define symptoms, isolate reproduction, form one hypothesis, test it, verify the root cause, and defend against regressions. Escalation guide: when to escalate from fmt.Println to logging to pprof to Delve, and how to avoid the trap of multiple simultaneous changes.
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Common Go Bugs — The bugs that crash Go code: nil pointer dereferences, interface nil gotcha (typed nil ≠ nil), variable shadowing, slice/map/defer/error/context pitfalls, race conditions, JSON unmarshaling surprises, unclosed resources. Each with reproduction patterns and fixes.
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Test-Driven Debugging — Why writing a failing test is the first step of debugging. Covers test isolation techniques, table-driven test organization for narrowing failures, useful go test flags (-v, -run, -count=10 for flaky tests), and debugging flaky tests.
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Concurrency Debugging — Race conditions, deadlocks, goroutine leaks. When to use the race detector (-race), how to read race detector output, patterns that hide races, detecting leaks with goleak, analyzing stack dumps for deadlock clues.
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Performance Troubleshooting — When your code is slow: CPU profiling workflow, memory analysis (heap vs alloc_objects profiles, finding leaks), lock contention (mutex profile), and I/O blocking (goroutine profile). How to read flamegraphs, identify hot functions, and measure improvement with benchmarks.
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pprof Reference — Complete pprof manual. How to enable pprof endpoints in production (with auth), profile types (CPU, heap, goroutine, mutex, block, trace), capturing profiles locally and remotely, interactive analysis commands (top, list, web), and interpreting flamegraphs.
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Diagnostic Tools — Auxiliary tools for specific symptoms. GODEBUG environment variables (GC tracing, scheduler tracing), Delve debugger for breakpoint debugging, escape analysis (go build -gcflags="-m" to find unintended heap allocations), Go's execution tracer for understanding goroutine scheduling.
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Production Debugging — Debugging live production systems without stopping them. Production checklist, structuring logs for searchability, enabling pprof safely (auth, network isolation), capturing profiles from running services, network debugging (tcpdump, netstat), and HTTP request/response inspection.
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Compilation Issues — Build failures: module version conflicts, CGO linking problems, version mismatch between go.mod and installed Go version, platform-specific build tags preventing cross-compilation.
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Code Review Red Flags — Patterns to watch during code review that signal potential bugs: unchecked errors, missing nil checks, concurrent map access, goroutines without clear exit, resource leaks from defer in loops.
