debugging-strategies

Intermittent bugs require extensive logging of timing, state transitions, and external interactions to catch the failure condition. Look for race conditions in async code, then stress test by running the scenario many times with varied timing and load.

Use git bisect: mark the current commit as bad and a known working commit as good, then test each midpoint checkout Git presents. After each test, run git bisect good or bad until the exact regressing commit is identified.

Use the built-in breakpoint() function or pdb for interactive debugging, and ipdb for an enhanced interface. For performance issues, run cProfile and analyze results with pstats to find the slowest functions by cumulative time.

Monitor process.memoryUsage().heapUsed over time and generate heap snapshots with v8.writeHeapSnapshot() when usage grows abnormally. In Chrome DevTools, compare heap snapshots taken before and after an action to find retained objects.

Production-only bugs usually stem from environment differences: dependency versions, data volume, configuration, or user permissions. Gather evidence from error tracking and logs, then reproduce locally with anonymized production data and matching environment settings.

Use an interactive debugger when you need to inspect complex state, step through execution, or set conditional breakpoints without modifying code. Console logging suffices for simple value tracing but becomes noisy for deep call stacks or timing-sensitive issues.