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Debugging

Document status35 - Reviewed

Debugging is the process of identifying, diagnosing, and resolving defects (bugs) within a software system. It is a critical part of the software development lifecycle and plays a key role in ensuring product quality and reliability.

Effective debugging requires a structured and methodical approach, combined with a solid understanding of the system, codebase, and expected behavior. Rather than simply fixing symptoms, the objective is to locate and resolve the root cause of a problem to prevent it from recurring.

When investigating an issue, apply a combination of the following practices:

1. Analyze Logs​

  • Review available application logs, system logs, or monitoring data to trace the origin of the problem.
  • Look for error messages, stack traces, or unusual patterns that might explain the failure.
  • If the existing logs lack sufficient detail, add targeted logging statements in relevant parts of the code to capture critical information about execution flow, variable values, and conditions.

2. Use a Debugger​

  • Attach a debugger to the running process or execute the code in debug mode.
  • Step through the code line by line to observe program flow and identify the exact line or operation causing the failure.
  • Inspect the state of the application at runtime - including variable values, object states, and call stacks - to determine why and under what conditions the issue arises.

3. Reproduce the Issue Consistently​

  • Work towards consistently reproducing the bug under controlled conditions.
  • Document the exact steps or inputs required to trigger the issue, to ensure it can be reliably investigated by others.
  • Once the problem is understood, capture the scenario in an automated test to prevent regressions in future changes.

Best Practices​

Applying these principles can make debugging more efficient and reliable:

  • Isolate the Problem Area
    Narrow down the scope by disabling unrelated features or modules to focus on the part of the system where the issue likely originates.

  • Work from Known-Good States
    Confirm that your environment, dependencies, and build artifacts are in a clean and consistent state. This reduces noise and avoids chasing unrelated issues.

  • Make Incremental Changes
    Apply only one change at a time and verify the result. Large or simultaneous changes make it difficult to understand which action resolved or affected the issue.

  • Keep Detailed Notes
    Document your findings, attempted fixes, and observations. This creates a useful audit trail and prevents repeating the same investigation steps.

  • Collaborate When Stuck
    If progress stalls, seek a fresh perspective from a teammate. Explaining the problem to someone else often helps uncover overlooked assumptions or details.

  • Validate the Fix Thoroughly
    After resolving the issue, verify that it does not introduce new failures or regressions by running the full test suite and performing targeted exploratory testing.