Engineer Tang's Implementation Study Notes

May 19, 2026 · Operations

Beyond 'grep error': How WARN, INFO, and DEBUG Logs Reveal Production Root Causes

This article demonstrates why relying solely on ERROR logs misses critical production issues, using four real cases where WARN storms caused memory overflow, slow SQL queries hid in INFO logs, DEBUG-level serialization spiked CPU, and silent data loss appeared only in business count mismatches — teaching a systematic log-analysis approach for root-cause detection.