Month: 2026-01 — yuwata/systemd. Focused on improving reliability and observability of file descriptor set collection. Key feature delivered: FD Set Fill Diagnostics and Error Handling, introducing detailed debug logging in fdset_new_fill() to surface failures during FD collection. Major bugs fixed: replaced silent error paths with actionable logs via log_debug_errno, enabling visibility of the failing FD path (via fd_get_path) and its inode type. Overall impact: enhanced reliability during service startup and FD handling, with faster incident triage and increased maintainability. Technologies/skills demonstrated: C, /proc/self/fd access, fd_set handling, fcntl/fstat usage, and diagnostic logging (log_debug_errno). Business value: higher uptime, faster debugging, and clearer root-cause analysis for FD-related issues.