Cron Scheduling Cron Expression Syntax | Expression | Schedule | |------------|----------| | | Every hour | | | Every 15 minutes | | | Weekdays at 9:00 AM | | | First day of month, midnight | | | Every 6 hours | Node.js (node-cron) With Distributed Locking (prevent duplicate runs) Spring @Scheduled (Java) Distributed Scheduling (ShedLock) Python (APScheduler) Anti-Patterns | Anti-Pattern | Fix | |--------------|-----| | Cron on multiple instances without locking | Use distributed lock (Redlock, ShedLock) | | Long-running cron blocks next run | Use job queue for heavy work | | No error handlin…