May 2026 — Uber Cadence: concise monthly summary focused on business value and technical achievements for the cadence repo. Key features delivered: - Scheduler Concurrency Control: Implemented a concurrency_limit for the CONCURRENT overlap policy, tracking in-flight workflows and enforcing the cap on create/update to improve stability and performance. Added tests around capacity handling and error propagation. - CLI/API concurrency_limit: Added --concurrency_limit flag to cadence schedule create and update commands with validation logic and unit tests; enables operators to cap parallelism when using CONCURRENT overlap policy. - Scheduler API and Reliability: Wired Schedule APIs through Thrift transport, introduced time/duration mappers, and added tests for API handlers and helpers; cron validation, idempotent pause handling, and improved error reporting for abnormal scheduler termination. - Cron validation at API layer: Added proactive cron expression validation on create/update to reject invalid or impossible schedules before triggering workflows. - Reliability and UX improvements: Made pause idempotent to avoid overwriting pause metadata when already paused; enhanced DescribeSchedule to surface meaningful errors when the scheduler workflow ends abnormally, instead of reporting ACTIVE. Major bugs fixed: - Cron validation prevents invalid/impossible cron expressions from causing silent failures or dead schedules. - Idempotent pause behavior avoids unintended state changes and unnecessary workflow restarts. - DescribeSchedule previously reported ACTIVE for failed/terminated schedulers; now returns a contextual InternalServiceError with the close status to aid diagnosis. Overall impact and accomplishments: - Significantly improved stability and predictability of scheduling under high load and complex overlap configurations. - Enabled operators to reliably cap concurrency, reducing resource contention and improving throughput. - Strengthened reliability and operability through API-level validations, better error signaling, and clearer diagnostics. Technologies/skills demonstrated: - Go, Thrift transport integration, and IDL submodule management. - Time and duration mapping between internal models and API types; cron library integration for validation. - Comprehensive unit testing across API layers, mapper/converter utilities, and workflow handlers. - Observability through tests and structured error messaging for scheduler failures.

April 2026 monthly summary: Delivered substantial improvements in reliability, observability, and governance across cadence-workflow/cadence and uber/cadence. Focused on business value through robust testing, enhanced monitoring, and clearer ownership. Key outcomes include a comprehensive fuzz testing regime for Cadence mappers and error handling, extensive scheduler observability, and formal maintainer governance updates. The work enabled safer mappings, deeper visibility into scheduling workflows, and streamlined project stewardship, driving uptime, faster debugging, and data-driven decision making.