A conversation with StackAI's CTO: how Temporal cut indexing failures from 20% to below 0.1%

StackAI migrated their file indexing pipeline from Celery to Temporal Cloud, achieving a reduction in indexing failures from 20% to below 0.1%. This involved making each stage of the pipeline (download, extraction, chunking, indexing) durable with Temporal Workflows. They implemented granular retry logic, only retrying failed stages and avoiding redundant work. Parsing was extracted into a separate service using child workflows and durable waits with webhook callbacks for external parsers. Debugging was improved via the Temporal UI, and horizontal scaling was achieved by separating I/O-heavy and memory-heavy workloads into different worker fleets and task queues. Task priorities and durable timers were used to manage bursty workloads.