ITPUB
Sep 15, 2026 · Backend Development
Thread Pool Tuning for 10M SMS/Hour: From Golden Formula to Backpressure
This article dissects a real interview challenge: designing a thread pool to send 10 million SMS messages in one hour. It explains why Executors is dangerous, how to calculate initial thread counts using the golden formula for I/O-bound tasks, why dynamic tuning with monitoring matters, and how CallerRunsPolicy provides natural backpressure in batch scenarios. It also covers reliability patterns like persistence, acknowledgments, and compensation tasks to prevent data loss on crashes.
BackpressureCallerRunsPolicyThread Pool
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