Systems

Introduction Every software system—whether it’s a relational database, a distributed key‑value store, an operating system, or a simple file server—must contend with the possibility of unexpected failure. Power outages, hardware faults, kernel panics, and bugs can all cause a crash that abruptly terminates execution. When a crash occurs, the system’s state may be partially updated, leaving data structures inconsistent and potentially corrupting user data. Crash recovery is the discipline of detecting that a crash has happened, determining which operations were safely completed, and restoring the system to a correct state without losing committed work. In the era of cloud-native services and always‑on applications, robust crash recovery is not a luxury—it’s a baseline requirement for high availability and data integrity. ...

Introduction Thread pools are a foundational concurrency primitive used to execute units of work (tasks) using a fixed or managed set of threads. They improve performance by amortizing thread lifecycle costs, improve stability by bounding concurrency, and provide operational control via queueing, task rejection, prioritization, and metrics. Despite their ubiquity, thread pools are often misconfigured or misapplied, leading to oversubscription, latency spikes, deadlocks, or underutilization. This comprehensive guide covers how thread pools work, design dimensions and trade-offs, sizing formulas and tuning strategies, scheduling algorithms, instrumentation, and language-specific implementations with code examples. It is aimed at practitioners building high-throughput, low-latency systems, or anyone seeking a deep understanding of thread pool internals and best practices. ...