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Heap dumps find heap leaks. A growing process RSS with a stable heap is a different problem entirely — native memory, Metaspace, DirectByteBuffers, and JNI allocations that the standard tooling misses.
Read moreOptional is a return type that signals absence explicitly. It's not a null replacement, not a container to store in fields, and not a way to avoid NullPointerException everywhere. Used correctly, it improves API clarity. Used incorrectly, it adds allocation and verbosity without benefit.
Read moreStream intermediate operations do not execute until a terminal operation is called. This laziness enables short-circuiting, infinite streams, and fusion optimizations — and causes correctness bugs when side effects are assumed to have already fired.
Read moreCreating threads directly is expensive, uncontrolled, and hard to shut down cleanly. ExecutorService solves all three problems — but its default configurations have tradeoffs that matter in production.
Read moreHibernate generates SQL from your entity model and query methods. The generated SQL is often correct but rarely optimal. Understanding what gets generated — and the specific patterns that override it — determines whether JPA is a productivity tool or a performance liability.
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