Java and Spring problems explained from real failures
2 posts. All topics
Most Java problems in production look the same from the outside: the service gets slow, memory climbs, or requests start timing out. The causes are usually small settings or habits that nobody noticed until traffic arrived.
Each post here starts from a symptom, shows how to confirm the cause with the tools the JDK and Spring already give you, and then walks through the fixes and what each one costs.
You do not need to know the internals first. The basics are explained inside each post, in plain language, before the failure.
Posts on Java
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10 min read
HikariPool-1 Connection is not available: pool exhausted
Why a Java app hangs with Connection is not available errors under load, how leaked or hoarded connections cause it, and how to find and fix it.
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15 min read
N+1 query problem in Hibernate and JPA: find it and fix it
Why a Hibernate or JPA page that is fast in development takes 10 seconds in production, how lazy loading hides hundreds of queries, and how to fix it.