Engineering notes
How things actually work — the mechanism, the defaults, and what they cost you. Written against primary sources and reviewed before publishing.
Spring Boot Interview Questions for Experienced Developers, Settled by Running Them
Seven Spring Boot questions senior interviews ask, answered with real output — starting with the @Transactional method that threw and still committed.
Backend & APIsJava 8 Stream API Interview Questions, With the Output to Prove It
Java 8 stream interview questions answered with output from JDK 8, 21 and 25, including a sorted() that did no work and a parallel reduce wrong every time.
JavaGit Interview Questions and Answers, Proved in a Terminal
Ten git interview questions answered with terminal output on git 2.50.1, from what a commit holds to why following git's own push hint undid a fix.
Cloud & DevOpsDockerfile Best Practices, Each One Built and Measured
Seven Dockerfile best practices, each measured: a 4.81s rebuild cut to 0.54s, a removed compiler still costing 240MB, and why exec form won't stop cleanly.
ContainersA Jenkins Pipeline Tutorial That Times Every Stage
A declarative pipeline built and run on Jenkins 2.568.3, with the per-stage numbers the tutorials leave out — including what a single sh step costs.
Cloud & DevOpsA Spring Cloud Gateway Example, Run Until Every Default Showed Itself
Spring Cloud Gateway 5.0.3 run for real: routes, timeouts, retries and a Redis rate limiter measured, plus the old property prefix it silently ignores.
Distributed SystemsMicroservices Interview Questions, Answered by Running Them
Seven microservices interview questions answered with counts from running Spring Boot services — starting with why three retries at three hops made 64 calls.
Distributed SystemsSQL Interview Questions for Experienced Engineers, Settled on Two Real Databases
The SQL questions experienced engineers get, run on PostgreSQL 17 and MySQL 8.4 — including a REPEATABLE READ that silently lost an update on one of them.
DatabasesJava Multithreading Interview Questions, Answered by Running Them
Six questions from every Java concurrency interview, answered with a program's output rather than a definition — starting with how much a race really loses.
Java