Production checklist

Last reviewed May 28, 2026 Content v20260528

Track mode: server_compiled
Means: Compiled runner
Reading: ~1 min
Level: advanced

This lesson

This lesson teaches Production checklist: the syntax, APIs, and habits you need before advancing in Java.

Teams ship Production checklist on every Java codebase—skipping it leaves gaps in debugging and code reviews.

You will apply Production checklist in contexts like: Spring Boot APIs, banking systems, Android (with Kotlin), and batch/data pipelines on the JVM.

Write Java with a public class (lessons use Main), click Run on server—the dev runner runs javac then java; fix compile errors from stderr (LEARNING_RUNNER_ENABLED=true).

When functions, arrays, and basic OOP from intermediate lessons are familiar.

Shipping Java services means more than passing tutorials: build reproducibility, observability, security, and JVM tuning matter in production.

Before deploy

Pin JDK version in CI and containers; use Maven/Gradle wrapper
Run unit + integration tests; static analysis (SpotBugs, Checkstyle)
Externalize config (env vars, Spring profiles)—no secrets in JARs
Health checks, structured logging (JSON), metrics (Micrometer/Prometheus)
Dependency scanning for CVEs; keep Spring Boot baseline updated

Runtime hygiene

Size heap and choose GC (G1 default on modern JDK); watch GC logs
Connection pool limits for JDBC; timeouts on HTTP clients
Graceful shutdown hooks; idempotent consumers for queues

Important interview questions and answers

Q: How do you debug OutOfMemoryError?
A: Heap dump, analyze dominators, fix leaks or increase heap; don't only restart.
Q: 12-factor for Java?
A: Config in environment, stateless processes, logs as streams, disposable containers.

Self-check

Where should database passwords live?
Why use connection pools instead of new Connection per request?

Interview tip Lesson completion confidence

Can you explain this lesson in 30 seconds without reading notes?

Self-reflection (saved on this device)

Not saved yet.

Playground

Runs on the configured server runner (dev: npm run runner with LEARNING_RUNNER_ENABLED=true). Output appears below the editor.

Code runner not available

Server runner is disabled. Set LEARNING_RUNNER_ENABLED=true and LEARNING_RUNNER_URL in .env (see .env.example).

Check yourself

Multiple choice — immediate feedback.

Discussion

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Heap tuning thought?
Logging framework pick?

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