Claude
b81af72bc3
Companion code for "Spring Batch on Boot 4.1: Jobs, Steps, Chunk Processing and Restartability". A productImportJob configured three ways by profile against a poisoned CSV row, run as real java -jar processes (not just JUnit) so the restart story is genuine: a chunk fails and rolls back, the process exits, a brand-new JVM against the same file-based H2 database resumes at the exact next unread row (READ_COUNT 20, not 60) and completes. Findings the build pins: - StepBuilder.chunk(int, PlatformTransactionManager) still compiles in Batch 6.0.5 but returns the legacy SimpleStepBuilder; chunk(int) returns the new ChunkOrientedStepBuilder, and only the latter is used here. - Two different ExecutionContext classes now exist in two different packages (infrastructure.item vs core.repository.persistence) with different shapes. - spring-boot-starter-batch alone gives a resourceless JobRepository that forgets every JobInstance the moment the JVM exits; spring-boot-starter- batch-jdbc is what makes the restart demo possible at all, demonstrated by excluding BatchJdbcAutoConfiguration and watching a "restart" collide with the previous run's own data instead of resuming it. - A migration-guide summary claiming CommandLineJobRunner was removed in 6.0 is wrong -- javap against the real jar shows @Deprecated(forRemoval=true), not removed. - RepeatStatus moved from core.repeat to infrastructure.repeat, caught by the compiler rather than by reading docs. 11 documentation chapters, 10 captured transcripts (unit tests, javap output, and real two-JVM scenario runs), all regenerated by scripts/run-all.sh. Fixed after push: three dead docs.spring.io links in the doc chapters (readersAndWriters/* and chunk-oriented-processing/*.html paths moved when Spring Batch 6 reorganized its reference docs; corrected to the current readers-and-writers/*, processor.html and chunk-oriented-processing.html paths, verified 200 via curl before committing). Co-Authored-By: Claude Sonnet 5 <[email protected]> Claude-Session: https://claude.ai/code/session_019DXsJ1zpikbA1MQJN6RqFA
spring-boot-demo
Companion code for the Spring Boot articles on ankurm.com.
One directory per article. Each is a self-contained Maven project with its own README.md,
numbered documentation chapters under docs/, and captured real output under docs/output/
that a single script regenerates. Every figure quoted in an article came out of one of those
files.
| Directory | Article | What it demonstrates |
|---|---|---|
actuator-in-production/ |
Spring Boot Actuator in Production | endpoint exposure defaults, securing Actuator, custom health indicators and how they hang |
spring-boot-startup-time/ |
Why Your Spring Boot App Takes 8 Seconds to Start | BufferingApplicationStartup, JFR startup events, self time vs total time, the classpath-scan tax, the JDK 25 AOT cache |
configuration-properties/ |
@ConfigurationProperties vs @Value in Spring Boot 4 | relaxed binding measured three ways, record constructor binding, validation, IDE metadata generation |
profiles-and-config/ |
Spring Boot Profiles Done Right | the precedence stack made visible, config trees and ConfigMaps, why a profile file loses to an environment variable |
spring-aop/ |
Spring AOP Explained | every pointcut designator with real matches, JDK vs CGLIB proxies, six aspects that do not fire |
docker-images/ |
Dockerizing Spring Boot 4: Layered Jars, Buildpacks, Distroless and Image Size Benchmarks | one service packaged nine ways and measured: size on disk and pushed, rebuild delta, startup, PID 1 and signals, jlink, the JDK 25 AOT cache |
kubernetes-deployment/ |
Deploying Spring Boot 4 on Kubernetes | probe groups under a dependency outage, graceful shutdown under load four ways, JVM ergonomics per pod shape, CPU limits throttling GC, HPA on a Micrometer metric |
problem-details/ |
Global Exception Handling with ProblemDetail (RFC 9457) in Spring Boot 4 | thirteen failures under five handling setups, validation errors, i18n, content negotiation, errors outside MVC, silent 500s, decoding on the client |
resilience/ |
Spring Framework 7's Built-in Resilience: @Retryable, @ConcurrencyLimit, and What's Left for Resilience4j | @Retryable and @ConcurrencyLimit counted invocation by invocation, retries inside transactions, where Resilience4j still earns its place, migrating from Spring Retry |
caching/ |
The Spring Cache Abstraction: @Cacheable, @CacheEvict, Key Generators and the Self-Invocation Trap | the self-invocation trap measured four ways, the key collision SimpleKeyGenerator makes easy, eviction timing under a thrown exception, a rollback the cache keeps, and where this sits next to Hibernate's L2 cache |
spring-batch/ |
Spring Batch on Boot 4.1: Jobs, Steps, Chunk Processing and Restartability | a job that fails mid-chunk and resumes exactly where it left off across two separate JVMs, skip vs. restart on the same poisoned row, the resourceless job repository that forgets a restart ever happened, and the chunk(int) vs chunk(int, tx) builder split |
Articles whose text is kept here rather than only on the blog have it under
<directory>/post/ — post.md for the body and meta.md for the title, excerpt and
categories.
Running any of them
Each project needs a JDK 25 and Maven 3.9. docker-images also needs Docker, and
kubernetes-deployment Docker plus a Kubernetes cluster; their READMEs list the rest:
cd <directory>
export JAVA_HOME=/path/to/jdk-25
mvn -DskipTests package
./scripts/run-all.sh # regenerate every transcript under docs/output/
Licence
MIT — see LICENSE.