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
A Spring Boot 4.1.1 module whose test suite is the evidence for the article: 20 tests
producing 22 transcripts under docs/output/, plus 12 documentation chapters.
Findings the build pins:
- @EnableCaching has no exposeProxy attribute; the widely-copied
@EnableCaching(exposeProxy = true) does not compile.
- Two methods sharing a cache name and an argument type share a key space, and one
silently serves the other's answers.
- The documented cache-provider detection order does not match CacheType's enum
order in 4.1.1: COUCHBASE before INFINISPAN, and CACHE2K before CAFFEINE.
- beforeInvocation = true is NOT deferred by TransactionAwareCacheManagerProxy on
7.0.9 - doEvict picks evictIfPresent, which the decorator does not intercept.
- Four of five invalid declarations start a clean context and throw at the first call.
- Caffeine on the classpath silently displaces the simple provider.
Companion code for "Spring Framework 7's Built-in Resilience: @Retryable,
@ConcurrencyLimit, and What's Left for Resilience4j". Every retry counted
by recording real invocations: defaults, backoff and jitter, timeout,
reactive and CompletableFuture returns, the concurrency limit's BLOCK and
REJECT policies, retries around transactions, composition with
Resilience4j 2.4.0, and the annotation API across 7.0.0-7.0.9.
Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01C3TETMrqVUWeFkNtz3Jbo3
Companion code for "Global Exception Handling with ProblemDetail (RFC 9457)
in Spring Boot 4". Thirteen failures under five handling setups (Boot
defaults, the Boot flag, a ResponseEntityExceptionHandler advice, advice
plus an ErrorController, a catch-all ordered first), validation errors,
i18n, content negotiation, Security's 401/403, silent 500s and decoding
on the client. 16 tests pin the behaviour.
Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01C3TETMrqVUWeFkNtz3Jbo3
Companion code for "Deploying Spring Boot 4 on Kubernetes: Probes, Graceful
Shutdown, Limits and JVM Ergonomics". A dependency outage under three
probe-group setups, a rolling restart under load four ways (three runs
each), the JVM's ergonomic choices for nine pod shapes, one GC-heavy load
under five CPU limits with throttling counters, and an HPA driven by a
Micrometer gauge through prometheus-adapter. Measured on k3s v1.36.4.
Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01C3TETMrqVUWeFkNtz3Jbo3
Companion code for "Dockerizing Spring Boot 4: Layered Jars, Buildpacks,
Distroless and Image Size Benchmarks". Fat jar on JDK and JRE, layered jar
on Debian, Alpine and distroless, jlink, the JDK 25 AOT cache, Paketo
buildpacks and Jib, each measured for size on disk and pushed, rebuild
delta, startup, user and shell. Also PID 1 and signal handling, the jdeps
module gap, AOT cache mismatches and buildpacks memory calculation.
Transcripts in docs/output/, regenerated by scripts/run-all.sh.
Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01C3TETMrqVUWeFkNtz3Jbo3
configuration-properties/ @ConfigurationProperties vs @Value on Spring Boot 4.1.1.
The relaxed-binding matrix is generated by binding each spelling rather than
transcribed, and re-checked against real processes -- the in-process probe was
wrong twice before it was right. Records the three findings that came out of it:
@Value does get relaxed resolution inside Spring Boot (Boot attaches
ConfigurationPropertySources), the configuration processor silently stops
generating metadata on JDK 23+ when declared as a plain dependency, and @Valid is
not what makes nested constraints run.
profiles-and-config/ Precedence, profiles, spring.config.import and config trees.
/precedence reports every source holding a property in rank order with file and
line, which turns "my profile file had no effect" into a two-line answer. Also
pins the counterintuitive one: an imported file outranks the file that imported it.
spring-aop/ Designators, proxy types, and aspects that do not fire.
One advice per supported designator so the reference table is generated from real
matches; all fourteen unsupported designators fed to the parser. Two corrections to
the reference documentation: unsupported designators throw
UnsupportedPointcutPrimitiveException (extends RuntimeException, not
IllegalArgumentException), and spring-boot-starter-aop was renamed to
spring-boot-starter-aspectj in Boot 4.
19 contract tests across the three modules, 15 captured transcripts, all regenerated
by scripts/run-all.sh. Verified on Spring Boot 4.1.1, Spring Framework 7.0.9,
JDK 25.0.4.1.
Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Gip4srpzMwjgoba6uEfbr5
Adds spring-boot-startup-time/, the companion project for BLOG-618: a runnable
Spring Boot 4.1.1 application on JDK 25 that installs BufferingApplicationStartup
and FlightRecorderApplicationStartup behind a system property, and a /diag/startup
endpoint that computes step self time -- the number /actuator/startup does not give
you and the one that names the actual culprits.
Captured under docs/output/: the step tree sorted both ways, the same startup as JFR
events, a +5000-class experiment putting 0.11 ms per scanned class on the classpath
scan tax, the silent truncation a 2048-step buffer performs, and JDK 25 AOT cache
timings (6.93 s to 4.82 s). Post body and metadata live in post/.
Moves the existing Actuator project into actuator-in-production/ so the repository
holds one directory per article; the root README is now an index.
Companion repository for the ankurm.com article. Every transcript in docs/output/
was produced by running this project; scripts/run-all.sh regenerates all of them.
Verified against Spring Boot 4.1.1 / Framework 7.0.9 / Security 7.1.1 /
Micrometer 1.17.1 / kafka-clients 4.2.1 on Temurin JDK 25.0.4.1+1.
Claude
asmhatre