Add spring-batch: jobs, steps, chunk processing and restartability on Boot 4.1
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
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# spring-batch
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Companion code for **[Spring Batch on Boot 4.1: Jobs, Steps, Chunk Processing and Restartability](https://ankurm.com/)**
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on [ankurm.com](https://ankurm.com).
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Verified against Spring Boot **4.1.1**, Spring Batch **6.0.5**, Spring Framework **7.0.9**, on
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Temurin JDK **25.0.4.1+1**.
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One job (`productImportJob`: import a CSV of products, then report a count), configured three
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different ways by Spring profile, plus one infrastructure variant that is not a profile:
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| Profile / flag | What it demonstrates | Docs |
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|---|---|---|
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| `clean` | The happy path: chunk-oriented reading, filtering, writing | [ch. 3](docs/03-chunk-oriented-processing.md), [ch. 4](docs/04-item-processor-as-filter.md) |
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| `broken` | No fault tolerance: a bad row fails the whole chunk and the job; restart resumes exactly where it left off | [ch. 7](docs/07-restartability.md) |
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| `skip` | `faultTolerant().skip(...)`: the same bad row is skipped instead, job completes in one pass | [ch. 8](docs/08-skip-vs-restart.md) |
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| `--spring.autoconfigure.exclude=...BatchJdbcAutoConfiguration` | Resourceless job repository: a restart forgets everything happened | [ch. 10](docs/10-resourceless-vs-jdbc.md) |
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## Documentation chapters
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1. [The problem, and the smallest correct mental model](docs/01-the-problem-and-mental-model.md)
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2. [The anatomy of a job](docs/02-anatomy-of-a-job.md)
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3. [Chunk-oriented processing](docs/03-chunk-oriented-processing.md)
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4. [The item processor as a filter](docs/04-item-processor-as-filter.md)
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5. [Launching a job, and why restart is not a separate API](docs/05-launching-and-jobparameters.md)
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6. [The JDBC writer, and why it is not `beanMapped()`](docs/06-jdbc-writer-and-records.md)
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7. [Restartability: what actually resumes, and from where](docs/07-restartability.md)
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8. [Skip vs. restart](docs/08-skip-vs-restart.md)
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9. [Corrections found while writing this](docs/09-corrections.md)
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10. [Resourceless vs. JDBC-backed job repositories](docs/10-resourceless-vs-jdbc.md)
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11. [Production checklist](docs/11-production-checklist.md)
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## Captured output
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Everything under [`docs/output/`](docs/output) was produced by a real run and is quoted verbatim
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in the article and the chapters above:
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| File | What produced it |
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|---|---|
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| `01-processor-filter.txt`, `02-exception-hierarchy.txt` | JUnit tests, via `mvn test` |
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| `03-stepbuilder-chunk-overloads.txt`, `04-two-executioncontext-classes.txt`, `09-commandlinejobrunner-deprecated-not-removed.txt` | `javap` against the real 6.0.5 jars, via `scripts/capture-javap.sh` |
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| `05-happy-path.txt` | The `clean` profile, via `scripts/capture-scenarios.sh` |
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| `07-restart-run1-fails.txt`, `08-restart-run2-resumes.txt` | The `broken` profile, run twice in separate JVMs against the same database |
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| `10-skip-instead-of-fail.txt` | The `skip` profile |
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| `11-resourceless-forgets-everything.txt` | The `clean` profile with `BatchJdbcAutoConfiguration` excluded, run twice |
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## Running it
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Needs a JDK 25 and Maven 3.9.
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```bash
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export JAVA_HOME=/path/to/jdk-25
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mvn -DskipTests package
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./scripts/run-all.sh # regenerates everything under docs/output/
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```
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Or run one scenario by hand:
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```bash
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java -jar target/spring-batch-1.0.0.jar \
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--spring.profiles.active=clean \
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--import.file=file:./scenario-data/clean-demo/input.csv \
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--spring.datasource.url=jdbc:h2:file:./scenario-data/clean-demo/db
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```
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`scripts/run-scenario.sh <name> <profile> <source-csv>` wraps that for repeat use. Each scenario
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gets its own file-based H2 database under `scenario-data/<name>/`, gitignored, so runs never
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interfere with each other and a restart persists across separate `java -jar` invocations the way
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it would across a real process restart.
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There is a diagnostic-adjacent endpoint nowhere in this module by design — everything
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observable here comes from the standard `BATCH_STEP_EXECUTION` table via a plain SQL query,
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which is deliberately how [chapter 10](docs/10-resourceless-vs-jdbc.md) suggests checking your
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own job repository in production.
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