Spring Batch : parallel steps execution in java configuration file

Question

I am trying to make a sample application on parallel step execution in java configuration file but get perplexed that how many files(job repository,job launcher and execution etc.) are being configured and initialized and if configured then how? Simply I need a sample application to clarify the basics of parallel execution of steps in a job.

Answer 1

Here's an example of using splits via java config. In this example, flows 1 and 2 will be executed in parallel:

@Configuration
public class BatchConfiguration {

    @Autowired
    private JobBuilderFactory jobBuilderFactory;

    @Autowired
    private StepBuilderFactory stepBuilderFactory;

    @Bean
    public Tasklet tasklet() {
        return new CountingTasklet();
    }

    @Bean
    public Flow flow1() {
        return new FlowBuilder<Flow>("flow1")
                .start(stepBuilderFactory.get("step1")
                        .tasklet(tasklet()).build())
                .build();
    }

    @Bean
    public Flow flow2() {
        return new FlowBuilder<Flow>("flow2")
                .start(stepBuilderFactory.get("step2")
                        .tasklet(tasklet()).build())
                .next(stepBuilderFactory.get("step3")
                        .tasklet(tasklet()).build())
                .build();
    }

    @Bean
    public Job job() {
        return jobBuilderFactory.get("job")
                .start(flow1())
                .split(new SimpleAsyncTaskExecutor()).add(flow2())
                .end()
                .build();
    }

    public static class CountingTasklet implements Tasklet {

        @Override
        public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
            System.out.println(String.format("%s has been executed on thread %s", chunkContext.getStepContext().getStepName(), Thread.currentThread().getName()));
            return RepeatStatus.FINISHED;
        }
    }
}