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

Suppose you have steps, A,B1,B2,B3,C. You want to run B1,B2 & B3 in parallel. You first need to create sub-flows for them and then add to one flow with SimpleAsyncTaskExecutor():

@Bean
public Job job()
{
    final Flow flowB1 = new FlowBuilder<Flow>("subflowb1").from(stepb1()).end();
    final Flow flowB2 = new FlowBuilder<Flow>("subflowb2").from(stepb2()).end();
    final Flow flowB3 = new FlowBuilder<Flow>("subflowb3").from(stepb3()).end();

    final Flow splitFlow = new FlowBuilder<Flow>("splitFlow")
        .start(flowB1)
        .split(new SimpleAsyncTaskExecutor())
        .add(flowB2, flowB3).build();

    return jobBuilderFactory
       .flow(stepA())
       .next(splitFlow)
       .next(stepC())
       .end()
       .build();
}