How to define parallel sub-flow in another flow in spring batch? - spring-batch

Question

I want to implement the flow structure as below in spring batch.
Job
/ \
Flow1 Flow2
/ \
Step1 Step2
/ / \
/ Step3 Flow3
/ \
/ Step4
\ /
\ /
\ /
Step5
The job configuration pseudo code is as below:
#Configuration
public class JobConfiguration {
......
#Bean
public Job Job() {
Flow flow1 = new FlowBuilder<SimpleFlow>("flow1")
.start(step1())
.build();
Flow flow2 = new FlowBuilder<SimpleFlow>("flow2")
.start(step2())
.next(step3())
.split(new SimpleAsyncTaskExecutor()).add(flow3)
.build();
Flow flow3 = new FlowBuilder<SimpleFlow>("flow3")
.start(step4())
.build();
return jobBuilderFactory.get("job")
.incrementer(new RunIdIncrementer())
.start(flow1)
.split(new SimpleAsyncTaskExecutor()).add(flow2)
.next(Step5())
.end()
.build();
}
......
}
When I run the batch, the log shows that step1, step2, step3 and step5 are executed, but step4 is not run.
I am wondering how to define sub-flow inside another flow, is the above code the right way to implement it?
Thanks in advance!

Answer 1

Running each flow in isolation shows that Flow1 and Flow3 are correct, but Flow2 isn't. Running only Flow2 with:
return jobBuilderFactory.get("job")
.incrementer(new RunIdIncrementer())
.start(flow2)
.build()
.build();
shows that step2 and step3 are executed, but not step4. So the problem is with the definition of this flow.
You need to define a parallel flow between Step3 and Flow3 as you did for Flow1 and Flow2. Here is an example:
#Bean
public Job Job() {
Flow flow1 = new FlowBuilder<SimpleFlow>("flow1")
.start(step1())
.build();
Flow flow3 = new FlowBuilder<SimpleFlow>("flow3")
.start(step4())
.build();
Flow parallelFlow = new FlowBuilder<SimpleFlow>("parallelFlow")
.start(step3())
.split(new SimpleAsyncTaskExecutor()).add(flow3)
.build();
Flow flow2 = new FlowBuilder<SimpleFlow>("flow2")
.start(step2())
.next(parallelFlow)
.build();
return jobs.get("job")
.incrementer(new RunIdIncrementer())
.start(flow1)
.split(new SimpleAsyncTaskExecutor()).add(flow2)
.next(step5())
.end()
.build();
}
Hope this helps.