java - Duplicate Spring Batch Job Instance

Question

I have a small sample Spring Batch application that when started for the first time will work fine but whenever I shut the application down & restart the jar I always get this error:

Caused by: org.springframework.dao.DuplicateKeyException: PreparedStatementCallback; SQL [INSERT into BATCH_JOB_INSTANCE(JOB_INSTANCE_ID, JOB_NAME, JOB_KEY, VERSION) values (?, ?, ?, ?)]; Duplicate entry '1' for key 1; nested exception is com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry '1' for key 1

I'm not sure if I have the job incrementer setup wrong. But like I said I can start it up & then use the web service url, /jobLauncher.html, to invoke the batch process any number of times just fine. It's only after I shutdown the application & restart it that I get this error. It wants to use id 1 for the job execution table but id 1 is already there from the previous runs.

Main class

@EnableAutoConfiguration
@ComponentScan
public class Application {

    public static void main(String[] args) throws Exception {
        SpringApplication.run(Application.class, new String[]{ "date=" + System.currentTimeMillis() });
    }
}

Webservice class

@Controller
public class JobLauncherController {

    @Autowired
    JobLauncher jobLauncher;

    @Autowired
    Job job;

    @RequestMapping("/jobLauncher.html")
    @ResponseBody
    public String handle() throws Exception{
        jobLauncher.run(job, new JobParametersBuilder().addString("date", System.currentTimeMillis() + "").toJobParameters());
        return "Started the batch...";
    }
}

Spring Batch class

@Configuration
@EnableBatchProcessing
public class SampleBatchApplication {

    @Autowired
    private JobBuilderFactory jobs;

    @Autowired
    private StepBuilderFactory steps;

    @Bean
    protected Tasklet tasklet() {
        return new Tasklet() {
            @Override
            public RepeatStatus execute(StepContribution contribution,
                                        ChunkContext context) {
                return RepeatStatus.FINISHED;
            }
        };
    }

    @Bean
    public Job job() throws Exception {
        return this.jobs.get("job")
                   .incrementer(new RunIdIncrementer())
                   .flow(this.step1())
                   .end()
                   .build();
    }

    @Bean
    protected Step step1() throws Exception {
        return this.steps.get("step1").tasklet(this.tasklet()).build();
    }

    @Bean
    public DataSource dataSource() {

        BasicDataSource ds = new BasicDataSource();

        try {
            ds.setDriverClassName("com.mysql.jdbc.Driver");
            ds.setUsername("test");
            ds.setPassword("test");
            ds.setUrl("jdbc:mysql://127.0.0.1:3306/spring-batch");

        } catch (Exception e) {
            e.printStackTrace();
        }
        return ds;
    }
}

Answer 1

Found the issue. When using the @EnableAutoConfiguration annotation from Spring Boot it will invoke the org.springframework.boot.autoconfigure.batch.BatchAutoConfiguration class which will initialize the database from the 'schema-mysql.sql' file.

Inside the schema-mysql.sql file is some code to reset the sequence id's for the batch meta tables which is why I was getting a duplicate key error:

INSERT INTO BATCH_STEP_EXECUTION_SEQ values(0);
INSERT INTO BATCH_JOB_EXECUTION_SEQ values(0);
INSERT INTO BATCH_JOB_SEQ values(0);

The fix was to build the Spring Batch tables separately & then change the @EnableAutoConfiguration annotation to:

@EnableAutoConfiguration(exclude={BatchAutoConfiguration.class})

so that when the application starts up it will not try to initialize the Spring Batch tables.

To exclude or customize Spring Boot's auto-configuration for other components you can find some docs here: http://projects.spring.io/spring-boot/docs/spring-boot-autoconfigure/README.html

The BatchAutoConfiguration code: https://github.com/spring-projects/spring-boot/blob/master/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/batch/BatchAutoConfiguration.java