如何修改Spring Batch事务隔离级别？附JobLauncher启动Job代码

Hey there! Let's break down how to adjust the transaction isolation level in Spring Batch based on your scenario. Here are the common approaches you can take:

Since you're using JobLauncher to start your job, you can customize its transaction behavior by setting a TransactionTemplate with your desired isolation level. This applies to the transaction that wraps the job startup process:

@RestController
public class SystemController {
    static Logger logger = LoggerFactory.getLogger(SystemController.class);
    JobExecution jobExecution;
    
    @Autowired
    JobLauncher jobLauncher;
    @Autowired
    Job job;

    // ... your existing request mapping

    // Define a custom JobLauncher bean with specified transaction isolation
    @Bean
    public JobLauncher customJobLauncher(JobRepository jobRepository, PlatformTransactionManager transactionManager) {
        SimpleJobLauncher jobLauncher = new SimpleJobLauncher();
        jobLauncher.setJobRepository(jobRepository);
        
        TransactionTemplate transactionTemplate = new TransactionTemplate(transactionManager);
        // Replace with your target isolation level
        transactionTemplate.setIsolationLevel(TransactionDefinition.ISOLATION_READ_COMMITTED);
        jobLauncher.setTransactionTemplate(transactionTemplate);
        
        return jobLauncher;
    }

    @Bean
    public PlatformTransactionManager transactionManager(DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }
}

If you need granular control (e.g., a specific step requires a different isolation level than others), you can configure the transaction attributes directly on the step:

@Bean
public Step myCustomStep(ItemReader<Data> reader, ItemProcessor<Data, Data> processor, 
                         ItemWriter<Data> writer, StepBuilderFactory stepBuilderFactory,
                         PlatformTransactionManager transactionManager) {
    return stepBuilderFactory.get("myCustomStep")
            .<Data, Data>chunk(10)
            .reader(reader)
            .processor(processor)
            .writer(writer)
            .transactionAttribute(customTransactionAttribute())
            .build();
}

private DefaultTransactionAttribute customTransactionAttribute() {
    DefaultTransactionAttribute attribute = new DefaultTransactionAttribute();
    // Use your desired isolation level here
    attribute.setIsolationLevel(TransactionDefinition.ISOLATION_REPEATABLE_READ);
    attribute.setPropagationBehavior(TransactionDefinition.PROPAGATION_REQUIRED);
    return attribute;
}

Spring Batch uses the JobRepository to store metadata like job executions and step executions. You can set the isolation level for these internal operations:

@Bean
public JobRepository jobRepository(DataSource dataSource, PlatformTransactionManager transactionManager) throws Exception {
    JobRepositoryFactoryBean factory = new JobRepositoryFactoryBean();
    factory.setDataSource(dataSource);
    factory.setTransactionManager(transactionManager);
    // Set isolation level for creating job execution records
    factory.setIsolationLevelForCreate("ISOLATION_SERIALIZABLE");
    factory.setTablePrefix("BATCH_"); // Match your batch table prefix if applicable
    return factory.getObject();
}

Available Isolation Levels #

You can use any of the standard Spring TransactionDefinition constants for isolation levels:

• TransactionDefinition.ISOLATION_DEFAULT: Uses the database's default isolation level
• TransactionDefinition.ISOLATION_READ_UNCOMMITTED
• TransactionDefinition.ISOLATION_READ_COMMITTED
• TransactionDefinition.ISOLATION_REPEATABLE_READ
• TransactionDefinition.ISOLATION_SERIALIZABLE

内容的提问来源于stack exchange，提问作者Naveen Kumar Mishra