configure this:

@Bean
public TaskExecutor taskExecutor() {
    return new SimpleAsyncTaskExecutor("spring_batch");
}

@Bean
public Step sampleStep(TaskExecutor taskExecutor, JobRepository jobRepository, PlatformTransactionManager transactionManager) {
    return new StepBuilder("sampleStep", jobRepository)
                .<String, String>chunk(10, transactionManager)
                .reader(itemReader())
                .writer(itemWriter())
                .taskExecutor(taskExecutor)
                .build();
}

check out for this documentation : https://docs.spring.io/spring-batch/reference/scalability.html