Styjun

I am trying to load set of csv file into mysql using spring batch.
My code is given below. But when I run with 2 or 3 files the data is loading fine. but when I try with 100 or more Its trowing an execption aftre loading 4 to 8 files data.
Exception:

ERROR 11633 --- [ main] o.s.batch.core.step.AbstractStep : Encountered an error executing step masterStep in job importUserJob
org.springframework.batch.core.JobExecutionException: Partition handler returned an unsuccessful step
 at org.springframework.batch.core.partition.support.PartitionStep.doExecute(PartitionStep.java:112) ~[spring-batch-core-4.0.1.RELEASE.jar!/:4.0.1.RELEASE]
 at org.springframework.batch.core.step.AbstractStep.execute(AbstractStep.java:200) ~[spring-batch-core-4.0.1.RELEASE.jar!/:4.0.1.RELEASE]
 at org.springframework.batch.core.job.SimpleStepHandler.handleStep(SimpleStepHandler.java:148) [spring-batch-core-4.0.1.RELEASE.jar!/:4.0.1.RELEASE]
 at org.springframework.batch.core.job.flow.JobFlowExecutor.executeStep(JobFlowExecutor.java:66) [spring-batch-core-4.0.1.RELEASE.jar!/:4.0.1.RELEASE]
 at org.springframework.batch.core.job.flow.support.state.StepState.handle(StepState.java:67) [spring-batch-core-4.0.1.RELEASE.jar!/:4.0.1.RELEASE]
 at org.springframework.batch.core.job.flow.support.SimpleFlow.resume(SimpleFlow.java:169) [spring-batch-core-4.0.1.RELEASE.jar!/:4.0.1.RELEASE]
 at org.springframework.batch.core.job.flow.support.SimpleFlow.start(SimpleFlow.java:144) [spring-batch-core-4.0.1.RELEASE.jar!/:4.0.1.RELEASE]
 at org.springframework.batch.core.job.flow.FlowJob.doExecute(FlowJob.java:136) [spring-batch-core-4.0.1.RELEASE.jar!/:4.0.1.RELEASE]
 at org.springframework.batch.core.job.AbstractJob.execute(AbstractJob.java:308) [spring-batch-core-4.0.1.RELEASE.jar!/:4.0.1.RELEASE]
 at org.springframework.batch.core.launch.support.SimpleJobLauncher$1.run(SimpleJobLauncher.java:141) [spring-batch-core-4.0.1.RELEASE.jar!/:4.0.1.RELEASE]
 at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:50) [spring-core-5.0.5.RELEASE.jar!/:5.0.5.RELEASE]
 at org.springframework.batch.core.launch.support.SimpleJobLauncher.run(SimpleJobLauncher.java:134) [spring-batch-core-4.0.1.RELEASE.jar!/:4.0.1.RELEASE]
 at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.execute(JobLauncherCommandLineRunner.java:163) [spring-boot-autoconfigure-2.0.1.RELEASE.jar!/:2.0.1.RELEASE]
 at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.executeLocalJobs(JobLauncherCommandLineRunner.java:179) [spring-boot-autoconfigure-2.0.1.RELEASE.jar!/:2.0.1.RELEASE]
 at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.launchJobFromProperties(JobLauncherCommandLineRunner.java:134) [spring-boot-autoconfigure-2.0.1.RELEASE.jar!/:2.0.1.RELEASE]
 at org.springframework.boot.autoconfigure.batch.JobLauncherCommandLineRunner.run(JobLauncherCommandLineRunner.java:128) [spring-boot-autoconfigure-2.0.1.RELEASE.jar!/:2.0.1.RELEASE]
 at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:797) [spring-boot-2.0.1.RELEASE.jar!/:2.0.1.RELEASE]
 at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:781) [spring-boot-2.0.1.RELEASE.jar!/:2.0.1.RELEASE]
 at org.springframework.boot.SpringApplication.run(SpringApplication.java:335) [spring-boot-2.0.1.RELEASE.jar!/:2.0.1.RELEASE]
 at org.springframework.boot.builder.SpringApplicationBuilder.run(SpringApplicationBuilder.java:137) [spring-boot-2.0.1.RELEASE.jar!/:2.0.1.RELEASE]

I don't know whats happening behind, Any help appreciated.
Code:

@Configuration
@EnableBatchProcessing
public class ImportJobConfig 

 @Autowired
 private JobBuilderFactory jobBuilderFactory;
 @Autowired
 private StepBuilderFactory stepBuilderFactory;
 @Autowired
 private DataSource dataSource;
 @Autowired
 private JdbcBatchItemWriter<Person> writer;
 @Autowired
 private FlatFileItemReader<Person> personItemReader;
 @Bean
 public DataSource dataSource() 
 final DriverManagerDataSource dataSource = new DriverManagerDataSource();
 dataSource.setDriverClassName("com.mysql.jdbc.Driver");
 dataSource.setUrl("URL");
 dataSource.setUsername("USERNAME");
 dataSource.setPassword("PASSWORD");
 return dataSource;
 
 @Bean
 public ThreadPoolTaskExecutor taskExecutor() 
 ThreadPoolTaskExecutor taskExecutor = new ThreadPoolTaskExecutor();
 taskExecutor.setMaxPoolSize(4);
 taskExecutor.setCorePoolSize(4);
 taskExecutor.setQueueCapacity(4);
 taskExecutor.afterPropertiesSet();
 taskExecutor.setAllowCoreThreadTimeOut(true);
 return taskExecutor;
 
 @Bean
 @Qualifier("masterStep")
 public Step masterStep() 
 return stepBuilderFactory.get("masterStep").partitioner("step1", partitioner()).step(step1())
 .taskExecutor(taskExecutor()).build();
 
 @Bean("partitioner")
 @StepScope
 public Partitioner partitioner() 
 System.out.println("In Partitioner");
 MultiResourcePartitioner partitioner = new MultiResourcePartitioner();
 ResourcePatternResolver resolver = new PathMatchingResourcePatternResolver();
 String filePath = "//data//person//*.csv";
 Resource[] resources = null;
 try 
 resources = resolver.getResources("file:" + filePath);
 catch (IOException e) 
 e.printStackTrace();
 
 partitioner.setResources(resources);
 partitioner.partition(4);
 return partitioner;
 
 @Bean
 public APSUploadFileItemProcessor processor() 
 return new APSUploadFileItemProcessor();
 
 @Bean
 public JdbcBatchItemWriter<Person> writer() 
 JdbcBatchItemWriter<Person> writer = new JdbcBatchItemWriter<>();
 try 
 writer.setItemSqlParameterSourceProvider(new BeanPropertyItemSqlParameterSourceProvider<Person>());
 writer.setSql("INSERT INTO person(name,business,phone) VALUES(name, :business, :phone)");
 writer.setDataSource(dataSource);
 catch (Exception e) 
 e.printStackTrace();
 
 return writer;
 
 @Bean
 public Job importUserJob(JobCompletionNotificationListener listener, Step step1) 
 return jobBuilderFactory.get("importUserJob").incrementer(new RunIdIncrementer()).listener(listener)
 .flow(masterStep()).end().build();
 
 @Bean
 public Step step1() 
 return stepBuilderFactory.get("step1").<Person, Person>chunk(10000).processor(processor())
 .writer(writer).reader(personItemReader).build();
 
 @Bean
 @StepScope
 @Qualifier("personItemReader")
 @DependsOn("partitioner")
 public FlatFileItemReader<Person> personItemReader(
 @Value("#stepExecutionContext['fileName']") String filename) throws MalformedURLException ")
 .names(new String[] "name","business","phone" )
 .fieldSetMapper(new BeanWrapperFieldSetMapper<Person>() 
 
 setTargetType(Person.class);
 
 ).resource(new UrlResource(filename)).build();