Multithreading with StoredProcedureItemReader - spring-batch

Question

Is it possible to have multiple threads with StoredProcedureItemReader? I have done multithreading with PageReader but not sure if it will work with StoredProcedureItemReader.
Below is the job configuration for using a StoredProcedureReader. I have wrapped the reader in Thread safe reader. I want to use ThreadPoolTaskExecutor but not able to figure out how I can do partition for each thread with the Stored procedure.
***#Configuration
public class SpPocJobConfigurationMT {
private DataSource dataSource;
/**
* The Job builder factory.
*/
private JobBuilderFactory jobBuilderFactory;
/**
* The Jdbc template.
*/
#Autowired
JdbcTemplate jdbcTemplate;
/**
* The Step builder factory.
*/
private StepBuilderFactory stepBuilderFactory;
#Autowired
private BillingRecordAuditRepository billingRecordAuditRepository;
#Autowired
private StagingMortgageDataTxnRepository stagingMortgageDataTxnRepository;
private SystemRepository systemRepository;
#Autowired
public SpPocJobConfigurationMT(JobBuilderFactory jobBuilderFactory, StepBuilderFactory stepBuilderFactory, SystemRepository systemRepository, DataSource dataSource) {
Assert.notNull(systemRepository, "SystemRepository cannot be null");
Assert.notNull(jobBuilderFactory, "JobBuilderFactory cannot be null");
Assert.notNull(stepBuilderFactory, "StepBuilderFactory cannot be null");
Assert.notNull(dataSource, "DataSource cannot be null");
this.jobBuilderFactory = jobBuilderFactory;
this.stepBuilderFactory = stepBuilderFactory;
this.systemRepository = systemRepository;
this.dataSource = dataSource;
}
#Bean
#Transactional
#Description(value = "")
public Job SpPocJobMT() throws Exception {
return jobBuilderFactory.get("spPocJobMT")
.start(spPocStepMT())
.build();
}
#Bean
public Step spPocStepMT() throws Exception {
return stepBuilderFactory.get("spPocStepMT")
.allowStartIfComplete(false)
.<StagingDataDto,StagingDataDto> chunk(20)
.reader(sybcSpReaderMT())
.processor(spPocProcessorMT())
.writer(spPocWriterMT())
// .taskExecutor(new ThreadPoolTaskExecutor ())
// .taskExecutor(new SimpleAsyncTaskExecutor())
.build();
}
#Bean
public SpPocWriter spPocWriterMT() {
return new SpPocWriter(this.billingRepository, this.stagingTxnRepository);
}
#Bean
public SpPocProcessor spPocProcessorMT() {
return new SpPocProcessor();
}
#Bean
#StepScope
public SynchronizedItemStreamReader sybcSpReaderMT() {
StoredProcedureItemReader reader = new StoredProcedureItemReader();
SqlParameter[] parameters = {new SqlParameter("#p_id", OracleTypes.NUMBER)
, new SqlOutParameter("#p_out_c1", OracleTypes.CURSOR)
, new SqlOutParameter("#p_out_c2", OracleTypes.CURSOR)
};
reader.setDataSource(dataSource);
reader.setProcedureName("SP_POC_FINAL");
reader.setRowMapper(new SPRowMapper());
reader.setRefCursorPosition(3);
reader.setPreparedStatementSetter(new MyItemPreparedStatementSetter());
reader.setParameters(parameters);
reader.setSaveState(false);
reader.setVerifyCursorPosition(false);
SynchronizedItemStreamReader synchronizedItemStreamReader = new SynchronizedItemStreamReader();
synchronizedItemStreamReader.setDelegate(reader);
return synchronizedItemStreamReader;
}
public class MyItemPreparedStatementSetter implements PreparedStatementSetter {
#Override
public void setValues(PreparedStatement ps) throws SQLException {
ps.setInt(1, 1);
((CallableStatement) ps).registerOutParameter(2, OracleTypes.CURSOR);
((CallableStatement) ps).registerOutParameter(3, OracleTypes.CURSOR);
}
}
}***

Answer 1

The StoredProcedureItemReader extends AbstractItemCountingItemStreamItemReader which is not thread-safe, please check its javadoc.
If you want to use the StoredProcedureItemReader in a multi-threaded step, you need to wrap it in a SynchronizedItemStreamReader or make it step-scoped.