Save on JDBC connections by using JdbcCursorItemReader or JdbcPagingItemReader - spring-batch

Question

In the spring batch project, I used JdbcCursorItemReader to read data to process them in parallel. I can run the batch locally without any problem.
I also heard that JdbcPagingItemReader is recommended for parallel processing against JdbcCursorItemReader, as cursor reader will hold the connection too long while paging reader can release connection once the page size is reached.
I then switched to JdbcPagingItemReader in step2, but out of surprise, I got the exception below when running locally.
Caused by: java.sql.SQLTransientConnectionException: HikariPool-1 -
Connection is not available, request timed out after 300001ms.
However, it seems the above exception occurs in step1 before the paging reader in step2 is executed, and that is the only change made. Please shed some light on why the exception is thrown and if it is good practice to use paging reader instead of cursor in parallel processing. Much appreciated your help!
The code snippet is pasted below:
#Bean
#StepScope
public Flow createParallelSubFlow() {
List<Flow> subFlowList = new ArrayList<>();
List<Stream> streamList;
try {
streamList = dataSourceConfig.streamMapper().
getStreamListByStatus(Constants.PENDING_STATUS_CD);
} catch (Exception e) {
}
streamList.forEach(stream -> {
long id = stream.getStreamId();
String flowName = "stream" + id + "_flow";
Flow subFlow = new FlowBuilder<Flow>(flowName)
.start(step1(id))
.next(step2(id))
.end();
subFlowList.add(subFlow);
});
return new FlowBuilder<Flow>("splitFlow").split(new SimpleAsyncTaskExecutor())
.add(subFlowList.toArray(new Flow[0])).build();
}
public Step step1(long id) {
return stepBuilderFactory.get("step1")
.<Domain, Domain>chunk(100)
.reader(reader1(id))
.writer(writer1())
.build();
}
//#StepScope
//#Bean
public Step step2(long id) {
return stepBuilderFactory.get("step2")
.<Domain, Domain>chunk(100)
.reader(cursorReader2(id))
.processor(processor2)
.writer(writer2())
.build();
}
public JdbcCursorItemReader<Domain> cursorReader2(Long id) {
return new JdbcCursorItemReaderBuilder<Domain>()
.dataSource(dataSourceConfig.dataSource())
.name("cursorReader")
.sql(Constants.QUERY_SQL)
.preparedStatementSetter(new PreparedStatementSetter() {
#Override
public void setValues(PreparedStatement ps) throws SQLException {
ps.setLong(1, id);
}})
.rowMapper(new RowMapper())
.build();
}
//Switch from cursorReader2 to pagingReader2 in step2
public JdbcPagingItemReader<Domain> pagingReader2(Long id) {
return new JdbcPagingItemReaderBuilder<Domain>()
.dataSource(dataSourceConfig.dataSource())
.name("pagingReader")
.queryProvider(queryProvider())
.parameterValues(parameterValues(id))
.rowMapper(new RowMapper())
.pageSize(100)
.build();
}
#Bean
public PagingQueryProvider queryProvider() {
SqlPagingQueryProviderFactoryBean providerFactory = new SqlPagingQueryProviderFactoryBean();
Map<String, Order> sortKeys = new HashMap<>(2);
sortKeys.put("ID", Order.ASCENDING);
providerFactory.setDataSource(dataSourceConfig.dataSource());
providerFactory.setSelectClause("SELECT Clause");
providerFactory.setFromClause("FROM Clause");
providerFactory.setWhereClause("WHERE Clause");
providerFactory.setSortKeys(sortKeys);
PagingQueryProvider pagingQueryProvider = null;
try {
pagingQueryProvider = providerFactory.getObject();
} catch (Exception e) {
logger.error("Failed to get PagingQueryProvider", e);
throw new RuntimeException("Failed to get PagingQueryProvider", e);
}
return pagingQueryProvider;
}
private Map<String, Object> parameterValues(Long id) {
Map<String, Object> parameterValues = new HashMap<>();
parameterValues.put("1", id);
return parameterValues;
}