Spring batch ItemProcessor order of processing the items - spring

Question

Here is my spring configuration file.
<batch:job id="empTxnJob">
<batch:step id="stepOne">
<batch:partition partitioner="partitioner" step="worker" handler="partitionHandler" />
</batch:step>
</batch:job>
<bean id="asyncTaskExecutor" class="org.springframework.core.task.SimpleAsyncTaskExecutor" />
<bean id="partitionHandler" class="org.springframework.batch.core.partition.support.TaskExecutorPartitionHandler" scope="step">
<property name="taskExecutor" ref="asyncTaskExecutor" />
<property name="step" ref="worker" />
<property name="gridSize" value="${batch.gridsize}" />
</bean>
<bean id="partitioner" class="com.spring.mybatch.EmpTxnRangePartitioner">
<property name="empTxnDAO" ref="empTxnDAO" />
</bean>
<batch:step id="worker">
<batch:tasklet transaction-manager="transactionManager">
<batch:chunk reader="databaseReader" writer="databaseWriter" commit-interval="25" processor="itemProcessor">
</batch:chunk>
</batch:tasklet>
</batch:step>
<bean name="databaseReader" class="org.springframework.batch.item.database.JdbcCursorItemReader" scope="step">
<property name="dataSource" ref="dataSource" />
<property name="sql">
<value>
<![CDATA[
select *
from
emp_txn
where
emp_txn_id >= #{stepExecutionContext['minValue']}
and
emp_txn_id <= #{stepExecutionContext['maxValue']}
]]>
</value>
</property>
<property name="rowMapper">
<bean class="com.spring.mybatch.EmpTxnRowMapper" />
</property>
<property name="verifyCursorPosition" value="false" />
</bean>
<bean id="databaseWriter" class="org.springframework.batch.item.database.JdbcBatchItemWriter">
<property name="dataSource" ref="dataSource" />
<property name="sql">
<value><![CDATA[update emp_txn set txn_status=:txnStatus where emp_txn_id=:empTxnId]]></value>
</property>
<property name="itemSqlParameterSourceProvider">
<bean class="org.springframework.batch.item.database.BeanPropertyItemSqlParameterSourceProvider" />
</property>
</bean>
<bean id="itemProcessor" class="org.springframework.batch.item.support.CompositeItemProcessor" scope="step">
<property name="delegates">
<list>
<ref bean="processor1" />
<ref bean="processor2" />
</list>
</property>
</bean>
My custom range partitioner will split it based on primary key of emp_txn records.
Assume that an emp(primary key - emp_id) can have multiple emp_txn(primary key - emp_txn_id) to be processed. With my current setup, Its possible in ItemProcessor(either processor1 or processor 2) that 2 threads can process the emp_txn for same employee(i.e., for same emp_id).
Unfortunately the back end logic that process(in processor2) the emp_txn is not capable of handling transactions for same emp in parallel. Is there a way in spring batch to control the order of such processing?

Answer 1

With the use case you are describing, I think you're partitioning by the wrong thing. I'd partition by emp instead of emp-txn. That would group the emp-txns and you could order them there. It would also prevent the risk of emp-txns from being processed out of order based on which thread gets to it first.
To answer your direct question, no. There is no way to order items going through processors in separate threads. Once you break the step up into partitioning, each partition works independently.