java - Grid Size in Spring batch

Question

I have batch job which reads data from bulk files, process it and insert in DB.

I'm using spring's partitioning features using the default partition handler.

    <bean class="org.spr...TaskExecutorPartitionHandler">
          <property name="taskExecutor" ref="taskExecutor"/>
          <property name="step" ref="readFromFile" />
          <property name="gridSize" value="10" />
    </bean>

What is the significance of the gridSize here ? I have configured in such a way that it is equal to the concurrency in taskExecutor.

Answer 1

gridSize specifies the number of data blocks to create to be processed by (usually) the same number of workers. Think about it as a number of mapped data blocks in a map/reduce.

Using a StepExecutionSplitter, given the data, PartitionHandler "partitions" / splits the data to a gridSize parts, and sends each part to an independent worker => thread in your case.

For example, you have 10 rows in DB that need to be processed. If you set the gridSize to be 5, and you are using a straightforward partition logic, you'd end up with 10 / 5 = 2 rows per thread => 5 threads working concurrently on 2 rows each.