SimpleAsyncTaskExecutor 在处理完成后尝试读取记录

Question

在我的 spring 批处理项目中，我需要从表中读取行列表，创建一个 4 块并进行处理，然后写入另一个表。我已经实现了 SimpleAsyncTaskExecutor 以允许并行处理块，但我发现在处理记录集中的所有记录之后，Spring Batch 正在尝试继续读取下一批结果并失败。超过跳过级别后，显然会中止工作。

我的查询是 - 为什么在处理完集合中的所有记录后批处理会继续寻找下一条记录？

我最后得到的错误是：

org.springframework.batch.core.step.item.FaultTolerantChunkProvider - 跳过失败的输入 org.springframework.jdbc.UncategorizedSQLException：尝试处理 下一行失败； SQL 的未分类 SQLException

下面是我的批处理 xml

<?xml version="1.0" encoding="UTF-8"?>
<beans:beans xmlns="http://www.springframework.org/schema/batch"
    xmlns:beans="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:util="http://www.springframework.org/schema/util"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/batch http://www.springframework.org/schema/batch/spring-batch-2.1.xsd
        http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd">

    <beans:import resource="../launch-context.xml" />

    <beans:bean id="wsStudentItemReader"
        class="org.springframework.batch.item.database.JdbcCursorItemReader"    
        scope="step">
        <beans:property name="dataSource" ref="rptDS" />
        <beans:property name="sql"
            value="SELECT * FROM STUDENTS WHERE BATCH_ID=?" />
        <beans:property name="preparedStatementSetter">
            <beans:bean class="com.test.BatchDtSetter"
                autowire="byName">
                <beans:property name="batchId" value="#{jobParameters[batchId]}" /> 
            </beans:bean>
        </beans:property>
        <beans:property name="rowMapper" ref="wsRowMapper" />
    </beans:bean>


 <beans:bean id="outputWriter"
        class="org.springframework.batch.item.support.ClassifierCompositeItemWriter">
        <beans:property name="classifier" ref="writerClassifier" >      
        </beans:property>       
 </beans:bean>  

<beans:bean id="writerClassifier"
    class="com.test.WriterClassifier">
    <beans:property name="codeFailWriter" ref="failJdbcBatchItemWriter" />
    <beans:property name="codePassWriter" ref="passJdbcBatchItemWriter"></beans:property>
</beans:bean>

    <beans:bean id="failJdbcBatchItemWriter"
        class="org.springframework.batch.item.database.JdbcBatchItemWriter">
        <beans:property name="dataSource" ref="rptDS" />
        <beans:property name="sql"
            value="DELETE FROM STUDENTS WHERE BATCH_ID=?" />
        <beans:property name="itemPreparedStatementSetter" ref="FailStatusSetter" />
    </beans:bean>

<beans:bean id="FailStatusSetter" class="com.test.FailStatusSetter" />

    <beans:bean id="passJdbcBatchItemWriter"
        class="com.test.PassBatchItemWriter">
    </beans:bean>

    <beans:bean id="WSListnr"
        class="com.test.WSBatchListnr">
        <beans:property name="dataSource" ref="rptDS" />
    </beans:bean>


    <beans:bean id="wsRowMapper" class="com.test.WSReqMapper" />
    <beans:bean id="wsReqPrcsr" 
         class="com.test.WSReqProc">
         <beans:property name="dataSource" ref="rptDS" />
    </beans:bean>
    <beans:bean id="wsReqPrepStmtSetter" class="com.test.wsStudentSetter" />

    <step id="initiateStep">
        <tasklet ref="initiateStepTask" />
    </step>
    <step id="wsStudentGenStep">
        <tasklet task-executor="taskExecutor">
            <chunk reader="wsStudentItemReader" processor="wsReqPrcsr"
                writer="outputWriter" commit-interval="4" skip-limit="20">
                <skippable-exception-classes>
                    <include class="java.lang.Exception" />
                </skippable-exception-classes>
            </chunk>
            <listeners> 
                <listener ref="WSListnr" />
            </listeners>            
        </tasklet>
    </step>
    <job id="wsStudent">
        <step id="wsStudentFileGenIntialStep" parent="initiateStep"
            next="wsStudentFileGenStep" />
        <step id="wsStudentFileGenStep" parent="wsStudentGenStep" />
    </job>


    <beans:bean id="initiateStepTask" class="com.test.Initializer"
        scope="step">
    </beans:bean>

    <beans:bean id="taskExecutor"
       class="org.springframework.core.task.SimpleAsyncTaskExecutor">
       <beans:property name="concurrencyLimit" value="2"/>
   </beans:bean>

</beans:beans>

Answer 1

使用 JdbcPagingItemReader 解决了该问题。此读取器将同步读取，并且还要求数据按特定列排序。