Spring批处理：作业随机选择行数小于提交间隔的块

Question

我正面临着Spring批处理的问题。我们在作业中使用了一个任务执行器(simpleAsyncTaskExecutor)，它处理两个并行步骤的流程。

谢谢你。

下面是我的工作的配置（不包括我们的自定义编写器）：

    <batch:job id="job">

             <batch:split id="split" task-executor="taskExecutor">  
                <batch:flow> 
                    <batch:step id="step1"> 
                        <batch:tasklet task-executor="taskExecutor" throttle-limit="4" >
                              <batch:chunk reader="reader1" writer="writer1" commit-interval="24000" />         
                        </batch:tasklet>
                    </batch:step>
                </batch:flow>
                <batch:flow> 

                    <batch:step id="step2">
                        <batch:tasklet task-executor="taskExecutor" throttle-limit="4" >
                              <batch:chunk reader="reader2" writer="writer2" commit-interval="24000" />         
                        </batch:tasklet>
                    </batch:step>
                </batch:flow>       
             </batch:split>
        </batch:job>

    <bean id="reader1" class="org.springframework.batch.item.database.JdbcPagingItemReader" scope="step">       
         <property name="dataSource" ref="postgresql_1" />                           

         <property name="queryProvider">            
             <bean class="org.springframework.batch.item.database.support.PostgresPagingQueryProvider">
                    <property name="selectClause" value="
                        SELECT name
                    " />
                    <property name="fromClause" value="
                        FROM database.people
                    " />
                    <property name="whereClause" value="
                        WHERE age > 30
                    " />
                    <property name="sortKeys">
                        <map>
                            <entry key="people_id" value="ASCENDING"/>
                        </map>
                    </property>             
            </bean>         
        </property>         
        <property name="saveState" value="false" />         
        <property name="rowMapper">             
             <bean class="fr.myapp.PeopleRowMapper" />      
        </property>     
    </bean>

        <bean id="reader2" class="org.springframework.batch.item.database.JdbcPagingItemReader" scope="step">       
       <property name="dataSource" ref="postgresql_1" />        
       <property name="queryProvider">          
               <bean class="org.springframework.batch.item.database.support.PostgresPagingQueryProvider">
                    <property name="selectClause" value="
                         SELECT product_name
                    " />
                    <property name="fromClause" value="
                        FROM database.products
                    " />
                    <property name="whereClause" value="
                        WHERE product_order_date <= '01/11/2017'
                    " />
                    <property name="sortKeys">
                        <map>
                            <entry key="product_id" value="ASCENDING"/>
                        </map>
                    </property>             
               </bean>      
           </property>      
       <property name="saveState" value="false" />      
       <property name="rowMapper">
                <bean class="fr.myapp.ProductsRowMapper" />
       </property>  
    </bean>
    <bean id="taskExecutor" class="org.springframework.core.task.SimpleAsyncTaskExecutor">
          <property name="concurrencyLimit" value="8" />
    </bean>

Answer 1

在要写入的挂起记录数达到commit-interval（或块大小）之前，不应调用编写器的write（）方法。在此之前调用它的唯一时间是读取器中的read（）返回null，这表明没有更多的结果了。

当你看到较小的块是在工作的中间吗？行映射器中是否有任何逻辑或您省略的任何内容来滚动读取结果？