我正在编写一个使用 Spring Batch 处理 MySQL 数据库表中的 7,637,064 行的程序。我在较小的表上取得了成功,但是当 JdbcCursorItemReader 尝试打开游标时,此表中的大量行导致 OutOfMemoryError 异常。
我可能可以通过向它扔一个更大的 Xmx 来解决这个问题,但在我看来,Spring Batch 应该有一种方法来处理这个问题,而且我可能只是缺少一个关键的配置。
Spring批处理配置:
<job id="reportJob" xmlns="http://www.springframework.org/schema/batch">
<step id="largeTableTransfer">
<tasklet>
<chunk reader="largeTableReader" processor="largeTableTransformer" writer="largeTableWriter"
commit-interval="10" />
</tasklet>
</step>
</job>
<bean id="largeTableReader" class="org.springframework.batch.item.database.JdbcCursorItemReader">
<property name="dataSource" ref="inputDataSource" />
<property name="sql" value="select * from largeTable" />
<property name="rowMapper">
<bean class="myproject.reader.largeTableRowMapper" />
</property>
</bean>
<bean id="largeTableTransformer" class="myproject.transformer.LargeTableTransformer" />
<bean id="largeTableWriter" class="myproject.writer.JdbcLargeTableWriter">
<property name="dataSource" ref="outputDataSource" />
</bean>
在 JdbcCursorItemReader 上设置fetchSize似乎没有效果。唯一允许它运行完成的是将maxRows设置为一个较小的数字,但随后只会处理该数量的行。
相关的堆栈跟踪:
2012-11-21 11:25:29,931 DEBUG [org.springframework.batch.core.repository.dao.JdbcStepExecutionDao] - <Truncating long message before update of StepExecution, original message is: java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Arrays.java:2734)
at java.util.ArrayList.ensureCapacity(ArrayList.java:167)
at java.util.ArrayList.add(ArrayList.java:351)
at com.mysql.jdbc.MysqlIO.readSingleRowSet(MysqlIO.java:2821)
at com.mysql.jdbc.MysqlIO.getResultSet(MysqlIO.java:467)
at com.mysql.jdbc.MysqlIO.readResultsForQueryOrUpdate(MysqlIO.java:2510)
at com.mysql.jdbc.MysqlIO.readAllResults(MysqlIO.java:1746)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2135)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2542)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1734)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1885)
at org.apache.commons.dbcp.DelegatingPreparedStatement.executeQuery(DelegatingPreparedStatement.java:93)
at org.springframework.batch.item.database.JdbcCursorItemReader.openCursor(JdbcCursorItemReader.java:125)
at org.springframework.batch.item.database.AbstractCursorItemReader.doOpen(AbstractCursorItemReader.java:401)
at org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader.open(AbstractItemCountingItemStreamItemReader.java:134)
at org.springframework.batch.item.support.CompositeItemStream.open(CompositeItemStream.java:93)
at org.springframework.batch.core.step.tasklet.TaskletStep.open(TaskletStep.java:301)
at org.springframework.batch.core.step.AbstractStep.execute(AbstractStep.java:192)
at org.springframework.batch.core.job.SimpleStepHandler.handleStep(SimpleStepHandler.java:135)
at org.springframework.batch.core.job.flow.JobFlowExecutor.executeStep(JobFlowExecutor.java:61)
at org.springframework.batch.core.job.flow.support.state.StepState.handle(StepState.java:60)
at org.springframework.batch.core.job.flow.support.SimpleFlow.resume(SimpleFlow.java:144)
at org.springframework.batch.core.job.flow.support.SimpleFlow.start(SimpleFlow.java:124)
at org.springframework.batch.core.job.flow.FlowJob.doExecute(FlowJob.java:135)
at org.springframework.batch.core.job.AbstractJob.execute(AbstractJob.java:293)
at org.springframework.batch.core.launch.support.SimpleJobLauncher$1.run(SimpleJobLauncher.java:120)
at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:48)
at org.springframework.batch.core.launch.support.SimpleJobLauncher.run(SimpleJobLauncher.java:114)
at ifpress.ams2amx.ExampleJobConfigurationTests.testLaunchJob(ExampleJobConfigurationTests.java:32)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)