Spring Batch_Parallel Steps_使用并行的Step

spring 官方文档：http://docs.spring.io/spring-batch/trunk/reference/html/scalability.html#scalabilityParallelSteps

As long as the application logic that needs to be parallelized can be split into distinct responsibilities, and assigned to individual steps then it can be parallelized in a single process. Parallel Step execution is easy to configure and use, for example, to execute steps (step1,step2) in parallel with step3, you could configure a flow like this:

<job id="job1">
    <split id="split1" task-executor="taskExecutor" next="step4">
        <flow>
            <step id="step1" parent="s1" next="step2"/>
            <step id="step2" parent="s2"/>
        </flow>
        <flow>
            <step id="step3" parent="s3"/>
        </flow>
    </split>
    <step id="step4" parent="s4"/>
</job>

<beans:bean id="taskExecutor" class="org.spr...SimpleAsyncTaskExecutor"/>

The configurable "task-executor" attribute is used to specify which TaskExecutor implementation should be used to execute the individual flows. The default is SyncTaskExecutor, but an asynchronous TaskExecutor is required to run the steps in parallel. Note that the job will ensure that every flow in the split completes before aggregating the exit statuses and transitioning.

多个step之间的并行化，可以提高批处理的效率。什么情况下可以应用step之间的并行化，那就要根据具体的业务需求来定。

那我们假设有这样一种场景：有一类数据，分别存在于文件和数据库，数据的内容一样，只是形式不一样，那么我们可以定义并行的step来分别处理来自文件的数据和来自数据库的数据，然后，分别进行同样的processor，然后写入数据库。

下面我们就刚才讲的那种场景实现我们并行的step，如下：

spring-batch-split.xml

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:batch="http://www.springframework.org/schema/batch"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
		http://www.springframework.org/schema/batch http://www.springframework.org/schema/batch/spring-batch.xsd
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
	<!-- 包的扫描 -->
	<context:component-scan base-package="com.lyx.batch" />

	<bean id="exceptionHandler" class="com.lyx.batch.ExceptionListener" />

	<batch:step id="abstractStep" abstract="true">
		<batch:listeners>
			<batch:listener ref="exceptionHandler" />
		</batch:listeners>
	</batch:step>
	<bean id="abstractCursorReader" abstract="true"
		class="org.springframework.batch.item.database.JdbcCursorItemReader">
		<property name="dataSource" ref="dataSource" />
	</bean>

	<bean id="taskExecutor" class="org.springframework.core.task.SimpleAsyncTaskExecutor" />
	<!-- 并行的step -->
	<batch:job id="addPeopleDescJob">
		<batch:split id="split1" task-executor="taskExecutor">
			<batch:flow>
				<batch:step id="parallel_step_1">
					<batch:tasklet>
						<batch:chunk reader="peopleAddDescReader_db"
							processor="addDescProcessor" writer="addDescPeopleWriter"
							commit-interval="10" />
					</batch:tasklet>
				</batch:step>
			</batch:flow>
			<batch:flow>
				<batch:step id="parallel_step_2">
					<batch:tasklet>
						<batch:chunk reader="peopleAddDescReader_file"
							processor="addDescProcessor" writer="addDescPeopleWriter"
							commit-interval="10" />
					</batch:tasklet>
				</batch:step>
			</batch:flow>
		</batch:split>
	</batch:job>

	<!-- 从数据库读取数据的reader -->
	<bean id="peopleAddDescReader_db" parent="abstractCursorReader"
		scope="step">
		<property name="sql">
			<value><![CDATA[select first_name ,last_name from people where 
			first_name like ? or last_name like ?]]></value>
		</property>
		<property name="rowMapper" ref="peopleRowMapper" />
		<property name="preparedStatementSetter" ref="preparedStatementSetter" />
		<property name="fetchSize" value="20" />
	</bean>
	<bean id="peopleRowMapper" class="com.lyx.batch.PeopleRowMapper" />
	<bean id="preparedStatementSetter" class="com.lyx.batch.PeoplePreparedStatementSetter" />
	<bean id="addDescProcessor" class="com.lyx.batch.AddPeopleDescProcessor" />
	<bean id="addDescPeopleWriter" class="com.lyx.batch.AddDescPeopleWriter" />

	<!-- 从文件中读取数据的reader -->
	<bean id="lineTokenizer"
		class="org.springframework.batch.item.file.transform.DelimitedLineTokenizer">
		<property name="delimiter" value="," />
		<property name="names">
			<list>
				<value>firstName</value>
				<value>lastName</value>
			</list>
		</property>
	</bean>
	<bean id="fieldSetMapper"
		class="org.springframework.batch.item.file.mapping.BeanWrapperFieldSetMapper">
		<property name="prototypeBeanName" value="people" />
	</bean>
	<bean id="people" class="com.lyx.batch.People" scope="prototype" />
	<bean id="lineMapper"
		class="org.springframework.batch.item.file.mapping.DefaultLineMapper">
		<property name="lineTokenizer" ref="lineTokenizer" />
		<property name="fieldSetMapper" ref="fieldSetMapper" />
	</bean>
	<bean id="resource" class="org.springframework.core.io.ClassPathResource">
		<constructor-arg index="0" type="java.lang.String"
			value="sample-data.csv" />
	</bean>
	<bean id="peopleAddDescReader_file" class="org.springframework.batch.item.file.FlatFileItemReader">
		<property name="resource" ref="resource" />
		<property name="encoding" value="utf-8" />
		<property name="lineMapper" ref="lineMapper" />
	</bean>
	<!--从文件读取数据的reader end -->

	<!--tomcat jdbc pool数据源配置 -->
	<bean id="dataSource" class="org.apache.tomcat.jdbc.pool.DataSource"
		destroy-method="close">
		<property name="poolProperties">
			<bean class="org.apache.tomcat.jdbc.pool.PoolProperties">
				<property name="driverClassName" value="com.mysql.jdbc.Driver" />
				<property name="url" value="jdbc:mysql://localhost:3306/test" />
				<property name="username" value="root" />
				<property name="password" value="034039" />
			</bean>
		</property>
	</bean>

	<!-- spring batch 配置jobRepository -->
	<batch:job-repository id="jobRepository"
		data-source="dataSource" transaction-manager="transactionManager"
		isolation-level-for-create="REPEATABLE_READ" table-prefix="BATCH_"
		max-varchar-length="1000" />
	<!-- spring的事务管理器 -->
	<bean id="transactionManager"
		class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
		<property name="dataSource" ref="dataSource" />
	</bean>

	<!-- batch luncher -->
	<bean id="jobLauncher"
		class="org.springframework.batch.core.launch.support.SimpleJobLauncher">
		<property name="jobRepository" ref="jobRepository" />
	</bean>
</beans>

以上配置如果略显突兀，请在前面一系列spring batch的文章中找到出处

以上就是step 并行化的主要配置。。

AppMain7.java

package com.lyx.batch;

import org.springframework.batch.core.ExitStatus;
import org.springframework.batch.core.Job;
import org.springframework.batch.core.JobExecution;
import org.springframework.batch.core.JobParametersBuilder;
import org.springframework.batch.core.JobParametersInvalidException;
import org.springframework.batch.core.launch.JobLauncher;
import org.springframework.batch.core.repository.JobExecutionAlreadyRunningException;
import org.springframework.batch.core.repository.JobInstanceAlreadyCompleteException;
import org.springframework.batch.core.repository.JobRestartException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * 测试并行的job
 * 
 * @author Lenovo
 *
 */
public class AppMain7 {

	public static void main(String[] args)
			throws JobExecutionAlreadyRunningException, JobRestartException,
			JobInstanceAlreadyCompleteException, JobParametersInvalidException {

		long startTime = System.currentTimeMillis(); // 获取开始时间

		@SuppressWarnings("resource")
		ApplicationContext context = new ClassPathXmlApplicationContext(
				new String[] { "classpath:spring-batch-split.xml" });
		JobParametersBuilder jobParametersBuilder = new JobParametersBuilder();
		Job job = (Job) context.getBean("addPeopleDescJob");
		JobLauncher launcher = (JobLauncher) context.getBean("jobLauncher");
		JobExecution result = launcher.run(job,
				jobParametersBuilder.toJobParameters());
		ExitStatus es = result.getExitStatus();
		if (es.getExitCode().equals(ExitStatus.COMPLETED.getExitCode())) {
			System.out.println("任务正常完成");
		} else {
			System.out.println("任务失败，exitCode=" + es.getExitCode());
		}

		long endTime = System.currentTimeMillis(); // 获取结束时间
		System.out.println("程序运行时间： " + (endTime - startTime) + "ms");
	}

}

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