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你用剑🗡、我用刀🔪,好的代码都很烧😏,望你不吝出招💨!
一、前言介绍
在日常开发中经常会用到定时任务,用来;库表扫描发送MQ、T+n账单结算、缓存数据更新、秒杀活动状态变更,等等。因为有了Spring的Schedule极大的方便了我们对这类场景的使用。那么,除了应用你还了解它多少呢;
- 默认初始化多少个任务线程
- JobStore有几种实现,你平时用的都是哪个
- 一个定时任务的执行流程简述下
蒙圈了吧,是不感觉平时只是使用了,根本没关注过这些。有种冲动赶紧搜索答案吧!但只是知道答案是没有多少意义的,扛不住问不说,也不了解原理。所以,如果你想真的提升自己技能,还是要从根本搞定。
二、案例工程
为了更好的做源码分析,我们将平时用的定时任务服务单独抽离出来。工程下载,关注公众号:bugstack虫洞栈,回复:源码分析
itstack-demo-code-schedule
└── src
├── main
│ ├── java
│ │ └── org.itstack.demo
│ │ ├── DemoTask.java
│ │ └── JobImpl.java
│ └── resources
│ ├── props
│ │ └── config.properties
│ ├── spring
│ │ └── spring-config-schedule-task.xml
│ ├── logback.xml
│ └── spring-config.xml
└── test
└── java
└── org.itstack.demo.test
├── ApiTest.java
├── MyQuartz.java
└── MyTask.java
三、环境配置
- JDK 1.8
- IDEA 2019.3.1
- Spring 4.3.24.RELEASE
- quartz 2.3.2 {不同版本略有代码差异}
四、源码分析
<dependency>
<groupId>org.quartz-scheduler</groupId>
<artifactId>quartz</artifactId>
<version>2.3.2</version>
</dependency>
依赖于Spring版本升级quartz选择2.3.2,同时如果你如本文案例中所示使用xml配置任务。那么会有如下更改;
Spring 3.x/org.springframework.scheduling.quart.CronTriggerBean
<bean id="taskTrigger" class="org.springframework.scheduling.quartz.CronTriggerBean">
<property name="jobDetail" ref="taskHandler"/>
<property name="cronExpression" value="0/5 * * * * ?"/>
</bean>
Spring 4.x/org.springframework.scheduling.quartz.CronTriggerFactoryBean
<bean id="taskTrigger" class="org.springframework.scheduling.quartz.CronTriggerFactoryBean">
<property name="jobDetail" ref="taskHandler"/>
<property name="cronExpression" value="0/5 * * * * ?"/>
</bean>
在正式分析前,可以看下quartz的默认配置,很多初始化动作都要从这里取得参数,同样你可以配置自己的配置文件。例如,当你的任务很多时,默认初始化的10个线程组不满足你的业务需求,就可以按需调整。
quart.properties
# Default Properties file for use by StdSchedulerFactory
# to create a Quartz Scheduler Instance, if a different
# properties file is not explicitly specified.
#
org.quartz.scheduler.instanceName: DefaultQuartzScheduler
org.quartz.scheduler.rmi.export: false
org.quartz.scheduler.rmi.proxy: false
org.quartz.scheduler.wrapJobExecutionInUserTransaction: false
org.quartz.threadPool.class: org.quartz.simpl.SimpleThreadPool
org.quartz.threadPool.threadCount: 10
org.quartz.threadPool.threadPriority: 5
org.quartz.threadPool.threadsInheritContextClassLoaderOfInitializingThread: true
org.quartz.jobStore.misfireThreshold: 60000
org.quartz.jobStore.class: org.quartz.simpl.RAMJobStore
1. 从一个简单案例开始
平时我们使用Schedule基本都是注解或者xml配置文件,但是为了可以更简单的分析代码,我们从一个简单的Demo入手,放到main函数中。
DemoTask.java & 定义一个等待被执行的任务
public class DemoTask {
private Logger logger = LoggerFactory.getLogger(DemoTask.class);
public void execute() throws Exception{
logger.info("定时处理用户信息任务:0/5 * * * * ?");
}
}
MyTask.java & 测试类,将配置在xml中的代码抽离出来
public class MyTask {
public static void main(String[] args) throws Exception {
DemoTask demoTask = new DemoTask();
// 定义了;执行的内容
MethodInvokingJobDetailFactoryBean methodInvokingJobDetailFactoryBean = new MethodInvokingJobDetailFactoryBean();
methodInvokingJobDetailFactoryBean.setTargetObject(demoTask);
methodInvokingJobDetailFactoryBean.setTargetMethod("execute");
methodInvokingJobDetailFactoryBean.setConcurrent(true);
methodInvokingJobDetailFactoryBean.setName("demoTask");
methodInvokingJobDetailFactoryBean.afterPropertiesSet();
// 定义了;执行的计划
CronTriggerFactoryBean cronTriggerFactoryBean = new CronTriggerFactoryBean();
cronTriggerFactoryBean.setJobDetail(methodInvokingJobDetailFactoryBean.getObject());
cronTriggerFactoryBean.setCronExpression("0/5 * * * * ?");
cronTriggerFactoryBean.setName("demoTask");
cronTriggerFactoryBean.afterPropertiesSet();
// 实现了;执行的功能
SchedulerFactoryBean schedulerFactoryBean = new SchedulerFactoryBean();
schedulerFactoryBean.setTriggers(cronTriggerFactoryBean.getObject());
schedulerFactoryBean.setAutoStartup(true);
schedulerFactoryBean.afterPropertiesSet();
schedulerFactoryBean.start();
// 暂停住
System.in.read();
}
}
如果一切顺利,那么会有如下结果:
2020-01-04 10:47:16.369 [main] INFO org.quartz.impl.StdSchedulerFactory[1220] - Using default implementation for ThreadExecutor
2020-01-04 10:47:16.421 [main] INFO org.quartz.core.SchedulerSignalerImpl[61] - Initialized Scheduler Signaller of type: class org.quartz.core.SchedulerSignalerImpl
2020-01-04 10:47:16.422 [main] INFO org.quartz.core.QuartzScheduler[229] - Quartz Scheduler v.2.3.2 created.
2020-01-04 10:47:16.423 [main] INFO org.quartz.simpl.RAMJobStore[155] - RAMJobStore initialized.
2020-01-04 10:47:16.424 [main] INFO org.quartz.core.QuartzScheduler[294] - Scheduler meta-data: Quartz Scheduler (v2.3.2) 'QuartzScheduler' with instanceId 'NON_CLUSTERED'
Scheduler class: 'org.quartz.core.QuartzScheduler' - running locally.
NOT STARTED.
Currently in standby mode.
Number of jobs executed: 0
Using thread pool 'org.quartz.simpl.SimpleThreadPool' - with 10 threads.
Using job-store 'org.quartz.simpl.RAMJobStore' - which does not support persistence. and is not clustered.
2020-01-04 10:47:16.424 [main] INFO org.quartz.impl.StdSchedulerFactory[1374] - Quartz scheduler 'QuartzScheduler' initialized from an externally provided properties instance.
2020-01-04 10:47:16.424 [main] INFO org.quartz.impl.StdSchedulerFactory[1378] - Quartz scheduler version: 2.3.2
2020-01-04 10:47:16.426 [main] INFO org.quartz.core.QuartzScheduler[2293] - JobFactory set to: org.springframework.scheduling.quartz.AdaptableJobFactory@3e9b1010
2020-01-04 10:47:16.651 [main] INFO org.quartz.core.QuartzScheduler[547] - Scheduler QuartzScheduler_$_NON_CLUSTERED started.
一月 04, 2020 10:47:16 上午 org.springframework.scheduling.quartz.SchedulerFactoryBean startScheduler
信息: Starting Quartz Scheduler now
2020-01-04 10:47:20.321 [QuartzScheduler_Worker-1] INFO org.itstack.demo.DemoTask[11] - 定时处理用户信息任务:0/5 * * * * ?
2020-01-04 10:47:25.001 [QuartzScheduler_Worker-2] INFO org.itstack.demo.DemoTask[11] - 定时处理用户信息任务:0/5 * * * * ?
2020-01-04 10:47:30.000 [QuartzScheduler_Worker-3] INFO org.itstack.demo.DemoTask[11] - 定时处理用户信息任务:0/5 * * * * ?
2020-01-04 10:47:35.001 [QuartzScheduler_Worker-4] INFO org.itstack.demo.DemoTask[11] - 定时处理用户信息任务:0/5 * * * * ?
2020-01-04 10:47:40.000 [QuartzScheduler_Worker-5] INFO org.itstack.demo.DemoTask[11] - 定时处理用户信息任务:0/5 * * * * ?
Process finished with exit code -1
2. 定义执行内容(MethodInvokingJobDetailFactoryBean)
// 定义了;执行的内容
MethodInvokingJobDetailFactoryBean methodInvokingJobDetailFactoryBean = new MethodInvokingJobDetailFactoryBean();
methodInvokingJobDetailFactoryBean.setTargetObject(demoTask);
methodInvokingJobDetailFactoryBean.setTargetMethod("execute");
methodInvokingJobDetailFactoryBean.setConcurrent(true);
methodInvokingJobDetailFactoryBean.setName("demoTask");
methodInvokingJobDetailFactoryBean.afterPropertiesSet();
这块内容主要将我们的任务体(即待执行任务DemoTask)交给MethodInvokingJobDetailFactoryBean管理,首先设置必要信息;
- targetObject:目标对象bean,也就是demoTask
- targetMethod:目标方法name,也就是execute
- concurrent:是否并行执行,非并行执行任务,如果上一个任务没有执行完,下一刻不会执行
- name:xml配置非必传,源码中可以获取beanName
最后我们通过手动调用 afterPropertiesSet() 来模拟初始化。如果我们的类是交给 Spring 管理的,那么在实现了 InitializingBean 接口的类,在类配置信息加载后会自动执行 afterPropertiesSet() 。一般实现了 InitializingBean 接口的类,同时也会去实现 FactoryBean 接口,因为这个接口实现后就可以通过 T getObject() 获取自己自定义初始化的类。这也常常用在一些框架开发中。
MethodInvokingJobDetailFactoryBean.afterPropertiesSet()
public void afterPropertiesSet() throws ClassNotFoundException, NoSuchMethodException {
prepare();
// Use specific name if given, else fall back to bean name.
String name = (this.name != null ? this.name : this.beanName);
// Consider the concurrent flag to choose between stateful and stateless job.
Class<?> jobClass = (this.concurrent ? MethodInvokingJob.class : StatefulMethodInvokingJob.class);
// Build JobDetail instance.
JobDetailImpl jdi = new JobDetailImpl();
jdi.setName(name);
jdi.setGroup(this.group);
jdi.setJobClass((Class) jobClass);
jdi.setDurability(true);
jdi.getJobDataMap().put("methodInvoker", this);
this.jobDetail = jdi;
postProcessJobDetail(this.jobDetail);
}
-
源码168行: 根据是否并行执行选择任务类,这两个类都是MethodInvokingJobDetailFactoryBean的内部类,非并行执行的StatefulMethodInvokingJob只是继承MethodInvokingJob添加了标记注解。
-
源码171行: 创建JobDetailImpl,添加任务明细信息,注意这类的jdi.setJobClass((Class) jobClass)实际就是MethodInvokingJob。MethodInvokingJob也是我们最终要反射调用执行的内容。
-
源码177行: 初始化任务后赋值给this.jobDetail = jdi,也就是最终的类对象
MethodInvokingJobDetailFactoryBean.getObject()
@Override public JobDetail getObject() { return this.jobDetail; }
-
源码:220行: 获取对象时返回 this.jobDetail,这也就解释了为什么 MethodInvokingJobDetailFactoryBean 初始化后直接赋值给了一个 JobDetail ;
3. 定义执行计划(CronTriggerFactoryBeann)
// 定义了;执行的计划
CronTriggerFactoryBean cronTriggerFactoryBean = new CronTriggerFactoryBean();
cronTriggerFactoryBean.setJobDetail(methodInvokingJobDetailFactoryBean.getObject());
cronTriggerFactoryBean.setCronExpression("0/5 * * * * ?");
cronTriggerFactoryBean.setName("demoTask");
cronTriggerFactoryBean.afterPropertiesSet();
这一块主要定义任务的执行计划,并将任务执行内容交给 CronTriggerFactoryBean 管理,同时设置必要信息;
- jobDetail:设置任务体,xml 中可以直接将对象赋值,硬编码中设置执行的 JobDetail 对象信息。也就是我们上面设置的 JobDetailImpl ,通过 getObject() 获取出来。
- cronExpression:计划表达式;秒、分、时、日、月、周、年
CronTriggerFactoryBean.afterPropertiesSet()
@Override
public void afterPropertiesSet() throws ParseException {
// ... 校验属性信息
CronTriggerImpl cti = new CronTriggerImpl();
cti.setName(this.name);
cti.setGroup(this.group);
if (this.jobDetail != null) {
cti.setJobKey(this.jobDetail.getKey());
}
cti.setJobDataMap(this.jobDataMap);
cti.setStartTime(this.startTime);
cti.setCronExpression(this.cronExpression);
cti.setTimeZone(this.timeZone);
cti.setCalendarName(this.calendarName);
cti.setPriority(this.priority);
cti.setMisfireInstruction(this.misfireInstruction);
cti.setDescription(this.description);
this.cronTrigger = cti;
}
-
源码237行: 创建触发器 CronTriggerImpl 并设置相关属性信息
-
源码245行: 生成执行计划类 cti.setCronExpression(this.cronExpression);
public void setCronExpression(String cronExpression) throws ParseException { TimeZone origTz = getTimeZone(); this.cronEx = new CronExpression(cronExpression); this.cronEx.setTimeZone(origTz); }
CronExpression.java & 解析Cron表达式
protected void buildExpression(String expression) throws ParseException { expressionParsed = true; try { // ... 初始化 TreeSet xxx = new TreeSet<Integer>(); int exprOn = SECOND; StringTokenizer exprsTok = new StringTokenizer(expression, " \t", false); while (exprsTok.hasMoreTokens() && exprOn <= YEAR) { String expr = exprsTok.nextToken().trim(); // ... 校验DAY_OF_MONTH和DAY_OF_WEEK字段的特殊字符 StringTokenizer vTok = new StringTokenizer(expr, ","); while (vTok.hasMoreTokens()) { String v = vTok.nextToken(); storeExpressionVals(0, v, exprOn); } exprOn++; } // ... 校验DAY_OF_MONTH和DAY_OF_WEEK字段的特殊字符 } catch (ParseException pe) { throw pe; } catch (Exception e) { throw new ParseException("Illegal cron expression format (" + e.toString() + ")", 0); } }
- Cron表达式有7个字段,CronExpression 把7个字段解析为7个 TreeSet 对象。
- 填充TreeSet对象值的时候,表达式都会转换为起始值、结束值和增量的计算模式,然后计算出匹配的值放进TreeSet对象
CronTriggerFactoryBean.getObject()
@Override
public CronTrigger getObject() {
return this.cronTrigger;
}
- 源码257行: 获取对象时返回 this.cronTrigger ,也就是 CronTriggerImpl 对象
4. 调度执行计划(SchedulerFactoryBean)
// 调度了;执行的计划(scheduler)
SchedulerFactoryBean schedulerFactoryBean = new SchedulerFactoryBean();
schedulerFactoryBean.setTriggers(cronTriggerFactoryBean.getObject());
schedulerFactoryBean.setAutoStartup(true);
schedulerFactoryBean.afterPropertiesSet();
schedulerFactoryBean.start();
这一部分如名字一样调度工厂,相当于一个指挥官,可以从全局做调度,比如监听哪些trigger已经ready、分配线程等等,同样也需要设置必要的属性信息;
- triggers:按需可以设置多个触发器,本文设置了一个 cronTriggerFactoryBean.getObject() 也就是 CronTriggerImpl 对象
- autoStartup:默认是否自动启动任务,默认值为true
这个过程较长包括:调度工厂、线程池、注册任务等等,整体核心加载流程如下;
- 整个加载过程较长,抽取部分核心代码块进行分析,其中包括的类;
- StdScheduler
- StdSchedulerFactory
- SimpleThreadPool
- QuartzScheduler
- QuartzSchedulerThread
- RAMJobStore
- CronTriggerImpl
- CronExpression
SchedulerFactoryBean.afterPropertiesSet()
public void afterPropertiesSet() throws Exception {
if (this.dataSource == null && this.nonTransactionalDataSource != null) {
this.dataSource = this.nonTransactionalDataSource;
}
if (this.applicationContext != null && this.resourceLoader == null) {
this.resourceLoader = this.applicationContext;
}
// Initialize the Scheduler instance...
this.scheduler = prepareScheduler(prepareSchedulerFactory());
try {
registerListeners();
registerJobsAndTriggers();
}
catch (Exception ex) {
try {
this.scheduler.shutdown(true);
}
catch (Exception ex2) {
logger.debug("Scheduler shutdown exception after registration failure", ex2);
}
throw ex;
}
}
-
源码474行: 为调度器做准备工作 prepareScheduler(prepareSchedulerFactory()) ,依次执行如下;
- SchedulerFactoryBean.prepareScheduler(SchedulerFactory schedulerFactory)
- SchedulerFactoryBean.createScheduler(schedulerFactory, this.schedulerName);
- SchedulerFactoryBean.createScheduler(SchedulerFactory schedulerFactory, String schedulerName)
- Scheduler newScheduler = schedulerFactory.getScheduler();
- StdSchedulerFactory.getScheduler();
- sched = instantiate(); 包括一系列核心操作;
1)初始化threadPool(线程池):开发者可以通过org.quartz.threadPool.class配置指定使用哪个线程池类,比如SimpleThreadPool。 2)初始化jobStore(任务存储方式):开发者可以通过org.quartz.jobStore.class配置指定使用哪个任务存储类,比如RAMJobStore。 3)初始化dataSource(数据源):开发者可以通过org.quartz.dataSource配置指定数据源详情,比如哪个数据库、账号、密码等。 4)初始化其他配置:包括SchedulerPlugins、JobListeners、TriggerListeners等; 5)初始化threadExecutor(线程执行器):默认为DefaultThreadExecutor; 6)创建工作线程:根据配置创建N个工作thread,执行start()启动thread,并将N个thread顺序add进threadPool实例的空闲线程列表availWorkers中; 7)创建调度器线程:创建QuartzSchedulerThread实例,并通过threadExecutor.execute(实例)启动调度器线程; 8)创建调度器:创建StdScheduler实例,将上面所有配置和引用组合进实例中,并将实例存入调度器池中
-
源码477行: 调用父类 SchedulerAccessor.registerJobsAndTriggers() 注册任务和触发器
for (Trigger trigger : this.triggers) { addTriggerToScheduler(trigger); }
SchedulerAccessor.addTriggerToScheduler() & SchedulerAccessor 是SchedulerFactoryBean的父类
private boolean addTriggerToScheduler(Trigger trigger) throws SchedulerException {
boolean triggerExists = (getScheduler().getTrigger(trigger.getKey()) != null);
if (triggerExists && !this.overwriteExistingJobs) {
return false;
}
// Check if the Trigger is aware of an associated JobDetail.
JobDetail jobDetail = (JobDetail) trigger.getJobDataMap().remove("jobDetail");
if (triggerExists) {
if (jobDetail != null && !this.jobDetails.contains(jobDetail) && addJobToScheduler(jobDetail)) {
this.jobDetails.add(jobDetail);
}
try {
getScheduler().rescheduleJob(trigger.getKey(), trigger);
}
catch (ObjectAlreadyExistsException ex) {
if (logger.isDebugEnabled()) {
logger.debug("Unexpectedly encountered existing trigger on rescheduling, assumably due to " +
"cluster race condition: " + ex.getMessage() + " - can safely be ignored");
}
}
}
else {
try {
if (jobDetail != null && !this.jobDetails.contains(jobDetail) &&
(this.overwriteExistingJobs || getScheduler().getJobDetail(jobDetail.getKey()) == null)) {
getScheduler().scheduleJob(jobDetail, trigger);
this.jobDetails.add(jobDetail);
}
else {
getScheduler().scheduleJob(trigger);
}
}
catch (ObjectAlreadyExistsException ex) {
if (logger.isDebugEnabled()) {
logger.debug("Unexpectedly encountered existing trigger on job scheduling, assumably due to " +
"cluster race condition: " + ex.getMessage() + " - can safely be ignored");
}
if (this.overwriteExistingJobs) {
getScheduler().rescheduleJob(trigger.getKey(), trigger);
}
}
}
return true;
}
-
源码299行: addJobToScheduler(jobDetail) 一直会调用到 RAMJobStore 进行存放任务信息到 HashMap<JobKey, JobWrapper>(100)
public void storeJob(JobDetail newJob, boolean replaceExisting) throws ObjectAlreadyExistsException { JobWrapper jw = new JobWrapper((JobDetail)newJob.clone()); boolean repl = false; synchronized (lock) { if (jobsByKey.get(jw.key) != null) { if (!replaceExisting) { throw new ObjectAlreadyExistsException(newJob); } repl = true; } if (!repl) { // get job group HashMap<JobKey, JobWrapper> grpMap = jobsByGroup.get(newJob.getKey().getGroup()); if (grpMap == null) { grpMap = new HashMap<JobKey, JobWrapper>(100); jobsByGroup.put(newJob.getKey().getGroup(), grpMap); } // add to jobs by group grpMap.put(newJob.getKey(), jw); // add to jobs by FQN map jobsByKey.put(jw.key, jw); } else { // update job detail JobWrapper orig = jobsByKey.get(jw.key); orig.jobDetail = jw.jobDetail; // already cloned } } }
-
初始化线程组;
- prepareScheduler
- createScheduler
- schedulerFactory
- StdSchedulerFactory.getScheduler()
- getScheduler()->instantiate()
- 源码1323行: tp.initialize();
SimpleThreadPool.initialize() & 这里的count是默认配置中的数量,可以更改
// create the worker threads and start them Iterator<WorkerThread> workerThreads = createWorkerThreads(count).iterator(); while(workerThreads.hasNext()) { WorkerThread wt = workerThreads.next(); wt.start(); availWorkers.add(wt); }
5. 启动定时任务
案例中使用硬编码方式调用 schedulerFactoryBean.start() 启动线程服务。线程的协作通过Object sigLock来实现,关于sigLock.wait()方法都在QuartzSchedulerThread的run方法里面,所以sigLock唤醒的是只有线程QuartzSchedulerThread。核心流程如下;
这个启动过程中,核心的代码类,如下;
- StdScheduler
- QuartzScheduler
- QuartzSchedulerThread
- ThreadPool
- RAMJobStore
- CronTriggerImpl
- JobRunShellFactory
QuartzScheduler.start() & 启动
public void start() throws SchedulerException {
if (shuttingDown|| closed) {
throw new SchedulerException(
"The Scheduler cannot be restarted after shutdown() has been called.");
}
// QTZ-212 : calling new schedulerStarting() method on the listeners
// right after entering start()
notifySchedulerListenersStarting();
if (initialStart == null) {
initialStart = new Date();
this.resources.getJobStore().schedulerStarted();
startPlugins();
} else {
resources.getJobStore().schedulerResumed();
}
// 唤醒线程
schedThread.togglePause(false);
getLog().info(
"Scheduler " + resources.getUniqueIdentifier() + " started.");
notifySchedulerListenersStarted();
}
QuartzSchedulerThread.run() & 执行过程
@Override
public void run() {
int acquiresFailed = 0;
// 只有调用了halt()方法,才会退出这个死循环
while (!halted.get()) {
try {
// 一、如果是暂停状态,则循环超时等待1000毫秒
// wait a bit, if reading from job store is consistently failing (e.g. DB is down or restarting)..
// 阻塞直到有空闲的线程可用并返回可用的数量
int availThreadCount = qsRsrcs.getThreadPool().blockForAvailableThreads();
if(availThreadCount > 0) {
List<OperableTrigger> triggers;
long now = System.currentTimeMillis();
clearSignaledSchedulingChange();
try {
// 二、获取acquire状态的Trigger列表,也就是即将执行的任务
triggers = qsRsrcs.getJobStore().acquireNextTriggers(
now + idleWaitTime, Math.min(availThreadCount, qsRsrcs.getMaxBat
acquiresFailed = 0;
if (log.isDebugEnabled())
log.debug("batch acquisition of " + (triggers == null ? 0 : triggers
} catch(){//...}
if (triggers != null && !triggers.isEmpty()) {
// 三:获取List第一个Trigger的下次触发时刻
long triggerTime = triggers.get(0).getNextFireTime().getTime();
// 四:获取任务触发集合
List<TriggerFiredResult> res = qsRsrcs.getJobStore().triggersFired(triggers);
// 五:设置Triggers为'executing'状态
qsRsrcs.getJobStore().releaseAcquiredTrigger(triggers.get(i));
// 六:创建JobRunShell
qsRsrcs.getJobRunShellFactory().createJobRunShell(bndle);
// 七:执行Job
qsRsrcs.getThreadPool().runInThread(shell)
continue; // while (!halted)
}
} else { // if(availThreadCount > 0)
// should never happen, if threadPool.blockForAvailableThreads() follows con
continue; // while (!halted)
}
} catch(RuntimeException re) {
getLog().error("Runtime error occurred in main trigger firing loop.", re);
}
}
qs = null;
qsRsrcs = null;
}
-
源码391行: 创建JobRunShell,JobRunShell实例在initialize()方法就会把包含业务逻辑类的JobDetailImpl设置为它的成员属性,为后面执行业务逻辑代码做准备。执行业务逻辑代码在runInThread(shell)方法里面。
QuartzSchedulerThread.run() & 部分代码
JobRunShell shell = null; try { shell = qsRsrcs.getJobRunShellFactory().createJobRunShell(bndle); shell.initialize(qs); } catch (SchedulerException se) { qsRsrcs.getJobStore().triggeredJobComplete(triggers.get(i), bndle.getJobDetail(), CompletedExecutionInstruction.SET_ALL_JOB_TRIGGERS_ERROR); continue; }
-
源码398行: qsRsrcs.getThreadPool().runInThread(shell)
SimpleThreadPool.runInThread
// 保存所有WorkerThread的集合 private List<WorkerThread> workers; // 空闲的WorkerThread集合 private LinkedList<WorkerThread> availWorkers = new LinkedList<WorkerThread>(); // 任务的WorkerThread集合 private LinkedList<WorkerThread> busyWorkers = new LinkedList<WorkerThread>(); /** * 维护workers、availWorkers和busyWorkers三个列表数据 * 有任务需要一个线程出来执行:availWorkers.removeFirst();busyWorkers.add() * 然后调用WorkThread.run(runnable)方法 */ public boolean runInThread(Runnable runnable) { if (runnable == null) { return false; } synchronized (nextRunnableLock) { handoffPending = true; // Wait until a worker thread is available while ((availWorkers.size() < 1) && !isShutdown) { try { nextRunnableLock.wait(500); } catch (InterruptedException ignore) { } } if (!isShutdown) { WorkerThread wt = (WorkerThread)availWorkers.removeFirst(); busyWorkers.add(wt); wt.run(runnable); } else { // If the thread pool is going down, execute the Runnable // within a new additional worker thread (no thread from the pool). WorkerThread wt = new WorkerThread(this, threadGroup, "WorkerThread-LastJob", prio, isMakeThreadsDaemons(), runnable); busyWorkers.add(wt); workers.add(wt); wt.start(); } nextRunnableLock.notifyAll(); handoffPending = false; } return true; }
-
源码428行: WorkerThread ,是一个内部类,主要是赋值并唤醒lock对象的等待线程队列
WorkerThread.run(Runnable newRunnable)
public void run(Runnable newRunnable) { synchronized(lock) { if(runnable != null) { throw new IllegalStateException("Already running a Runnable!"); } runnable = newRunnable; lock.notifyAll(); } }
-
源码561行: WorkerThread 的run方法,方法执行lock.notifyAll()后,对应的WorkerThread就会来到run()方法。到这!接近曙光了!终于来到了执行业务的execute()方法的倒数第二步,runnable对象是一个JobRunShell对象,下面在看JobRunShell.run()方法。
WorkerThread.run()
@Override public void run() { boolean ran = false; while (run.get()) { try { synchronized(lock) { while (runnable == null && run.get()) { lock.wait(500); } if (runnable != null) { ran = true; // 启动真正执行的内容,runnable就是JobRunShell runnable.run(); } } } cache(){//...} } //if (log.isDebugEnabled()) try { getLog().debug("WorkerThread is shut down."); } catch(Exception e) { // ignore to help with a tomcat glitch } }
JobRunShell.run() & 从上面WorkerThread.run(),调用到这里执行
public void run() {
qs.addInternalSchedulerListener(this);
try {
OperableTrigger trigger = (OperableTrigger) jec.getTrigger();
JobDetail jobDetail = jec.getJobDetail();
do {
// ...
long startTime = System.currentTimeMillis();
long endTime = startTime;
// execute the job
try {
log.debug("Calling execute on job " + jobDetail.getKey());
// 执行业务代码,也就是我们的task
job.execute(jec);
endTime = System.currentTimeMillis();
} catch (JobExecutionException jee) {
endTime = System.currentTimeMillis();
jobExEx = jee;
getLog().info("Job " + jobDetail.getKey() +
" threw a JobExecutionException: ", jobExEx);
} catch (Throwable e) {
endTime = System.currentTimeMillis();
getLog().error("Job " + jobDetail.getKey() +
" threw an unhandled Exception: ", e);
SchedulerException se = new SchedulerException(
"Job threw an unhandled exception.", e);
qs.notifySchedulerListenersError("Job ("
+ jec.getJobDetail().getKey()
+ " threw an exception.", se);
jobExEx = new JobExecutionException(se, false);
}
jec.setJobRunTime(endTime - startTime);
// 其他代码
} while (true);
} finally {
qs.removeInternalSchedulerListener(this);
}
}
QuartzJobBean.execte() & 继续往下走
public final void execute(JobExecutionContext context) throws JobExecutionException {
try {
BeanWrapper bw = PropertyAccessorFactory.forBeanPropertyAccess(this);
MutablePropertyValues pvs = new MutablePropertyValues();
pvs.addPropertyValues(context.getScheduler().getContext());
pvs.addPropertyValues(context.getMergedJobDataMap());
bw.setPropertyValues(pvs, true);
}
catch (SchedulerException ex) {
throw new JobExecutionException(ex);
}
executeInternal(context);
}
MethodInvokingJobDetailFactoryBean->MethodInvokingJob.executeInternal(JobExecutionContext context)
protected void executeInternal(JobExecutionContext context) throws JobExecutionException {
try {
// 反射执行业务代码
context.setResult(this.methodInvoker.invoke());
}
catch (InvocationTargetException ex) {
if (ex.getTargetException() instanceof JobExecutionException) {
// -> JobExecutionException, to be logged at info level by Quartz
throw (JobExecutionException) ex.getTargetException();
}
else {
// -> "unhandled exception", to be logged at error level by Quartz
throw new JobMethodInvocationFailedException(this.methodInvoker, ex.getTargetException());
}
}
catch (Exception ex) {
// -> "unhandled exception", to be logged at error level by Quartz
throw new JobMethodInvocationFailedException(this.methodInvoker, ex);
}
}
五、综上总结
- quartz,即石英的意思,隐喻如石英钟般对时间的准确把握。
- 源码分析是一个很快乐的过程,这个快乐是分析完才能获得的快乐。纵横交互的背后是面向对象的高度解耦,对线程精彩的使用,将任务执行做成计划单,简直是一个超级棒的作品。
- 对于quartz.properties,简单场景下,开发者不用自定义配置,使用quartz默认配置即可,但在要求较高的使用场景中还是要自定义配置,比如通过org.quartz.threadPool.threadCount设置足够的线程数可提高多job场景下的运行性能。
- quartz 对任务处理高度解耦,job与trigger解藕,将任务本身和任务执行策略解藕,这样可以方便实现N个任务和M个执行策略自由组合。
- scheduler单独分离出来,相当于一个指挥官,可以从全局做调度,比如监听哪些trigger已经ready、分配线程等等。
- 外部链接:
今天的文章源码分析 | Spring定时任务Quartz执行全过程源码解读分享到此就结束了,感谢您的阅读。
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