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源碼分析 | Spring定時(shí)任務(wù)Quartz執(zhí)行全過程源碼解讀

 小傅哥 2021-12-13

微信公眾號(hào):bugstack蟲洞棧

微信公眾號(hào):bugstack蟲洞棧 | 博客:https://

沉淀、分享、成長,專注于原創(chuàng)專題案例,以最易學(xué)習(xí)編程的方式分享知識(shí),讓自己和他人都能有所收獲。目前已完成的專題有;Netty4.x實(shí)戰(zhàn)專題案例、用Java實(shí)現(xiàn)JVM、基于JavaAgent的全鏈路監(jiān)控、手寫RPC框架、架構(gòu)設(shè)計(jì)專題案例[Ing]等。

你用劍🗡、我用刀🔪,好的代碼都很燒😏,望你不吝出招💨!

一、前言介紹

在日常開發(fā)中經(jīng)常會(huì)用到定時(shí)任務(wù),用來;庫表掃描發(fā)送MQ、T+n賬單結(jié)算、緩存數(shù)據(jù)更新、秒殺活動(dòng)狀態(tài)變更,等等。因?yàn)橛辛薙pring的Schedule極大的方便了我們對(duì)這類場景的使用。那么,除了應(yīng)用你還了解它多少呢;

  1. 默認(rèn)初始化多少個(gè)任務(wù)線程
  2. JobStore有幾種實(shí)現(xiàn),你平時(shí)用的都是哪個(gè)
  3. 一個(gè)定時(shí)任務(wù)的執(zhí)行流程簡述下

蒙圈了吧,是不感覺平時(shí)只是使用了,根本沒關(guān)注過這些。有種沖動(dòng)趕緊搜索答案吧!但只是知道答案是沒有多少意義的,扛不住問不說,也不了解原理。所以,如果你想真的提升自己技能,還是要從根本搞定。

二、案例工程

為了更好的做源碼分析,我們將平時(shí)用的定時(shí)任務(wù)服務(wù)單獨(dú)抽離出來。工程下載,關(guān)注公眾號(hào):bugstack蟲洞棧,回復(fù):源碼分析

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、環(huán)境配置

  1. JDK 1.8
  2. IDEA 2019.3.1
  3. Spring 4.3.24.RELEASE
  4. quartz 2.3.2 {不同版本略有代碼差異}

四、源碼分析

<dependency>
    <groupId>org.quartz-scheduler</groupId>
    <artifactId>quartz</artifactId>
    <version>2.3.2</version>
</dependency>

依賴于Spring版本升級(jí)quartz選擇2.3.2,同時(shí)如果你如本文案例中所示使用xml配置任務(wù)。那么會(huì)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的默認(rèn)配置,很多初始化動(dòng)作都要從這里取得參數(shù),同樣你可以配置自己的配置文件。例如,當(dāng)你的任務(wù)很多時(shí),默認(rèn)初始化的10個(gè)線程組不滿足你的業(yè)務(wù)需求,就可以按需調(diào)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. 從一個(gè)簡單案例開始

平時(shí)我們使用Schedule基本都是注解或者xml配置文件,但是為了可以更簡單的分析代碼,我們從一個(gè)簡單的Demo入手,放到main函數(shù)中。

DemoTask.java & 定義一個(gè)等待被執(zhí)行的任務(wù)

public class DemoTask {

    private Logger logger = LoggerFactory.getLogger(DemoTask.class);

    public void execute() throws Exception{
        logger.info("定時(shí)處理用戶信息任務(wù):0/5 * * * * ?");
    }

}

MyTask.java & 測試類,將配置在xml中的代碼抽離出來

public class MyTask {

    public static void main(String[] args) throws Exception {

        DemoTask demoTask = new DemoTask();

        // 定義了;執(zhí)行的內(nèi)容
        MethodInvokingJobDetailFactoryBean methodInvokingJobDetailFactoryBean = new MethodInvokingJobDetailFactoryBean();
        methodInvokingJobDetailFactoryBean.setTargetObject(demoTask);
        methodInvokingJobDetailFactoryBean.setTargetMethod("execute");
        methodInvokingJobDetailFactoryBean.setConcurrent(true);
        methodInvokingJobDetailFactoryBean.setName("demoTask");
        methodInvokingJobDetailFactoryBean.afterPropertiesSet();

        // 定義了;執(zhí)行的計(jì)劃
        CronTriggerFactoryBean cronTriggerFactoryBean = new CronTriggerFactoryBean();
        cronTriggerFactoryBean.setJobDetail(methodInvokingJobDetailFactoryBean.getObject());
        cronTriggerFactoryBean.setCronExpression("0/5 * * * * ?");
        cronTriggerFactoryBean.setName("demoTask");
        cronTriggerFactoryBean.afterPropertiesSet();

        // 實(shí)現(xiàn)了;執(zhí)行的功能
        SchedulerFactoryBean schedulerFactoryBean = new SchedulerFactoryBean();
        schedulerFactoryBean.setTriggers(cronTriggerFactoryBean.getObject());
        schedulerFactoryBean.setAutoStartup(true);
        schedulerFactoryBean.afterPropertiesSet();

        schedulerFactoryBean.start();

        // 暫停住
        System.in.read();

    }

}

如果一切順利,那么會(huì)有如下結(jié)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] - 定時(shí)處理用戶信息任務(wù):0/5 * * * * ?
2020-01-04 10:47:25.001 [QuartzScheduler_Worker-2] INFO  org.itstack.demo.DemoTask[11] - 定時(shí)處理用戶信息任務(wù):0/5 * * * * ?
2020-01-04 10:47:30.000 [QuartzScheduler_Worker-3] INFO  org.itstack.demo.DemoTask[11] - 定時(shí)處理用戶信息任務(wù):0/5 * * * * ?
2020-01-04 10:47:35.001 [QuartzScheduler_Worker-4] INFO  org.itstack.demo.DemoTask[11] - 定時(shí)處理用戶信息任務(wù):0/5 * * * * ?
2020-01-04 10:47:40.000 [QuartzScheduler_Worker-5] INFO  org.itstack.demo.DemoTask[11] - 定時(shí)處理用戶信息任務(wù):0/5 * * * * ?

Process finished with exit code -1

2. 定義執(zhí)行內(nèi)容(MethodInvokingJobDetailFactoryBean)

// 定義了;執(zhí)行的內(nèi)容
MethodInvokingJobDetailFactoryBean methodInvokingJobDetailFactoryBean = new MethodInvokingJobDetailFactoryBean();
methodInvokingJobDetailFactoryBean.setTargetObject(demoTask);
methodInvokingJobDetailFactoryBean.setTargetMethod("execute");
methodInvokingJobDetailFactoryBean.setConcurrent(true);
methodInvokingJobDetailFactoryBean.setName("demoTask");
methodInvokingJobDetailFactoryBean.afterPropertiesSet();

這塊內(nèi)容主要將我們的任務(wù)體(即待執(zhí)行任務(wù)DemoTask)交給MethodInvokingJobDetailFactoryBean管理,首先設(shè)置必要信息;

  • targetObject:目標(biāo)對(duì)象bean,也就是demoTask
  • targetMethod:目標(biāo)方法name,也就是execute
  • concurrent:是否并行執(zhí)行,非并行執(zhí)行任務(wù),如果上一個(gè)任務(wù)沒有執(zhí)行完,下一刻不會(huì)執(zhí)行
  • name:xml配置非必傳,源碼中可以獲取beanName

最后我們通過手動(dòng)調(diào)用 afterPropertiesSet() 來模擬初始化。如果我們的類是交給 Spring 管理的,那么在實(shí)現(xiàn)了 InitializingBean 接口的類,在類配置信息加載后會(huì)自動(dòng)執(zhí)行 afterPropertiesSet() 。一般實(shí)現(xiàn)了 InitializingBean 接口的類,同時(shí)也會(huì)去實(shí)現(xiàn) FactoryBean 接口,因?yàn)檫@個(gè)接口實(shí)現(xiàn)后就可以通過 T getObject() 獲取自己自定義初始化的類。這也常常用在一些框架開發(fā)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);
}
  • 源碼168行: 根據(jù)是否并行執(zhí)行選擇任務(wù)類,這兩個(gè)類都是MethodInvokingJobDetailFactoryBean的內(nèi)部類,非并行執(zhí)行的StatefulMethodInvokingJob只是繼承MethodInvokingJob添加了標(biāo)記注解。

  • 源碼171行: 創(chuàng)建JobDetailImpl,添加任務(wù)明細(xì)信息,注意這類的jdi.setJobClass((Class) jobClass)實(shí)際就是MethodInvokingJob。MethodInvokingJob也是我們最終要反射調(diào)用執(zhí)行的內(nèi)容。

  • 源碼177行: 初始化任務(wù)后賦值給this.jobDetail = jdi,也就是最終的類對(duì)象

    MethodInvokingJobDetailFactoryBean.getObject()

    @Override
    public JobDetail getObject() {
    return this.jobDetail;
    }
    
  • 源碼:220行: 獲取對(duì)象時(shí)返回 this.jobDetail,這也就解釋了為什么 MethodInvokingJobDetailFactoryBean 初始化后直接賦值給了一個(gè) JobDetail ;

    微信公眾號(hào):bugstack蟲洞棧 & Schedule.xml

3. 定義執(zhí)行計(jì)劃(CronTriggerFactoryBeann)

// 定義了;執(zhí)行的計(jì)劃
CronTriggerFactoryBean cronTriggerFactoryBean = new CronTriggerFactoryBean();
cronTriggerFactoryBean.setJobDetail(methodInvokingJobDetailFactoryBean.getObject());
cronTriggerFactoryBean.setCronExpression("0/5 * * * * ?");
cronTriggerFactoryBean.setName("demoTask");
cronTriggerFactoryBean.afterPropertiesSet();

這一塊主要定義任務(wù)的執(zhí)行計(jì)劃,并將任務(wù)執(zhí)行內(nèi)容交給 CronTriggerFactoryBean 管理,同時(shí)設(shè)置必要信息;

  • jobDetail:設(shè)置任務(wù)體,xml 中可以直接將對(duì)象賦值,硬編碼中設(shè)置執(zhí)行的 JobDetail 對(duì)象信息。也就是我們上面設(shè)置的 JobDetailImpl ,通過 getObject() 獲取出來。
  • cronExpression:計(jì)劃表達(dá)式;秒、分、時(shí)、日、月、周、年

CronTriggerFactoryBean.afterPropertiesSet()

@Override
public void afterPropertiesSet() throws ParseException {
    
// ... 校驗(yàn)屬性信息

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;
}
  • 源碼237行: 創(chuàng)建觸發(fā)器 CronTriggerImpl 并設(shè)置相關(guān)屬性信息

  • 源碼245行: 生成執(zhí)行計(jì)劃類 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表達(dá)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();
    
    // ... 校驗(yàn)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++;
    }
    
    // ... 校驗(yàn)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表達(dá)式有7個(gè)字段,CronExpression 把7個(gè)字段解析為7個(gè) TreeSet 對(duì)象。
    • 填充TreeSet對(duì)象值的時(shí)候,表達(dá)式都會(huì)轉(zhuǎn)換為起始值、結(jié)束值和增量的計(jì)算模式,然后計(jì)算出匹配的值放進(jìn)TreeSet對(duì)象

CronTriggerFactoryBean.getObject()

@Override
public CronTrigger getObject() {
return this.cronTrigger;
}
  • 源碼257行: 獲取對(duì)象時(shí)返回 this.cronTrigger ,也就是 CronTriggerImpl 對(duì)象

4. 調(diào)度執(zhí)行計(jì)劃(SchedulerFactoryBean)

// 調(diào)度了;執(zhí)行的計(jì)劃(scheduler)
SchedulerFactoryBean schedulerFactoryBean = new SchedulerFactoryBean();
schedulerFactoryBean.setTriggers(cronTriggerFactoryBean.getObject());
schedulerFactoryBean.setAutoStartup(true);
schedulerFactoryBean.afterPropertiesSet();

schedulerFactoryBean.start();

這一部分如名字一樣調(diào)度工廠,相當(dāng)于一個(gè)指揮官,可以從全局做調(diào)度,比如監(jiān)聽哪些trigger已經(jīng)ready、分配線程等等,同樣也需要設(shè)置必要的屬性信息;

  • triggers:按需可以設(shè)置多個(gè)觸發(fā)器,本文設(shè)置了一個(gè) cronTriggerFactoryBean.getObject() 也就是 CronTriggerImpl 對(duì)象
  • autoStartup:默認(rèn)是否自動(dòng)啟動(dòng)任務(wù),默認(rèn)值為true

這個(gè)過程較長包括:調(diào)度工廠、線程池、注冊(cè)任務(wù)等等,整體核心加載流程如下;

微信公眾號(hào):bugstack蟲洞棧 & 調(diào)度工程初始化流程

  • 整個(gè)加載過程較長,抽取部分核心代碼塊進(jìn)行分析,其中包括的類;
    • 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;
}
}
  • 源碼474行: 為調(diào)度器做準(zhǔn)備工作 prepareScheduler(prepareSchedulerFactory()) ,依次執(zhí)行如下;

    1. SchedulerFactoryBean.prepareScheduler(SchedulerFactory schedulerFactory)
    2. SchedulerFactoryBean.createScheduler(schedulerFactory, this.schedulerName);
    3. SchedulerFactoryBean.createScheduler(SchedulerFactory schedulerFactory, String schedulerName)
    4. Scheduler newScheduler = schedulerFactory.getScheduler();
    5. StdSchedulerFactory.getScheduler();
    6. sched = instantiate(); 包括一系列核心操作;
    1)初始化threadPool(線程池):開發(fā)者可以通過org.quartz.threadPool.class配置指定使用哪個(gè)線程池類,比如SimpleThreadPool。
    2)初始化jobStore(任務(wù)存儲(chǔ)方式):開發(fā)者可以通過org.quartz.jobStore.class配置指定使用哪個(gè)任務(wù)存儲(chǔ)類,比如RAMJobStore。
    3)初始化dataSource(數(shù)據(jù)源):開發(fā)者可以通過org.quartz.dataSource配置指定數(shù)據(jù)源詳情,比如哪個(gè)數(shù)據(jù)庫、賬號(hào)、密碼等。
    4)初始化其他配置:包括SchedulerPlugins、JobListeners、TriggerListeners等;
    5)初始化threadExecutor(線程執(zhí)行器):默認(rèn)為DefaultThreadExecutor;
    6)創(chuàng)建工作線程:根據(jù)配置創(chuàng)建N個(gè)工作thread,執(zhí)行start()啟動(dòng)thread,并將N個(gè)thread順序add進(jìn)threadPool實(shí)例的空閑線程列表availWorkers中;
    7)創(chuàng)建調(diào)度器線程:創(chuàng)建QuartzSchedulerThread實(shí)例,并通過threadExecutor.execute(實(shí)例)啟動(dòng)調(diào)度器線程;
    8)創(chuàng)建調(diào)度器:創(chuàng)建StdScheduler實(shí)例,將上面所有配置和引用組合進(jìn)實(shí)例中,并將實(shí)例存入調(diào)度器池中
    
  • 源碼477行: 調(diào)用父類 SchedulerAccessor.registerJobsAndTriggers() 注冊(cè)任務(wù)和觸發(fā)器

    for (Trigger trigger : this.triggers) {
    addTriggerToScheduler(trigger);
    }
    

SchedulerAccessor.addTriggerToScheduler() & SchedulerAccessor 是SchedulerFactoryBean的父類

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;
}
  • 源碼299行: addJobToScheduler(jobDetail) 一直會(huì)調(diào)用到 RAMJobStore 進(jìn)行存放任務(wù)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
    }
    }
    }
    
  • 初始化線程組;

    • prepareScheduler
    • createScheduler
    • schedulerFactory
    • StdSchedulerFactory.getScheduler()
    • getScheduler()->instantiate()
    • 源碼1323行: tp.initialize();

    SimpleThreadPool.initialize() & 這里的count是默認(rèn)配置中的數(shù)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. 啟動(dòng)定時(shí)任務(wù)

案例中使用硬編碼方式調(diào)用 schedulerFactoryBean.start() 啟動(dòng)線程服務(wù)。線程的協(xié)作通過Object sigLock來實(shí)現(xiàn),關(guān)于sigLock.wait()方法都在QuartzSchedulerThread的run方法里面,所以sigLock喚醒的是只有線程QuartzSchedulerThread。核心流程如下;

微信公眾號(hào):bugstack蟲洞棧 & 調(diào)度啟動(dòng)流程

這個(gè)啟動(dòng)過程中,核心的代碼類,如下;

  • StdScheduler
  • QuartzScheduler
  • QuartzSchedulerThread
  • ThreadPool
  • RAMJobStore
  • CronTriggerImpl
  • JobRunShellFactory

QuartzScheduler.start() & 啟動(dòng)

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();
    }

    // 喚醒線程
schedThread.togglePause(false);

    getLog().info(
            "Scheduler " + resources.getUniqueIdentifier() + " started.");
    
    notifySchedulerListenersStarted();
}

QuartzSchedulerThread.run() & 執(zhí)行過程

@Override
public void run() {
    int acquiresFailed = 0;

// 只有調(diào)用了halt()方法,才會(huì)退出這個(gè)死循環(huán)
    while (!halted.get()) {
        try {

// 一、如果是暫停狀態(tài),則循環(huán)超時(shí)等待1000毫秒

            // wait a bit, if reading from job store is consistently failing (e.g. DB is down or restarting)..
           
    // 阻塞直到有空閑的線程可用并返回可用的數(shù)量
            int availThreadCount = qsRsrcs.getThreadPool().blockForAvailableThreads();
            if(availThreadCount > 0) {

                List<OperableTrigger> triggers;
                long now = System.currentTimeMillis();
                clearSignaledSchedulingChange();
                
try {
// 二、獲取acquire狀態(tài)的Trigger列表,也就是即將執(zhí)行的任務(wù)
                    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:獲取List第一個(gè)Trigger的下次觸發(fā)時(shí)刻
long triggerTime = triggers.get(0).getNextFireTime().getTime();
                    
// 四:獲取任務(wù)觸發(fā)集合
List<TriggerFiredResult> res = qsRsrcs.getJobStore().triggersFired(triggers);

// 五:設(shè)置Triggers為'executing'狀態(tài)
qsRsrcs.getJobStore().releaseAcquiredTrigger(triggers.get(i));
                    
// 六:創(chuàng)建JobRunShell
qsRsrcs.getJobRunShellFactory().createJobRunShell(bndle);

// 七:執(zhí)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;
}
  • 源碼391行: 創(chuàng)建JobRunShell,JobRunShell實(shí)例在initialize()方法就會(huì)把包含業(yè)務(wù)邏輯類的JobDetailImpl設(shè)置為它的成員屬性,為后面執(zhí)行業(yè)務(wù)邏輯代碼做準(zhǔn)備。執(zhí)行業(yè)務(wù)邏輯代碼在runInThread(shell)方法里面。

    QuartzSchedulerThread.run() & 部分代碼

    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;
    }
    
  • 源碼398行: qsRsrcs.getThreadPool().runInThread(shell)

    SimpleThreadPool.runInThread

    // 保存所有WorkerThread的集合
    private List<WorkerThread> workers;
    // 空閑的WorkerThread集合
    private LinkedList<WorkerThread> availWorkers = new LinkedList<WorkerThread>();
    // 任務(wù)的WorkerThread集合
    private LinkedList<WorkerThread> busyWorkers = new LinkedList<WorkerThread>();
    
    /**
     * 維護(hù)workers、availWorkers和busyWorkers三個(gè)列表數(shù)據(jù)
     * 有任務(wù)需要一個(gè)線程出來執(zhí)行:availWorkers.removeFirst();busyWorkers.add()
     * 然后調(diào)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;
    }
    
  • 源碼428行: WorkerThread ,是一個(gè)內(nèi)部類,主要是賦值并喚醒lock對(duì)象的等待線程隊(duì)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();
    }
    }
    
  • 源碼561行: WorkerThread 的run方法,方法執(zhí)行l(wèi)ock.notifyAll()后,對(duì)應(yīng)的WorkerThread就會(huì)來到run()方法。到這!接近曙光了!終于來到了執(zhí)行業(yè)務(wù)的execute()方法的倒數(shù)第二步,runnable對(duì)象是一個(gè)JobRunShell對(duì)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;
    // 啟動(dòng)真正執(zhí)行的內(nèi)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() & 從上面WorkerThread.run(),調(diào)用到這里執(zhí)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());
                
// 執(zhí)行業(yè)務(wù)代碼,也就是我們的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);

            // 其他代碼
        } while (true);

    } finally {
        qs.removeInternalSchedulerListener(this);
    }
}

QuartzJobBean.execte() & 繼續(xù)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 {
// 反射執(zhí)行業(yè)務(wù)代碼
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、綜上總結(jié)

  • quartz,即石英的意思,隱喻如石英鐘般對(duì)時(shí)間的準(zhǔn)確把握。
  • 源碼分析是一個(gè)很快樂的過程,這個(gè)快樂是分析完才能獲得的快樂。縱橫交互的背后是面向?qū)ο蟮母叨冉怦?#xff0c;對(duì)線程精彩的使用,將任務(wù)執(zhí)行做成計(jì)劃單,簡直是一個(gè)超級(jí)棒的作品。
  • 對(duì)于quartz.properties,簡單場景下,開發(fā)者不用自定義配置,使用quartz默認(rèn)配置即可,但在要求較高的使用場景中還是要自定義配置,比如通過org.quartz.threadPool.threadCount設(shè)置足夠的線程數(shù)可提高多job場景下的運(yùn)行性能。
  • quartz 對(duì)任務(wù)處理高度解耦,job與trigger解藕,將任務(wù)本身和任務(wù)執(zhí)行策略解藕,這樣可以方便實(shí)現(xiàn)N個(gè)任務(wù)和M個(gè)執(zhí)行策略自由組合。
  • scheduler單獨(dú)分離出來,相當(dāng)于一個(gè)指揮官,可以從全局做調(diào)度,比如監(jiān)聽哪些trigger已經(jīng)ready、分配線程等等。
  • 外部鏈接:
    • http://www.
    • quartz-2.1.x/configuration

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