public class HelloWorldMain {Log log = LogFactory.getLog(HelloWorldMain.class);public void run() {try {//取得Schedule对象SchedulerFactory sf = new StdSchedulerFactory();Scheduler sch = sf.getScheduler(); JobDetail jd = new JobDetail("HelloWorldJobDetail",Scheduler.DEFAULT_GROUP,HelloWorldJob.class);Trigger tg = TriggerUtils.makeMinutelyTrigger(1);tg.setName("HelloWorldTrigger");sch.scheduleJob(jd, tg);sch.start();} catch ( Exception e ) {e.printStackTrace();}}public static void main(String[] args) {HelloWorldMain hw = new HelloWorldMain();hw.run();}
}

public Scheduler getScheduler() throws SchedulerException {if (cfg == null) {initialize();}SchedulerRepository schedRep = SchedulerRepository.getInstance();//从"调度器仓库"中根据properties的SchedulerName配置获取一个调度器实例Scheduler sched = schedRep.lookup(getSchedulerName());if (sched != null) {if (sched.isShutdown()) {schedRep.remove(getSchedulerName());} else {return sched;}}//初始化调度器sched = instantiate();return sched;}

public void initialize(ClassLoadHelper loadHelper,SchedulerSignaler signaler) throws SchedulerConfigException {if (dsName == null) {throw new SchedulerConfigException("DataSource name not set.");}classLoadHelper = loadHelper;if(isThreadsInheritInitializersClassLoadContext()) {log.info("JDBCJobStore threads will inherit ContextClassLoader of thread: " + Thread.currentThread().getName());initializersLoader = Thread.currentThread().getContextClassLoader();}this.schedSignaler = signaler;// If the user hasn't specified an explicit lock handler, then// choose one based on CMT/Clustered/UseDBLocks.if (getLockHandler() == null) {// If the user hasn't specified an explicit lock handler,// then we *must* use DB locks with clusteringif (isClustered()) {setUseDBLocks(true);}if (getUseDBLocks()) {if(getDriverDelegateClass() != null && getDriverDelegateClass().equals(MSSQLDelegate.class.getName())) {if(getSelectWithLockSQL() == null) {//读取数据库LOCKS表中对应当前调度器的锁信息String msSqlDflt = "SELECT * FROM {0}LOCKS WITH (UPDLOCK,ROWLOCK) WHERE " + COL_SCHEDULER_NAME + " = {1} AND LOCK_NAME = ?";getLog().info("Detected usage of MSSQLDelegate class - defaulting 'selectWithLockSQL' to '" + msSqlDflt + "'.");setSelectWithLockSQL(msSqlDflt);}}getLog().info("Using db table-based data access locking (synchronization).");setLockHandler(new StdRowLockSemaphore(getTablePrefix(), getInstanceName(), getSelectWithLockSQL()));} else {getLog().info("Using thread monitor-based data access locking (synchronization).");setLockHandler(new SimpleSemaphore());}}}

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()//通知该调度器的listener启动开始
        notifySchedulerListenersStarting();if (initialStart == null) {initialStart = new Date();//启动调度器的线程this.resources.getJobStore().schedulerStarted();            //启动plugins
            startPlugins();} else {resources.getJobStore().schedulerResumed();}schedThread.togglePause(false);getLog().info("Scheduler " + resources.getUniqueIdentifier() + " started.");//通知该调度器的listener启动完成
        notifySchedulerListenersStarted();}

public void run() {boolean lastAcquireFailed = false;//
        while (!halted.get()) {try {// check if we're supposed to pause...synchronized (sigLock) {while (paused && !halted.get()) {try {// wait until togglePause(false) is called...sigLock.wait(1000L);} catch (InterruptedException ignore) {}}if (halted.get()) {break;}}/获取当前线程池中线程的数量int availThreadCount = qsRsrcs.getThreadPool().blockForAvailableThreads();if(availThreadCount > 0) { // will always be true, due to semantics of blockForAvailableThreads...List<OperableTrigger> triggers = null;long now = System.currentTimeMillis();clearSignaledSchedulingChange();try {//调度器在trigger队列中寻找30秒内一定数目的trigger准备执行调度,//参数1:nolaterthan = now+3000ms,参数2 最大获取数量,大小取线程池线程剩余量与定义值得较小者//参数3 时间窗口 默认为0,程序会在nolaterthan后加上窗口大小来选择triggertriggers = qsRsrcs.getJobStore().acquireNextTriggers(now + idleWaitTime, Math.min(availThreadCount, qsRsrcs.getMaxBatchSize()), qsRsrcs.getBatchTimeWindow());//上一步获取成功将失败标志置为false;lastAcquireFailed = false;if (log.isDebugEnabled())log.debug("batch acquisition of " + (triggers == null ? 0 : triggers.size()) + " triggers");} catch (JobPersistenceException jpe) {if(!lastAcquireFailed) {qs.notifySchedulerListenersError("An error occurred while scanning for the next triggers to fire.",jpe);}//捕捉到异常则值标志为true,再次尝试获取lastAcquireFailed = true;continue;} catch (RuntimeException e) {if(!lastAcquireFailed) {getLog().error("quartzSchedulerThreadLoop: RuntimeException "+e.getMessage(), e);}lastAcquireFailed = true;continue;}if (triggers != null && !triggers.isEmpty()) {now = System.currentTimeMillis();long triggerTime = triggers.get(0).getNextFireTime().getTime();long timeUntilTrigger = triggerTime - now;//计算距离trigger触发的时间while(timeUntilTrigger > 2) {synchronized (sigLock) {if (halted.get()) {break;}//如果这时调度器发生了改变,新的trigger添加进来,那么有可能新添加的trigger比当前待执行的trigger//更急迫,那么需要放弃当前trigger重新获取,然而,这里存在一个值不值得的问题,如果重新获取新trigger//的时间要长于当前时间到新trigger出发的时间,那么即使放弃当前的trigger,仍然会导致xntrigger获取失败,//但我们又不知道获取新的trigger需要多长时间,于是,我们做了一个主观的评判,若jobstore为RAM,那么//假定获取时间需要7ms,若jobstore是持久化的,假定其需要70ms,当前时间与新trigger的触发时间之差小于// 这个值的我们认为不值得重新获取,返回false//这里判断是否有上述情况发生,值不值得放弃本次trigger,若判定不放弃,则线程直接等待至trigger触发的时刻if (!isCandidateNewTimeEarlierWithinReason(triggerTime, false)) {try {// we could have blocked a long while// on 'synchronize', so we must recomputenow = System.currentTimeMillis();timeUntilTrigger = triggerTime - now;if(timeUntilTrigger >= 1)sigLock.wait(timeUntilTrigger);} catch (InterruptedException ignore) {}}}//该方法调用了上面的判定方法,作为再次判定的逻辑//到达这里有两种情况1.决定放弃当前trigger,那么再判定一次,如果仍然有放弃,那么清空triggers列表并// 退出循环 2.不放弃当前trigger,且线程已经wait到trigger触发的时刻,那么什么也不做if(releaseIfScheduleChangedSignificantly(triggers, triggerTime)) {break;}now = System.currentTimeMillis();timeUntilTrigger = triggerTime - now;//这时触发器已经即将触发,值会<2
                        }// this happens if releaseIfScheduleChangedSignificantly decided to release triggersif(triggers.isEmpty())continue;// set triggers to 'executing'List<TriggerFiredResult> bndles = new ArrayList<TriggerFiredResult>();boolean goAhead = true;synchronized(sigLock) {goAhead = !halted.get();}if(goAhead) {try {//触发triggers,结果付给bndles,注意,从这里返回后,trigger在数据库中已经经过了锁定,解除锁定,这一套过程//所以说,quratz定不是等到job执行完才释放trigger资源的占有,而是读取完本次触发所需的信息后立即释放资源//然后再执行jobsList<TriggerFiredResult> res = qsRsrcs.getJobStore().triggersFired(triggers);if(res != null)bndles = res;} catch (SchedulerException se) {qs.notifySchedulerListenersError("An error occurred while firing triggers '"+ triggers + "'", se);//QTZ-179 : a problem occurred interacting with the triggers from the db//we release them and loop againfor (int i = 0; i < triggers.size(); i++) {qsRsrcs.getJobStore().releaseAcquiredTrigger(triggers.get(i));}continue;}}//迭代trigger的信息,分别跑jobfor (int i = 0; i < bndles.size(); i++) {TriggerFiredResult result =  bndles.get(i);TriggerFiredBundle bndle =  result.getTriggerFiredBundle();Exception exception = result.getException();if (exception instanceof RuntimeException) {getLog().error("RuntimeException while firing trigger " + triggers.get(i), exception);qsRsrcs.getJobStore().releaseAcquiredTrigger(triggers.get(i));continue;}// it's possible to get 'null' if the triggers was paused,// blocked, or other similar occurrences that prevent it being// fired at this time...  or if the scheduler was shutdown (halted)//在特殊情况下,bndle可能为null,看triggerFired方法可以看到,当从数据库获取trigger时,如果status不是//STATE_ACQUIRED,那么会直接返回空.quratz这种情况下本调度器启动重试流程,重新获取4次,若仍有问题,// 则抛出异常.if (bndle == null) {qsRsrcs.getJobStore().releaseAcquiredTrigger(triggers.get(i));continue;}//执行jobJobRunShell shell = null;try {//创建一个job的Runshellshell = 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;}//把runShell放在线程池里跑if (qsRsrcs.getThreadPool().runInThread(shell) == false) {// this case should never happen, as it is indicative of the// scheduler being shutdown or a bug in the thread pool or// a thread pool being used concurrently - which the docs// say not to do...getLog().error("ThreadPool.runInThread() return false!");qsRsrcs.getJobStore().triggeredJobComplete(triggers.get(i), bndle.getJobDetail(), CompletedExecutionInstruction.SET_ALL_JOB_TRIGGERS_ERROR);}}continue; // while (!halted)
                    }} else { // if(availThreadCount > 0)// should never happen, if threadPool.blockForAvailableThreads() follows contractcontinue; // while (!halted)
                }//保证负载平衡的方法,每次执行一轮触发后,本scheduler会等待一个随机的时间,这样就使得其他节点上的scheduler可以得到资源.long now = System.currentTimeMillis();long waitTime = now + getRandomizedIdleWaitTime();long timeUntilContinue = waitTime - now;synchronized(sigLock) {try {if(!halted.get()) {// QTZ-336 A job might have been completed in the mean time and we might have// missed the scheduled changed signal by not waiting for the notify() yet// Check that before waiting for too long in case this very job needs to be// scheduled very soonif (!isScheduleChanged()) {sigLock.wait(timeUntilContinue);}}} catch (InterruptedException ignore) {}}} catch(RuntimeException re) {getLog().error("Runtime error occurred in main trigger firing loop.", re);}} // while (!halted)// drop references to scheduler stuff to aid garbage collection...qs = null;qsRsrcs = null;}

public List<OperableTrigger> acquireNextTriggers(final long noLaterThan, final int maxCount, final long timeWindow)throws JobPersistenceException {String lockName;if(isAcquireTriggersWithinLock() || maxCount > 1) {lockName = LOCK_TRIGGER_ACCESS;} else {lockName = null;}return executeInNonManagedTXLock(lockName,new TransactionCallback<List<OperableTrigger>>() {public List<OperableTrigger> execute(Connection conn) throws JobPersistenceException {return acquireNextTrigger(conn, noLaterThan, maxCount, timeWindow);}},new TransactionValidator<List<OperableTrigger>>() {public Boolean validate(Connection conn, List<OperableTrigger> result) throws JobPersistenceException {//...异常处理回调方法
                    }});}

public List<TriggerFiredResult> triggersFired(final List<OperableTrigger> triggers) throws JobPersistenceException {return executeInNonManagedTXLock(LOCK_TRIGGER_ACCESS,new TransactionCallback<List<TriggerFiredResult>>() {public List<TriggerFiredResult> execute(Connection conn) throws JobPersistenceException {List<TriggerFiredResult> results = new ArrayList<TriggerFiredResult>();TriggerFiredResult result;for (OperableTrigger trigger : triggers) {try {TriggerFiredBundle bundle = triggerFired(conn, trigger);result = new TriggerFiredResult(bundle);} catch (JobPersistenceException jpe) {result = new TriggerFiredResult(jpe);} catch(RuntimeException re) {result = new TriggerFiredResult(re);}results.add(result);}return results;}},new TransactionValidator<List<TriggerFiredResult>>() {@Overridepublic Boolean validate(Connection conn, List<TriggerFiredResult> result) throws JobPersistenceException {//...异常处理回调方法
                    }});}

protected TriggerFiredBundle triggerFired(Connection conn,OperableTrigger trigger)throws JobPersistenceException {JobDetail job;Calendar cal = null;// Make sure trigger wasn't deleted, paused, or completed...try { // if trigger was deleted, state will be STATE_DELETEDString state = getDelegate().selectTriggerState(conn,trigger.getKey());if (!state.equals(STATE_ACQUIRED)) {return null;}} catch (SQLException e) {throw new JobPersistenceException("Couldn't select trigger state: "+ e.getMessage(), e);}try {job = retrieveJob(conn, trigger.getJobKey());if (job == null) { return null; }} catch (JobPersistenceException jpe) {try {getLog().error("Error retrieving job, setting trigger state to ERROR.", jpe);getDelegate().updateTriggerState(conn, trigger.getKey(),STATE_ERROR);} catch (SQLException sqle) {getLog().error("Unable to set trigger state to ERROR.", sqle);}throw jpe;}if (trigger.getCalendarName() != null) {cal = retrieveCalendar(conn, trigger.getCalendarName());if (cal == null) { return null; }}try {getDelegate().updateFiredTrigger(conn, trigger, STATE_EXECUTING, job);} catch (SQLException e) {throw new JobPersistenceException("Couldn't insert fired trigger: "+ e.getMessage(), e);}Date prevFireTime = trigger.getPreviousFireTime();// call triggered - to update the trigger's next-fire-time state...
        trigger.triggered(cal);String state = STATE_WAITING;boolean force = true;if (job.isConcurrentExectionDisallowed()) {state = STATE_BLOCKED;force = false;try {getDelegate().updateTriggerStatesForJobFromOtherState(conn, job.getKey(),STATE_BLOCKED, STATE_WAITING);getDelegate().updateTriggerStatesForJobFromOtherState(conn, job.getKey(),STATE_BLOCKED, STATE_ACQUIRED);getDelegate().updateTriggerStatesForJobFromOtherState(conn, job.getKey(),STATE_PAUSED_BLOCKED, STATE_PAUSED);} catch (SQLException e) {throw new JobPersistenceException("Couldn't update states of blocked triggers: "+ e.getMessage(), e);}}if (trigger.getNextFireTime() == null) {state = STATE_COMPLETE;force = true;}storeTrigger(conn, trigger, job, true, state, force, false);job.getJobDataMap().clearDirtyFlag();return new TriggerFiredBundle(job, trigger, cal, trigger.getKey().getGroup().equals(Scheduler.DEFAULT_RECOVERY_GROUP), new Date(), trigger.getPreviousFireTime(), prevFireTime, trigger.getNextFireTime());}

3.
select TRIGGER_ACCESS from QRTZ2_LOCKS for update
4.
SELECT TRIGGER_NAME,
TRIGGER_GROUP,
NEXT_FIRE_TIME,
PRIORITY
FROM QRTZ2_TRIGGERS
WHERE SCHEDULER_NAME = 'CRMscheduler'
AND TRIGGER_STATE = 'ACQUIRED'
AND NEXT_FIRE_TIME <= '{timekey 30s latter}'
AND ( MISFIRE_INSTR = -1
OR ( MISFIRE_INSTR != -1
AND NEXT_FIRE_TIME >= '{timekey now}' ) )
ORDER BY NEXT_FIRE_TIME ASC,
PRIORITY DESC;
5.
SELECT *
FROM QRTZ2_JOB_DETAILS
WHERE SCHEDULER_NAME = CRMscheduler
AND JOB_NAME = ?
AND JOB_GROUP = ?;
6.
UPDATE TQRTZ2_TRIGGERS
SET TRIGGER_STATE = 'ACQUIRED'
WHERE SCHED_NAME = 'CRMscheduler'
AND TRIGGER_NAME = '{triggerName}'
AND TRIGGER_GROUP = '{triggerGroup}'
AND TRIGGER_STATE = 'waiting';
7.
INSERT INTO QRTZ2_FIRED_TRIGGERS
(SCHEDULER_NAME,
ENTRY_ID,
TRIGGER_NAME,
TRIGGER_GROUP,
INSTANCE_NAME,
FIRED_TIME,
SCHED_TIME,
STATE,
JOB_NAME,
JOB_GROUP,
IS_NONCONCURRENT,
REQUESTS_RECOVERY,
PRIORITY)
VALUES( 'CRMscheduler', ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?);
8.
commit;
12.
select STAT_ACCESS from QRTZ2_LOCKS for update
13.
SELECT TRIGGER_STATE FROM QRTZ2_TRIGGERS WHERE SCHEDULER_NAME = 'CRMscheduler' AND TRIGGER_NAME = ? AND TRIGGER_GROUP = ?;
14.
SELECT TRIGGER_STATE
FROM QRTZ2_TRIGGERS
WHERE SCHEDULER_NAME = 'CRMscheduler'
AND TRIGGER_NAME = ?
AND TRIGGER_GROUP = ?;
14.
SELECT *
FROM QRTZ2_JOB_DETAILS
WHERE SCHEDULER_NAME = CRMscheduler
AND JOB_NAME = ?
AND JOB_GROUP = ?;
15.
SELECT *
FROM QRTZ2_CALENDARS
WHERE SCHEDULER_NAME = 'CRMscheduler'
AND CALENDAR_NAME = ?;
16.
UPDATE QRTZ2_FIRED_TRIGGERS
SET INSTANCE_NAME = ?,
FIRED_TIME = ?,
SCHED_TIME = ?,
ENTRY_STATE = ?,
JOB_NAME = ?,
JOB_GROUP = ?,
IS_NONCONCURRENT = ?,
REQUESTS_RECOVERY = ?
WHERE SCHEDULER_NAME = 'CRMscheduler'
AND ENTRY_ID = ?;
17.
UPDATE TQRTZ2_TRIGGERS
SET TRIGGER_STATE = ?
WHERE SCHED_NAME = 'CRMscheduler'
AND TRIGGER_NAME = '{triggerName}'
AND TRIGGER_GROUP = '{triggerGroup}'
AND TRIGGER_STATE = ？;
18.
UPDATE QRTZ2_TRIGGERS
SET JOB_NAME = ?,
JOB_GROUP = ?,
DESCRIPTION = ?,
NEXT_FIRE_TIME = ?,
PREV_FIRE_TIME = ?,
TRIGGER_STATE = ?,
TRIGGER_TYPE = ?,
START_TIME = ?,
END_TIME = ?,
CALENDAR_NAME = ?,
MISFIRE_INSTRUCTION = ?,
PRIORITY = ?,
JOB_DATAMAP = ?
WHERE SCHEDULER_NAME = SCHED_NAME_SUBST
AND TRIGGER_NAME = ?
AND TRIGGER_GROUP = ?;
19.
commit;