quartz集群调度任务负载不均

问题:

多台服务集群模式执行调度周期短的任务不能均衡负载。

原因:

下面的run()方法中,不考虑halted和siglock的情况下1)只有if (triggers != null && !triggers.isEmpty())条件满足的情况下,while循环才会进入暂停状态sigLock.wait(timeUntilContinue);2)并且获取待执行trigger时最终执行的sql以及传入的条件如下,即next fire time范围为:

QuartzSchedulerThread.java
triggers = qsRsrcs.getJobStore().acquireNextTriggers(
                                now + idleWaitTime, Math.min(availThreadCount, qsRsrcs.getMaxBatchSize()), qsRsrcs.getBatchTimeWindow());
JobStoreSupport.java 
List<TriggerKey> keys = getDelegate().selectTriggerToAcquire(conn, noLaterThan + timeWindow, getMisfireTime(), maxCount);

protected long getMisfireTime() {
        long misfireTime = System.currentTimeMillis();
        if (getMisfireThreshold() > 0) {
            misfireTime -= getMisfireThreshold();
        }
        return (misfireTime > 0) ? misfireTime : 0;
    }
public long getMisfireThreshold() {
        return misfireThreshold;
    }

String SELECT_NEXT_TRIGGER_TO_ACQUIRE = "SELECT "
        + COL_TRIGGER_NAME + ", " + COL_TRIGGER_GROUP + ", "
        + COL_NEXT_FIRE_TIME + ", " + COL_PRIORITY + " FROM "
        + TABLE_PREFIX_SUBST + TABLE_TRIGGERS + " WHERE "
        + COL_SCHEDULER_NAME + " = " + SCHED_NAME_SUBST
        + " AND " + COL_TRIGGER_STATE + " = ? AND " + COL_NEXT_FIRE_TIME + " <= ? " 
        + "AND (" + COL_MISFIRE_INSTRUCTION + " = -1 OR (" +COL_MISFIRE_INSTRUCTION+ " != -1 AND "+ COL_NEXT_FIRE_TIME + " >= ?)) "
        + "ORDER BY "+ COL_NEXT_FIRE_TIME + " ASC, " + COL_PRIORITY + " DESC";

与查询条件相关的参数:

Variable Property Name Default Value
idleWaitTime org.quartz.scheduler.idleWaitTime 30000L
maxBatchSize org.quartz.scheduler.batchTriggerAcquisitionMaxCount 1
batchTimeWindow org.quartz.scheduler.batchTriggerAcquisitionFireAheadTimeWindow 0
misfireThreshold 60000L; // one minute

所以只有run方法中的while暂停,不去获取新的trigger时其他服务才有机会拿到执行任务,以达到负载均衡。

QuartzSchedulerThread.java
public void run() {
        int acquiresFailed = 0;

        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) {
                        }

                        // reset failure counter when paused, so that we don't
                        // wait again after unpausing
                        acquiresFailed = 0;
                    }

                    if (halted.get()) {
                        break;
                    }
                }

                // wait a bit, if reading from job store is consistently
                // failing (e.g. DB is down or restarting)..
                if (acquiresFailed > 1) {
                    try {
                        long delay = computeDelayForRepeatedErrors(qsRsrcs.getJobStore(), acquiresFailed);
                        Thread.sleep(delay);
                    } catch (Exception ignore) {
                    }
                }

                int availThreadCount = qsRsrcs.getThreadPool().blockForAvailableThreads();
                if(availThreadCount > 0) { // will always be true, due to semantics of blockForAvailableThreads...

                    List<OperableTrigger> triggers;

                    long now = System.currentTimeMillis();

                    clearSignaledSchedulingChange();
                    try {
                        triggers = qsRsrcs.getJobStore().acquireNextTriggers(
                                now + idleWaitTime, Math.min(availThreadCount, qsRsrcs.getMaxBatchSize()), qsRsrcs.getBatchTimeWindow());
                        acquiresFailed = 0;
                        if (log.isDebugEnabled())
                            log.debug("batch acquisition of " + (triggers == null ? 0 : triggers.size()) + " triggers");
                    } catch (JobPersistenceException jpe) {
                        if (acquiresFailed == 0) {
                            qs.notifySchedulerListenersError(
                                "An error occurred while scanning for the next triggers to fire.",
                                jpe);
                        }
                        if (acquiresFailed < Integer.MAX_VALUE)
                            acquiresFailed++;
                        continue;
                    } catch (RuntimeException e) {
                        if (acquiresFailed == 0) {
                            getLog().error("quartzSchedulerThreadLoop: RuntimeException "
                                    +e.getMessage(), e);
                        }
                        if (acquiresFailed < Integer.MAX_VALUE)
                            acquiresFailed++;
                        continue;
                    }

                    if (triggers != null && !triggers.isEmpty()) {

                        now = System.currentTimeMillis();
                        long triggerTime = triggers.get(0).getNextFireTime().getTime();
                        long timeUntilTrigger = triggerTime - now;
                        while(timeUntilTrigger > 2) {
                            synchronized (sigLock) {
                                if (halted.get()) {
                                    break;
                                }
                                if (!isCandidateNewTimeEarlierWithinReason(triggerTime, false)) {
                                    try {
                                        // we could have blocked a long while
                                        // on 'synchronize', so we must recompute
                                        now = System.currentTimeMillis();
                                        timeUntilTrigger = triggerTime - now;
                                        if(timeUntilTrigger >= 1)
                                            sigLock.wait(timeUntilTrigger);
                                    } catch (InterruptedException ignore) {
                                    }
                                }
                            }
                            if(releaseIfScheduleChangedSignificantly(triggers, triggerTime)) {
                                break;
                            }
                            now = System.currentTimeMillis();
                            timeUntilTrigger = triggerTime - now;
                        }

                        // this happens if releaseIfScheduleChangedSignificantly decided to release triggers
                        if(triggers.isEmpty())
                            continue;

                        // set triggers to 'executing'
                        List<TriggerFiredResult> bndles = new ArrayList<TriggerFiredResult>();

                        boolean goAhead = true;
                        synchronized(sigLock) {
                            goAhead = !halted.get();
                        }
                        if(goAhead) {
                            try {
                                List<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 again
                                for (int i = 0; i < triggers.size(); i++) {
                                    qsRsrcs.getJobStore().releaseAcquiredTrigger(triggers.get(i));
                                }
                                continue;
                            }

                        }

                        for (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)
                            if (bndle == null) {
                                qsRsrcs.getJobStore().releaseAcquiredTrigger(triggers.get(i));
                                continue;
                            }

                            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;
                            }

                            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 contract
                    continue; // while (!halted)
                }

                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 soon
                        if (!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;
    }

其他:

https://www.quartz-scheduler.org/documentation/quartz-2.3.0/tutorials/tutorial-lesson-11.html

转载于:https://www.jianshu.com/p/4c98233e7d06

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转载自blog.csdn.net/weixin_33781606/article/details/91280807