聊聊Elasticsearch的MonitorService

序

本文主要研究一下Elasticsearch的MonitorService

MonitorService

elasticsearch-7.0.1/server/src/main/java/org/elasticsearch/monitor/MonitorService.java

public class MonitorService extends AbstractLifecycleComponent {

    private final JvmGcMonitorService jvmGcMonitorService;
    private final OsService osService;
    private final ProcessService processService;
    private final JvmService jvmService;
    private final FsService fsService;

    public MonitorService(Settings settings, NodeEnvironment nodeEnvironment, ThreadPool threadPool,
                          ClusterInfoService clusterInfoService) throws IOException {
        this.jvmGcMonitorService = new JvmGcMonitorService(settings, threadPool);
        this.osService = new OsService(settings);
        this.processService = new ProcessService(settings);
        this.jvmService = new JvmService(settings);
        this.fsService = new FsService(settings, nodeEnvironment, clusterInfoService);
    }

    public OsService osService() {
        return this.osService;
    }

    public ProcessService processService() {
        return this.processService;
    }

    public JvmService jvmService() {
        return this.jvmService;
    }

    public FsService fsService() {
        return this.fsService;
    }

    @Override
    protected void doStart() {
        jvmGcMonitorService.start();
    }

    @Override
    protected void doStop() {
        jvmGcMonitorService.stop();
    }

    @Override
    protected void doClose() {
        jvmGcMonitorService.close();
    }

}

• MonitorService的构造器创建了jvmGcMonitorService、osService、processService、jvmService、fsService；其doStart、doStop、doClose分别调用了jvmGcMonitorService的start、stop、close方法

JvmGcMonitorService

elasticsearch-7.0.1/server/src/main/java/org/elasticsearch/monitor/jvm/JvmGcMonitorService.java

public class JvmGcMonitorService extends AbstractLifecycleComponent {
    private static final Logger logger = LogManager.getLogger(JvmGcMonitorService.class);

    private final ThreadPool threadPool;
    private final boolean enabled;
    private final TimeValue interval;
    private final Map<String, GcThreshold> gcThresholds;
    private final GcOverheadThreshold gcOverheadThreshold;

    private volatile Cancellable scheduledFuture;

    public static final Setting<Boolean> ENABLED_SETTING =
        Setting.boolSetting("monitor.jvm.gc.enabled", true, Property.NodeScope);
    public static final Setting<TimeValue> REFRESH_INTERVAL_SETTING =
        Setting.timeSetting("monitor.jvm.gc.refresh_interval", TimeValue.timeValueSeconds(1), TimeValue.timeValueSeconds(1),
            Property.NodeScope);

    private static String GC_COLLECTOR_PREFIX = "monitor.jvm.gc.collector.";
    public static final Setting<Settings> GC_SETTING = Setting.groupSetting(GC_COLLECTOR_PREFIX, Property.NodeScope);

    public static final Setting<Integer> GC_OVERHEAD_WARN_SETTING =
        Setting.intSetting("monitor.jvm.gc.overhead.warn", 50, 0, 100, Property.NodeScope);
    public static final Setting<Integer> GC_OVERHEAD_INFO_SETTING =
        Setting.intSetting("monitor.jvm.gc.overhead.info", 25, 0, 100, Property.NodeScope);
    public static final Setting<Integer> GC_OVERHEAD_DEBUG_SETTING =
        Setting.intSetting("monitor.jvm.gc.overhead.debug", 10, 0, 100, Property.NodeScope);

    //......

    public JvmGcMonitorService(Settings settings, ThreadPool threadPool) {
        this.threadPool = threadPool;

        this.enabled = ENABLED_SETTING.get(settings);
        this.interval = REFRESH_INTERVAL_SETTING.get(settings);

        Map<String, GcThreshold> gcThresholds = new HashMap<>();
        Map<String, Settings> gcThresholdGroups = GC_SETTING.get(settings).getAsGroups();
        for (Map.Entry<String, Settings> entry : gcThresholdGroups.entrySet()) {
            String name = entry.getKey();
            TimeValue warn = getValidThreshold(entry.getValue(), entry.getKey(), "warn");
            TimeValue info = getValidThreshold(entry.getValue(), entry.getKey(), "info");
            TimeValue debug = getValidThreshold(entry.getValue(), entry.getKey(), "debug");
            gcThresholds.put(name, new GcThreshold(name, warn.millis(), info.millis(), debug.millis()));
        }
        gcThresholds.putIfAbsent(GcNames.YOUNG, new GcThreshold(GcNames.YOUNG, 1000, 700, 400));
        gcThresholds.putIfAbsent(GcNames.OLD, new GcThreshold(GcNames.OLD, 10000, 5000, 2000));
        gcThresholds.putIfAbsent("default", new GcThreshold("default", 10000, 5000, 2000));
        this.gcThresholds = unmodifiableMap(gcThresholds);

        if (GC_OVERHEAD_WARN_SETTING.get(settings) <= GC_OVERHEAD_INFO_SETTING.get(settings)) {
            final String message =
                String.format(
                    Locale.ROOT,
                    "[%s] must be greater than [%s] [%d] but was [%d]",
                    GC_OVERHEAD_WARN_SETTING.getKey(),
                    GC_OVERHEAD_INFO_SETTING.getKey(),
                    GC_OVERHEAD_INFO_SETTING.get(settings),
                    GC_OVERHEAD_WARN_SETTING.get(settings));
            throw new IllegalArgumentException(message);
        }
        if (GC_OVERHEAD_INFO_SETTING.get(settings) <= GC_OVERHEAD_DEBUG_SETTING.get(settings)) {
            final String message =
                String.format(
                    Locale.ROOT,
                    "[%s] must be greater than [%s] [%d] but was [%d]",
                    GC_OVERHEAD_INFO_SETTING.getKey(),
                    GC_OVERHEAD_DEBUG_SETTING.getKey(),
                    GC_OVERHEAD_DEBUG_SETTING.get(settings),
                    GC_OVERHEAD_INFO_SETTING.get(settings));
            throw new IllegalArgumentException(message);
        }

        this.gcOverheadThreshold = new GcOverheadThreshold(
            GC_OVERHEAD_WARN_SETTING.get(settings),
            GC_OVERHEAD_INFO_SETTING.get(settings),
            GC_OVERHEAD_DEBUG_SETTING.get(settings));

        logger.debug(
            "enabled [{}], interval [{}], gc_threshold [{}], overhead [{}, {}, {}]",
            this.enabled,
            this.interval,
            this.gcThresholds,
            this.gcOverheadThreshold.warnThreshold,
            this.gcOverheadThreshold.infoThreshold,
            this.gcOverheadThreshold.debugThreshold);
    }

    @Override
    protected void doStart() {
        if (!enabled) {
            return;
        }
        scheduledFuture = threadPool.scheduleWithFixedDelay(new JvmMonitor(gcThresholds, gcOverheadThreshold) {
            @Override
            void onMonitorFailure(Exception e) {
                logger.debug("failed to monitor", e);
            }

            @Override
            void onSlowGc(final Threshold threshold, final long seq, final SlowGcEvent slowGcEvent) {
                logSlowGc(logger, threshold, seq, slowGcEvent, JvmGcMonitorService::buildPools);
            }

            @Override
            void onGcOverhead(final Threshold threshold, final long current, final long elapsed, final long seq) {
                logGcOverhead(logger, threshold, current, elapsed, seq);
            }
        }, interval, Names.SAME);
    }

     @Override
    protected void doStop() {
        if (!enabled) {
            return;
        }
        scheduledFuture.cancel();
    }

    @Override
    protected void doClose() {
    }

    //......
}

• JvmGcMonitorService的doStart方法通过scheduleWithFixedDelay注册了JvmMonitor的定时任务；其doStop方法则是cancel掉该定时任务

JvmMonitor

elasticsearch-7.0.1/server/src/main/java/org/elasticsearch/monitor/jvm/JvmGcMonitorService.java

abstract static class JvmMonitor implements Runnable {

        enum Threshold { DEBUG, INFO, WARN }

        static class SlowGcEvent {

            final GarbageCollector currentGc;
            final long collectionCount;
            final TimeValue collectionTime;
            final long elapsed;
            final JvmStats lastJvmStats;
            final JvmStats currentJvmStats;
            final ByteSizeValue maxHeapUsed;

            SlowGcEvent(
                final GarbageCollector currentGc,
                final long collectionCount,
                final TimeValue collectionTime,
                final long elapsed,
                final JvmStats lastJvmStats,
                final JvmStats currentJvmStats,
                final ByteSizeValue maxHeapUsed) {
                this.currentGc = currentGc;
                this.collectionCount = collectionCount;
                this.collectionTime = collectionTime;
                this.elapsed = elapsed;
                this.lastJvmStats = lastJvmStats;
                this.currentJvmStats = currentJvmStats;
                this.maxHeapUsed = maxHeapUsed;
            }

        }

        private long lastTime = now();
        private JvmStats lastJvmStats = jvmStats();
        private long seq = 0;
        private final Map<String, JvmGcMonitorService.GcThreshold> gcThresholds;
        final GcOverheadThreshold gcOverheadThreshold;

        JvmMonitor(final Map<String, GcThreshold> gcThresholds, final GcOverheadThreshold gcOverheadThreshold) {
            this.gcThresholds = Objects.requireNonNull(gcThresholds);
            this.gcOverheadThreshold = Objects.requireNonNull(gcOverheadThreshold);
        }

        @Override
        public void run() {
            try {
                monitorGc();
            } catch (Exception e) {
                onMonitorFailure(e);
            }
        }

        abstract void onMonitorFailure(Exception e);

        synchronized void monitorGc() {
            seq++;
            final long currentTime = now();
            JvmStats currentJvmStats = jvmStats();

            final long elapsed = TimeUnit.NANOSECONDS.toMillis(currentTime - lastTime);

            monitorSlowGc(currentJvmStats, elapsed);
            monitorGcOverhead(currentJvmStats, elapsed);

            lastTime = currentTime;
            lastJvmStats = currentJvmStats;
        }

        final void monitorSlowGc(JvmStats currentJvmStats, long elapsed) {
            for (int i = 0; i < currentJvmStats.getGc().getCollectors().length; i++) {
                GarbageCollector gc = currentJvmStats.getGc().getCollectors()[i];
                GarbageCollector prevGc = lastJvmStats.getGc().getCollectors()[i];

                // no collection has happened
                long collections = gc.getCollectionCount() - prevGc.getCollectionCount();
                if (collections == 0) {
                    continue;
                }
                long collectionTime = gc.getCollectionTime().millis() - prevGc.getCollectionTime().millis();
                if (collectionTime == 0) {
                    continue;
                }

                GcThreshold gcThreshold = gcThresholds.get(gc.getName());
                if (gcThreshold == null) {
                    gcThreshold = gcThresholds.get("default");
                }

                long avgCollectionTime = collectionTime / collections;

                Threshold threshold = null;
                if (avgCollectionTime > gcThreshold.warnThreshold) {
                    threshold = Threshold.WARN;
                } else if (avgCollectionTime > gcThreshold.infoThreshold) {
                    threshold = Threshold.INFO;
                } else if (avgCollectionTime > gcThreshold.debugThreshold) {
                    threshold = Threshold.DEBUG;
                }
                if (threshold != null) {
                    onSlowGc(threshold, seq, new SlowGcEvent(
                        gc,
                        collections,
                        TimeValue.timeValueMillis(collectionTime),
                        elapsed,
                        lastJvmStats,
                        currentJvmStats,
                        JvmInfo.jvmInfo().getMem().getHeapMax()));
                }
            }
        }

        final void monitorGcOverhead(final JvmStats currentJvmStats, final long elapsed) {
            long current = 0;
            for (int i = 0; i < currentJvmStats.getGc().getCollectors().length; i++) {
                GarbageCollector gc = currentJvmStats.getGc().getCollectors()[i];
                GarbageCollector prevGc = lastJvmStats.getGc().getCollectors()[i];
                current += gc.getCollectionTime().millis() - prevGc.getCollectionTime().millis();
            }
            checkGcOverhead(current, elapsed, seq);
        }

        void checkGcOverhead(final long current, final long elapsed, final long seq) {
            final int fraction = (int) ((100 * current) / (double) elapsed);
            Threshold overheadThreshold = null;
            if (fraction >= gcOverheadThreshold.warnThreshold) {
                overheadThreshold = Threshold.WARN;
            } else if (fraction >= gcOverheadThreshold.infoThreshold) {
                overheadThreshold = Threshold.INFO;
            } else if (fraction >= gcOverheadThreshold.debugThreshold) {
                overheadThreshold = Threshold.DEBUG;
            }
            if (overheadThreshold != null) {
                onGcOverhead(overheadThreshold, current, elapsed, seq);
            }
        }

        JvmStats jvmStats() {
            return JvmStats.jvmStats();
        }

        long now() {
            return System.nanoTime();
        }

        abstract void onSlowGc(Threshold threshold, long seq, SlowGcEvent slowGcEvent);

        abstract void onGcOverhead(Threshold threshold, long total, long elapsed, long seq);

    }

• JvmMonitor实现了Runnable接口，其run方法执行monitorGc方法，异常时执行onMonitorFailure方法；JvmMonitor还定义了onMonitorFailure、onSlowGc、onGcOverhead抽象方法需要子类去实现
• monitorGc方法首先获取currentJvmStats，然后执行monitorSlowGc及monitorGcOverhead
• monitorSlowGc方法主要是计算avgCollectionTime，然后判断是否超出指定level的阈值，超出则回调onSlowGc方法；monitorGcOverhead方法主要是计算gc耗时占比，如果判断是否超过指定level的阈值，超出则回调onGcOverhead方法

小结

• MonitorService的构造器创建了jvmGcMonitorService、osService、processService、jvmService、fsService；其doStart、doStop、doClose分别调用了jvmGcMonitorService的start、stop、close方法
• JvmGcMonitorService的doStart方法通过scheduleWithFixedDelay注册了JvmMonitor的定时任务；其doStop方法则是cancel掉该定时任务
• JvmMonitor实现了Runnable接口，其run方法执行monitorGc方法，异常时执行onMonitorFailure方法；JvmMonitor还定义了onMonitorFailure、onSlowGc、onGcOverhead抽象方法需要子类去实现

doc

• MonitorService