jugomezv commented on code in PR #9994: URL: https://github.com/apache/pinot/pull/9994#discussion_r1061991555
########## pinot-core/src/main/java/org/apache/pinot/core/data/manager/realtime/IngestionDelayTracker.java: ########## @@ -0,0 +1,350 @@ +/** + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ + +package org.apache.pinot.core.data.manager.realtime; + +import com.google.common.annotations.VisibleForTesting; +import java.util.HashSet; +import java.util.List; +import java.util.Timer; +import java.util.TimerTask; +import java.util.concurrent.ConcurrentHashMap; +import org.apache.pinot.common.metrics.ServerGauge; +import org.apache.pinot.common.metrics.ServerMetrics; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + + +/** + * A Class to track realtime ingestion delay for a given table on a given server. + * Highlights: + * 1-An object of this class is hosted by each RealtimeTableDataManager. + * 2-The object tracks ingestion delays for all partitions hosted by the current server for the given Realtime table. + * 3-Partition delays are updated by all LLRealtimeSegmentDataManager objects hosted in the corresponding + * RealtimeTableDataManager. + * 4-The class tracks the maximum of all ingestion delays observed for all partitions of the given table. + * 5-A Metric is derived from reading the maximum tracked by this class. And individual metrics are associated with + * each partition being tracked. + * 6-Delays reported for partitions that do not have events to consume are reported as zero. + * 7-We track the time at which each delay sample was collected so that delay can be increased when partition stops + * consuming for any reason other than no events being available for consumption. + * 8-Segments that go from CONSUMING to DROPPED states stop being tracked so their delays do not cloud + * delays of active partitions. + * 9-When a segment goes from CONSUMING to ONLINE, we start a timeout for the corresponding partition. + * If no consumption is noticed after the timeout, we then read ideal state to confirm the server still hosts the + * partition. If not, we stop tracking the respective partition. + * 10-A timer thread is started by this object to track timeouts of partitions and drive the reading of their ideal + * state. + * + * The following diagram illustrates the object interactions with main external APIs + * + * (CONSUMING -> ONLINE state change) + * | + * markPartitionForConfirmation(partitionId) + * | |<-updateIngestionDelay()-{LLRealtimeSegmentDataManager(Partition 0}} + * | | + * ___________V_________________________V_ + * | (Table X) |<-updateIngestionDelay()-{LLRealtimeSegmentDataManager(Partition 1}} + * | IngestionDelayTracker | ... + * |____________________________________|<-updateIngestionDelay()-{LLRealtimeSegmentDataManager (Partition n}} + * ^ ^ + * | \ + * timeoutInactivePartitions() stopTrackingPartitionIngestionDelay(partitionId) + * _________|__________ \ + * | TimerTrackingTask | (CONSUMING -> DROPPED state change) + * |___________________| + * + */ + +public class IngestionDelayTracker { + + // Sleep interval for timer thread that triggers read of ideal state + private static final int TIMER_THREAD_TICK_INTERVAL_MS = 300000; // 5 minutes +/- precision in timeouts + // Once a partition is marked for verification, we wait 10 minutes to pull its ideal state. + private static final int PARTITION_TIMEOUT_MS = 600000; // 10 minutes timeouts + // Delay Timer thread for this time after starting timer + private static final int INITIAL_TIMER_THREAD_DELAY_MS = 100; + + /* + * Class to keep an ingestion delay measure and the time when the sample was taken (i.e. sample time) + * We will use the sample time to increase ingestion delay when a partition stops consuming: the time + * difference between the sample time and current time will be added to the metric when read. + */ + static private class DelayMeasure { + public DelayMeasure(long t, long d) { + _delayMilliseconds = d; + _sampleTime = t; + } + public final long _delayMilliseconds; + public final long _sampleTime; + } + + // HashMap used to store delay measures for all partitions active for the current table. + // _partitionsToDelaySampleMap<Key=PartitionGroupId,Value=DelaySample> + private ConcurrentHashMap<Integer, DelayMeasure> _partitionToDelaySampleMap = new ConcurrentHashMap<>(); + // We mark partitions that go from CONSUMING to ONLINE in _partitionsMarkedForVerification: if they do not + // go back to CONSUMING in some period of time, we confirm whether they are still hosted in this server by reading + // ideal state. This is done with the goal of minimizing reading ideal state for efficiency reasons. + // _partitionsMarkedForVerification<Key=PartitionGroupId,Value=TimePartitionWasMarkedForVerificationMilliseconds> + private ConcurrentHashMap<Integer, Long> _partitionsMarkedForVerification = new ConcurrentHashMap<>(); + // Mutable versions of timer constants so we can test with smaller delays + final int _timerThreadTickIntervalMs; + // Timer task to check partitions that are inactive against ideal state. + private final Timer _timer; + + private final ServerMetrics _serverMetrics; + private final String _tableNameWithType; + + private boolean _enableAging; + private final boolean _enablePerPartitionMetric; + private final boolean _enableAggregateMetric; + private final Logger _logger; + + private final RealtimeTableDataManager _realTimeTableDataManager; + + /* + * Helper function to update the maximum when the current maximum is removed or updated. + * If no samples left we set maximum to minimum so new samples can be recorded. + */ + private DelayMeasure getMaximumDelay() { + DelayMeasure newMax = null; + for (int partitionGroupId : _partitionToDelaySampleMap.keySet()) { + DelayMeasure currentMeasure = _partitionToDelaySampleMap.get(partitionGroupId); + if ((newMax == null) + || + (currentMeasure != null) && (currentMeasure._delayMilliseconds > newMax._delayMilliseconds)) { + newMax = currentMeasure; + } + } + return newMax; + } + + /* + * Helper function to age a delay measure. Aging means adding the time elapsed since the measure was + * taken till the measure is being reported. + */ + private long getAgedDelay(DelayMeasure currentDelay) { + if (currentDelay == null) { + return 0; // return 0 when not initialized + } + // Add age of measure to the reported value + long measureAgeInMs = _enableAging ? (System.currentTimeMillis() - currentDelay._sampleTime) : 0; + // Correct to zero for any time shifts due to NTP or time reset. + measureAgeInMs = Math.max(measureAgeInMs, 0); + return currentDelay._delayMilliseconds + measureAgeInMs; + } + + private List<Integer> getPartitionsHostedByThisServerPerIdealState() { + return _realTimeTableDataManager.getHostedPartitionsGroupIds(); + } + /* + * Helper function to be called when we should stop tracking a given partition. Removes the partition from + * all our maps, it also updates the maximum if the tracked partition was the previous maximum. + * + * @param partitionGroupId partition ID which we should stop tracking. + */ + private void removePartitionId(int partitionGroupId) { + _partitionToDelaySampleMap.remove(partitionGroupId); + // If we are removing a partition we should stop reading its ideal state. + _partitionsMarkedForVerification.remove(partitionGroupId); + if (_enablePerPartitionMetric) { + _serverMetrics.removeTableGauge(getPerPartitionMetricName(partitionGroupId), + ServerGauge.TABLE_PER_PARTITION_INGESTION_DELAY_MS); + } + } + + /* + * Helper function to generate a per partition metric name. + * + * @param partitionGroupId the partition group id to be appended to the table name so we + * can differentiate between metrics for various partitions. + * + * @return a metric name with the following structure: tableNameWithType + partitionGroupId + */ + private String getPerPartitionMetricName(int partitionGroupId) { + return _tableNameWithType + partitionGroupId; + } + + // Custom Constructor + public IngestionDelayTracker(ServerMetrics serverMetrics, String tableNameWithType, + RealtimeTableDataManager realtimeTableDataManager, int timerThreadTickIntervalMs, String metricNamePrefix, + boolean enableAggregateMetric, boolean enablePerPartitionMetric) + throws RuntimeException { + _logger = LoggerFactory.getLogger(tableNameWithType + "-" + getClass().getSimpleName()); + _serverMetrics = serverMetrics; + _tableNameWithType = metricNamePrefix + tableNameWithType; + _realTimeTableDataManager = realtimeTableDataManager; + // Handle negative timer values + if (timerThreadTickIntervalMs <= 0) { + throw new RuntimeException("Illegal timer timeout argument, expected > 0, got=" + timerThreadTickIntervalMs); + } + _enableAging = true; + _enablePerPartitionMetric = enablePerPartitionMetric; + _enableAggregateMetric = enableAggregateMetric; + _timerThreadTickIntervalMs = timerThreadTickIntervalMs; + _timer = new Timer("IngestionDelayTimerThread" + tableNameWithType); + _timer.schedule(new TimerTask() { + @Override + public void run() { + timeoutInactivePartitions(); + } + }, INITIAL_TIMER_THREAD_DELAY_MS, _timerThreadTickIntervalMs); + // Install callback metric + if (_enableAggregateMetric) { + _serverMetrics.addCallbackTableGaugeIfNeeded(_tableNameWithType, ServerGauge.TABLE_MAX_INGESTION_DELAY_MS, + () -> getMaximumIngestionDelay()); + } + } + + // Constructor that uses defaults + public IngestionDelayTracker(ServerMetrics serverMetrics, String tableNameWithType, + RealtimeTableDataManager tableDataManager) { + this(serverMetrics, tableNameWithType, tableDataManager, TIMER_THREAD_TICK_INTERVAL_MS, + "", true, true); + } + + // Constructor that takes a prefix to name the metric, so we can keep multiple trackers for the same table + public IngestionDelayTracker(ServerMetrics serverMetrics, String tableNameWithType, String metricNamePrefix, + RealtimeTableDataManager tableDataManager) { + this(serverMetrics, metricNamePrefix + tableNameWithType, tableDataManager, + TIMER_THREAD_TICK_INTERVAL_MS, metricNamePrefix, true, true); + } + + + /** + * Use to set or reset the aging of reported values. + * @param enableAging true if we want maximum to be aged as per sample time or false if we do not want to age + * samples + */ + @VisibleForTesting + void setEnableAging(boolean enableAging) { + _enableAging = enableAging; + } + + /* + * Called by LLRealTimeSegmentDataManagers to post delay updates to this tracker class. + * If the new sample represents a new Maximum we update the current maximum. + * If the new sample was for the partition that was maximum, but delay is not maximum anymore, we must select + * a new maximum. + * + * @param delayInMilliseconds ingestion delay being recorded. + * @param sampleTime sample time. + * @param partitionGroupId partition ID for which this delay is being recorded. + */ + public void updateIngestionDelay(long delayInMilliseconds, long sampleTime, int partitionGroupId) { + // Store new measure and wipe old one for this partition + DelayMeasure previousMeasure = _partitionToDelaySampleMap.put(partitionGroupId, + new DelayMeasure(sampleTime, delayInMilliseconds)); + if ((previousMeasure == null) && _enablePerPartitionMetric) { + // First time we start tracking a partition we should start tracking it via metric + _serverMetrics.addCallbackTableGaugeIfNeeded(getPerPartitionMetricName(partitionGroupId), + ServerGauge.TABLE_PER_PARTITION_INGESTION_DELAY_MS, + () -> getPartitionIngestionDelay(partitionGroupId)); + } + // If we are consuming we do not need to track this partition for removal. + _partitionsMarkedForVerification.remove(partitionGroupId); + } + + /* + * Handle partition removal event. This must be invoked when we stop serving a given partition for + * this table in the current server. + * This function will be invoked when we receive CONSUMING -> DROPPED / OFFLINE state transitions. + * + * @param partitionGroupId partition id that we should stop tracking. + */ + public void stopTrackingPartitionIngestionDelay(int partitionGroupId) { + removePartitionId(partitionGroupId); + } + + /* + * This method is used for timing out inactive partitions, so we don't display their metrics on current server. + * When the inactive time exceeds some threshold, we read from ideal state to confirm we still host the partition, + * if not we remove the partition from being tracked locally. + * This call is to be invoked by a timer thread that will periodically wake up and invoke this function. + */ + public void timeoutInactivePartitions() { + List<Integer> partitionsHostedByThisServer = null; + try { + partitionsHostedByThisServer = getPartitionsHostedByThisServerPerIdealState(); Review Comment: Done in the las commit -- This is an automated message from the Apache Git Service. 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