KKcorps commented on code in PR #15261: URL: https://github.com/apache/pinot/pull/15261#discussion_r2009517952
########## pinot-core/src/main/java/org/apache/pinot/core/data/manager/realtime/SemaphoreAccessCoordinator.java: ########## @@ -0,0 +1,241 @@ +/** + * 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.base.Preconditions; +import java.util.Map; +import java.util.concurrent.Semaphore; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.concurrent.locks.Condition; +import java.util.concurrent.locks.Lock; +import java.util.concurrent.locks.ReentrantLock; +import javax.annotation.Nullable; +import org.apache.pinot.common.metadata.segment.SegmentZKMetadata; +import org.apache.pinot.common.utils.LLCSegmentName; +import org.apache.pinot.common.utils.helix.HelixHelper; +import org.apache.pinot.segment.local.data.manager.SegmentDataManager; +import org.apache.pinot.spi.config.table.ingestion.StreamIngestionConfig; +import org.apache.pinot.spi.utils.CommonConstants; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + + +public class SemaphoreAccessCoordinator { + + private static final Logger LOGGER = LoggerFactory.getLogger(SemaphoreAccessCoordinator.class); + + private final Semaphore _semaphore; + private final boolean _enforceConsumptionInOrder; + private final Condition _condition; + private final Lock _lock; + private int _maxSegmentSeqNumLoaded = -1; + private boolean _relyOnIdealState = false; + private final RealtimeTableDataManager _realtimeTableDataManager; + private final AtomicBoolean _isFirstTransitionProcessed; + + public SemaphoreAccessCoordinator(Semaphore semaphore, boolean enforceConsumptionInOrder, + RealtimeTableDataManager realtimeTableDataManager) { + _semaphore = semaphore; + _lock = new ReentrantLock(); + _condition = _lock.newCondition(); + _enforceConsumptionInOrder = enforceConsumptionInOrder; + _realtimeTableDataManager = realtimeTableDataManager; + StreamIngestionConfig streamIngestionConfig = realtimeTableDataManager.getStreamIngestionConfig(); + boolean trackSegmentSeqNumber = false; + if (streamIngestionConfig != null) { + trackSegmentSeqNumber = streamIngestionConfig.isTrackSegmentSeqNumber(); + } + // if trackSegmentSeqNumber is false, server relies on ideal state to fetch previous segment to a segment. + if (!trackSegmentSeqNumber) { + _relyOnIdealState = true; + } + _isFirstTransitionProcessed = new AtomicBoolean(false); + } + + public void acquire(LLCSegmentName llcSegmentName) + throws InterruptedException { + + String segmentName = llcSegmentName.getSegmentName(); + + if (_enforceConsumptionInOrder) { + waitForPrevSegment(llcSegmentName); + } + + long startTimeMs = System.currentTimeMillis(); + while (!_semaphore.tryAcquire(5, TimeUnit.MINUTES)) { + LOGGER.warn("Failed to acquire partitionGroup consumer semaphore in: {} ms. Retrying.", + System.currentTimeMillis() - startTimeMs); + + // if segment is marked online/offline by any instance, just return the current offline -> consuming + // transition. + if (!_enforceConsumptionInOrder && !isSegmentInProgress(segmentName)) { + throw new SegmentAlreadyConsumedException("segment: " + segmentName + " status must be in progress"); + } + } + } + + public void release() { + _semaphore.release(); + } + + public Semaphore getSemaphore() { + return _semaphore; + } + + public void trackSegment(LLCSegmentName llcSegmentName) { + _lock.lock(); + try { + if (!_relyOnIdealState) { + _maxSegmentSeqNumLoaded = Math.max(_maxSegmentSeqNumLoaded, llcSegmentName.getSequenceNumber()); + } + // notify all helix threads waiting for their offline -> consuming segment's prev segment to be loaded + _condition.signalAll(); + } finally { + _lock.unlock(); + } + } + + private void waitForPrevSegment(LLCSegmentName currSegment) + throws InterruptedException { + + long startTimeMs = System.currentTimeMillis(); + + if ((_relyOnIdealState) || (!_isFirstTransitionProcessed.get())) { + // if _relyOnIdealState or no offline -> consuming transition has been processed, it means rely on + // ideal state to fetch previous segment. + String previousSegment = getPreviousSegment(currSegment); Review Comment: Instead of waiting on previous segment, I feel we can simply let the previous segment signal which transition to start next this is because the coordinator has complete view of what all transitions are waiting and can take correct decision it doesn't need to care about missing segments and all ########## pinot-core/src/main/java/org/apache/pinot/core/data/manager/realtime/SemaphoreAccessCoordinator.java: ########## @@ -0,0 +1,251 @@ +/** + * 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.base.Preconditions; +import java.util.HashSet; +import java.util.Map; +import java.util.Set; +import java.util.concurrent.Semaphore; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.concurrent.locks.Condition; +import java.util.concurrent.locks.Lock; +import java.util.concurrent.locks.ReentrantLock; +import javax.annotation.Nullable; +import org.apache.pinot.common.metadata.segment.SegmentZKMetadata; +import org.apache.pinot.common.utils.LLCSegmentName; +import org.apache.pinot.common.utils.helix.HelixHelper; +import org.apache.pinot.segment.local.data.manager.SegmentDataManager; +import org.apache.pinot.spi.config.table.ingestion.StreamIngestionConfig; +import org.apache.pinot.spi.utils.CommonConstants; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + + +public class SemaphoreAccessCoordinator { + + private static final Logger LOGGER = LoggerFactory.getLogger(SemaphoreAccessCoordinator.class); + + private final Semaphore _semaphore; + private final boolean _enforceConsumptionInOrder; + private final Condition _condition; + private final Lock _lock; + @Nullable + private Set<Integer> _segmentSequenceNumSet = null; + private final RealtimeTableDataManager _realtimeTableDataManager; + private final AtomicBoolean _isFirstTransitionProcessed; + + public SemaphoreAccessCoordinator(Semaphore semaphore, boolean enforceConsumptionInOrder, + RealtimeTableDataManager realtimeTableDataManager) { + _semaphore = semaphore; + _lock = new ReentrantLock(); + _condition = _lock.newCondition(); + _enforceConsumptionInOrder = enforceConsumptionInOrder; + _realtimeTableDataManager = realtimeTableDataManager; + StreamIngestionConfig streamIngestionConfig = realtimeTableDataManager.getStreamIngestionConfig(); + boolean trackSegmentSeqNumber = false; + if (streamIngestionConfig != null) { + trackSegmentSeqNumber = streamIngestionConfig.isTrackSegmentSeqNumber(); + } + // if trackSegmentSeqNumber is false, server relies on ideal state to fetch previous segment to a segment. + if (trackSegmentSeqNumber) { + _segmentSequenceNumSet = new HashSet<>(); + } + _isFirstTransitionProcessed = new AtomicBoolean(false); + } + + public void acquire(LLCSegmentName llcSegmentName) + throws InterruptedException { + + String segmentName = llcSegmentName.getSegmentName(); + + if (_enforceConsumptionInOrder) { + waitForPrevSegment(llcSegmentName); + } + + long startTimeMs = System.currentTimeMillis(); + while (!_semaphore.tryAcquire(5, TimeUnit.MINUTES)) { + LOGGER.warn("Failed to acquire partitionGroup consumer semaphore in: {} ms. Retrying.", + System.currentTimeMillis() - startTimeMs); + + // if segment is marked online/offline by any instance, just return the current offline -> consuming + // transition. + if (!_enforceConsumptionInOrder && !isSegmentInProgress(segmentName)) { + throw new SegmentAlreadyConsumedException("segment: " + segmentName + " status must be in progress"); + } + } + } + + public void release() { + _semaphore.release(); + } + + public Semaphore getSemaphore() { + return _semaphore; + } + + public void trackSegment(LLCSegmentName llcSegmentName) { + _lock.lock(); + try { + if (_segmentSequenceNumSet != null) { + _segmentSequenceNumSet.add(llcSegmentName.getSequenceNumber()); + } + // notify all helix threads waiting for their offline -> consuming segment's prev segment to be loaded + _condition.signalAll(); + } finally { + _lock.unlock(); + } + } + + private void waitUntilTableIsReady() + throws InterruptedException { + while (!_realtimeTableDataManager.getIsTableReadyToConsumeData().getAsBoolean()) { + Thread.sleep(RealtimeTableDataManager.READY_TO_CONSUME_DATA_CHECK_INTERVAL_MS); + } + } + + private void waitForPrevSegment(LLCSegmentName currSegment) + throws InterruptedException { + + long startTimeMs = System.currentTimeMillis(); + + if ((_segmentSequenceNumSet == null) || (!_isFirstTransitionProcessed.get())) { + // if _segmentSequenceNumSet is null or no offline -> consuming transition has been processed, it means rely on + // ideal state to fetch previous segment. + String previousSegment = getPreviousSegment(currSegment); + if (previousSegment == null) { + // previous segment can only be null if either all the previous segments are deleted or this is the starting + // sequence segment of the partition Group. + return; + } + + SegmentDataManager segmentDataManager = _realtimeTableDataManager.acquireSegment(previousSegment); + try { + _lock.lock(); + while (segmentDataManager == null) { + // if segmentDataManager == null, it means segment is not loaded in the server. + // wait until it's loaded. + while (!_condition.await(5, TimeUnit.MINUTES)) { + LOGGER.warn("Semaphore access denied to segment: {}. Waiting on previous segment: {} since: {} ms.", + currSegment.getSegmentName(), previousSegment, System.currentTimeMillis() - startTimeMs); + } + segmentDataManager = _realtimeTableDataManager.acquireSegment(previousSegment); + } + } finally { + _lock.unlock(); + if (segmentDataManager != null) { + _realtimeTableDataManager.releaseSegment(segmentDataManager); + } + } + + // the first transition will always be prone to error, consider edge case where segment previous to current + // helix transition's segment was deleted and this server came alive after successful deletion. the prev + // segment will not exist, hence first transition is handled using isFirstTransitionSuccessful. + _isFirstTransitionProcessed.compareAndSet(false, true); + return; + } + + int prevSeqNum = currSegment.getSequenceNumber() - 1; + _lock.lock(); + try { + while (!_segmentSequenceNumSet.contains(prevSeqNum)) { + // if _segmentSequenceNumSet does not contain prev segment's seq num, it means segment is not loaded in the + // server. Wait until it's loaded. + while (!_condition.await(5, TimeUnit.MINUTES)) { + LOGGER.warn("Semaphore access denied to segment: {}." + + " Waiting on previous segment with sequence number: {} since: {} ms.", currSegment.getSegmentName(), + prevSeqNum, System.currentTimeMillis() - startTimeMs); + } + } + } finally { + _lock.unlock(); + } + } + + @Nullable + private String getPreviousSegment(LLCSegmentName currSegment) { + // if seq num of current segment is 102, maxSequenceNumBelowCurrentSegment must be highest seq num of any segment + // created before current segment + int maxSequenceNumBelowCurrentSegment = -1; + String previousSegment = null; + int currPartitionGroupId = currSegment.getPartitionGroupId(); + int currSequenceNum = currSegment.getSequenceNumber(); + + Map<String, Map<String, String>> segmentAssignment = + HelixHelper.getSegmentAssignment(_realtimeTableDataManager.getTableName(), Review Comment: Instead of waiting on previous segment, I feel we can simply let the previous segment signal which transition to start next this is because the coordinator has complete view of what all transitions are waiting and can take correct decision it doesn't need to care about missing segments and all -- This is an automated message from the Apache Git Service. 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