noob-se7en commented on code in PR #15261: URL: https://github.com/apache/pinot/pull/15261#discussion_r2011954639
########## pinot-core/src/main/java/org/apache/pinot/core/data/manager/realtime/ConsumerCoordinator.java: ########## @@ -0,0 +1,234 @@ +/** + * 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 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.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 ConsumerCoordinator { + + private static final Logger LOGGER = LoggerFactory.getLogger(ConsumerCoordinator.class); + + private final Semaphore _semaphore; + private final boolean _enforceConsumptionInOrder; + private final Condition _condition; + private final Lock _lock; + private int _maxSegmentSeqNumLoaded = -1; + private boolean _relyOnIdealState = true; + private final RealtimeTableDataManager _realtimeTableDataManager; + private final AtomicBoolean _isFirstTransitionProcessed; + + public ConsumerCoordinator(boolean enforceConsumptionInOrder, RealtimeTableDataManager realtimeTableDataManager) { + _semaphore = new Semaphore(1); + _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 = false; + } + _isFirstTransitionProcessed = new AtomicBoolean(false); + } + + void acquire(LLCSegmentName llcSegmentName) + throws InterruptedException { + + 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); + } + } + + void release() { + _semaphore.release(); + } + + @VisibleForTesting + Semaphore getSemaphore() { + return _semaphore; + } + + 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); + 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 (_maxSegmentSeqNumLoaded < prevSeqNum) { + // it means all segments until _maxSegmentSeqNumLoaded 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(); + } + } + + @VisibleForTesting + @Nullable + String getPreviousSegment(LLCSegmentName currSegment) { Review Comment: > Currently we rely on the start-up check to ensure all segments loaded, so we can skip the first state transition check. Didn't completely get this. I think we need this. I am thinking for case where a slow server comes back online after being dead. While it was dead segment 101 was deleted. When it comes back online it's slow and multiple (offline->consuming) transitions are pending starting from segment 102. There is no guarantee that the first helix transition racing to acquire semaphore will be segment 102. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: commits-unsubscr...@pinot.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@pinot.apache.org For additional commands, e-mail: commits-h...@pinot.apache.org
