AmandeepSingh285 commented on code in PR #3810: URL: https://github.com/apache/celeborn/pull/3810#discussion_r3836124195
########## master/src/main/java/org/apache/celeborn/service/deploy/master/clustermeta/ha/HeartbeatAggregator.java: ########## @@ -0,0 +1,152 @@ +/* + * 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.celeborn.service.deploy.master.clustermeta.ha; + +import java.util.ArrayList; +import java.util.HashMap; +import java.util.List; +import java.util.Map; +import java.util.concurrent.ScheduledExecutorService; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.locks.ReentrantLock; + +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import org.apache.celeborn.common.CelebornConf; +import org.apache.celeborn.common.client.MasterClient; +import org.apache.celeborn.common.util.ThreadUtils; +import org.apache.celeborn.service.deploy.master.clustermeta.ResourceProtos; +import org.apache.celeborn.service.deploy.master.clustermeta.ResourceProtos.ResourceRequest; +import org.apache.celeborn.service.deploy.master.clustermeta.ResourceProtos.Type; + +public class HeartbeatAggregator { + private static final Logger LOG = LoggerFactory.getLogger(HeartbeatAggregator.class); + + private final HARaftServer ratisServer; + private final long batchIntervalMs; + + private final ReentrantLock pendingLock = new ReentrantLock(); + private Map<String, ResourceProtos.WorkerHeartbeatRequest> workerHeartbeats = new HashMap<>(); + private Map<String, ResourceProtos.AppHeartbeatRequest> appHeartbeats = new HashMap<>(); + + private final ScheduledExecutorService flushExecutor; + + public HeartbeatAggregator(HARaftServer ratisServer, CelebornConf conf) { + this.ratisServer = ratisServer; + this.batchIntervalMs = conf.masterHaHeartbeatBatchIntervalMs(); + this.flushExecutor = + ThreadUtils.newDaemonSingleThreadScheduledExecutor("master-heartbeat-aggregator"); + this.flushExecutor.scheduleWithFixedDelay( + this::flushSafely, batchIntervalMs, batchIntervalMs, TimeUnit.MILLISECONDS); + LOG.info("HeartbeatAggregator started, flush interval {} ms.", batchIntervalMs); + } + + public void offerWorkerHeartbeat(ResourceProtos.WorkerHeartbeatRequest heartbeat) { + pendingLock.lock(); + try { + workerHeartbeats.put(workerKey(heartbeat), heartbeat); + } finally { + pendingLock.unlock(); + } + } + + public void offerAppHeartbeat(ResourceProtos.AppHeartbeatRequest heartbeat) { + pendingLock.lock(); + try { + appHeartbeats.put(heartbeat.getAppId(), heartbeat); + } finally { + pendingLock.unlock(); + } + } + + private static String workerKey(ResourceProtos.WorkerHeartbeatRequest heartbeat) { + return heartbeat.getHost() + + ":" + + heartbeat.getRpcPort() + + ":" + + heartbeat.getPushPort() + + ":" + + heartbeat.getFetchPort() + + ":" + + heartbeat.getReplicatePort(); + } + + public void stop() { + flushExecutor.shutdownNow(); + } + + private void flushSafely() { + try { + flush(); + } catch (Throwable t) { + // Dropped batches self-heal next interval. + LOG.error("Failed to flush aggregated heartbeats, dropping this batch.", t); + } + } + + private void flush() { + List<ResourceProtos.WorkerHeartbeatRequest> drainedWorkers; + List<ResourceProtos.AppHeartbeatRequest> drainedApps; + pendingLock.lock(); + try { + if (workerHeartbeats.isEmpty() && appHeartbeats.isEmpty()) { + return; + } + drainedWorkers = new ArrayList<>(workerHeartbeats.values()); + workerHeartbeats.clear(); + drainedApps = new ArrayList<>(appHeartbeats.values()); + appHeartbeats.clear(); + } finally { + pendingLock.unlock(); + } + + if (!ratisServer.isLeader()) { + return; + } + + ResourceRequest batchRequest = + ResourceRequest.newBuilder() + .setCmdType(Type.BatchHeartbeat) + .setRequestId(MasterClient.genRequestId()) + .setBatchHeartbeatRequest( + ResourceProtos.BatchHeartbeatRequest.newBuilder() + .addAllWorkerHeartbeats(drainedWorkers) Review Comment: If the active leader dies before the batched worker heartbeat is committed to Ratis, the new leader keeps the last applied worker snapshot. Load-aware slot allocation then ranks disks from stale flush/fetch times, usable space, and active slots, so traffic can keep landing on workers that have since become hot or unhealthy. highWorkload is applied only when that heartbeat is applied. If the lost heartbeat was the one that marked the worker overloaded, the new leader will still treat it as available and offer new slots until the next heartbeat (~30s). The same gap exists for decommission: the worker may already be draining from an event it received, but the status it reported in the lost heartbeat never reaches the new leader. Until the next heartbeat applies, the master can still give applications slots on a worker that is leaving the cluster. The impact of losing a worker/app heartbeat after this change could be significantly higher, as losing the subsequent heartbeat would further extend the period during which the leader operates on stale worker state. -- This is an automated message from the Apache Git Service. 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