yew1eb commented on code in PR #3810: URL: https://github.com/apache/celeborn/pull/3810#discussion_r3854555698
########## master/src/main/java/org/apache/celeborn/service/deploy/master/clustermeta/ha/HeartbeatAggregator.java: ########## @@ -0,0 +1,153 @@ +/* + * 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() { + flushSafely(); + 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) + .addAllAppHeartbeats(drainedApps) + .build()) + .build(); + long startNs = System.nanoTime(); + ratisServer.submitRequest(batchRequest); Review Comment: You're right that `submitRequest()` is synchronous, so a blocked Ratis call would stall the single flush thread and delay subsequent flushes. But an upper bound on pending entries shouldn't be necessary: 1. **Entries don't accumulate while the thread is blocked**. The maps are keyed by worker/app id with newest-wins semantics, and `flush()` drains and clears them under the lock before `submitRequest` — so heartbeats arriving during a blocked submit just overwrite into fresh maps, bounded by #workers + #apps, the same order as the master's own metadata. 2. **This blocking is pre-existing, with a larger blast radius on the non-batch path**. There, every heartbeat synchronously calls the same `submitRequest` on an RPC handler thread — a slow Ratis can stall many RPC threads at once, one per in-flight heartbeat. Batching reduces this to a single dedicated flush thread, and collapses per-heartbeat raft submions into one per flush window. 3. **The impact stays small**: a delayed flush means at most a few extra seconds of stale heartbeat state — far below the 120s/300s timeouts, self-heals next window — and the existingn log already fires when a submit exceeds the flush interval, so the condition is visible. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
