Vivek1106-04 commented on code in PR #12165: URL: https://github.com/apache/seatunnel/pull/12165#discussion_r4071767608
########## seatunnel-engine/seatunnel-engine-server/src/main/java/org/apache/seatunnel/engine/server/checkpoint/scheduler/SharedCheckpointScheduler.java: ########## @@ -0,0 +1,141 @@ +/* + * 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.seatunnel.engine.server.checkpoint.scheduler; + +import org.apache.seatunnel.shade.com.google.common.util.concurrent.ThreadFactoryBuilder; + +import lombok.extern.slf4j.Slf4j; + +import java.util.concurrent.ExecutorService; +import java.util.concurrent.Executors; +import java.util.concurrent.RejectedExecutionException; +import java.util.concurrent.ScheduledFuture; +import java.util.concurrent.ScheduledThreadPoolExecutor; +import java.util.concurrent.TimeUnit; + +/** + * Node-wide scheduler shared by every checkpoint coordinator on this member. + * + * <p>Before this existed, each {@code CheckpointCoordinator} built its own two-thread scheduled + * pool, so timer threads grew with the number of active pipelines. The coordinators only ever used + * that pool as a timer: to re-arm the periodic checkpoint trigger and to arm the checkpoint-timeout + * watchdog. This class keeps a single small timer pool for the whole member and hands each + * coordinator a {@link PipelineCheckpointScheduler} lease. + * + * <p>Timing and execution are deliberately split across two pools. A timer thread does nothing but + * hand the task to the dispatch pool, so a checkpoint body that blocks on an RPC delays neither its + * own pipeline's next timer nor any other pipeline's. The dispatch pool is elastic and reaps idle + * threads, so it is not a fixed cost per pipeline either. + * + * <p>Checkpoint work is intentionally not dispatched onto the coordinator executor: that pool is + * bounded over a {@code SynchronousQueue} and rejects work when saturated, which would silently + * drop a checkpoint trigger or a timeout watchdog. + * + * <p>One instance is held per member by {@code SeaTunnelEngineContext}. It is not a singleton + * because several members run in one JVM during tests and E2E runs. + */ +@Slf4j +public class SharedCheckpointScheduler implements AutoCloseable { + + /** + * Timer threads only dispatch, so a small fixed pool is enough regardless of pipeline count. + * Two threads keep one slow dispatch hand-off from stalling the other timers. + */ + private static final int TIMER_THREAD_NUM = 2; + + private final ScheduledThreadPoolExecutor timer; + private final ExecutorService dispatcher; + private volatile boolean closed = false; + + public SharedCheckpointScheduler() { + this.timer = + new ScheduledThreadPoolExecutor( + TIMER_THREAD_NUM, + new ThreadFactoryBuilder() + .setNameFormat("checkpoint-timer-%d") + .setDaemon(true) + .build()); + // Coordinators cancel the timeout watchdog on every acknowledged checkpoint. Without this, + // cancelled entries would sit in the shared queue until their delay elapsed. + this.timer.setRemoveOnCancelPolicy(true); + this.dispatcher = + Executors.newCachedThreadPool( + new ThreadFactoryBuilder() + .setNameFormat("checkpoint-dispatcher-%d") + .setDaemon(true) + .build()); + } + + /** + * Creates a timer lease for one pipeline. + * + * <p>The lease is the cancellation unit: it is identified by {@code (jobId, pipelineId)} and + * holds only its own outstanding tasks. Nothing is registered on this object, so dropping a + * lease when its job ends leaks nothing. + * + * @param jobId the owning job + * @param pipelineId the owning pipeline + * @return a lease that borrows this member's shared timer and dispatch threads + */ + public PipelineCheckpointScheduler lease(long jobId, int pipelineId) { + return new PipelineCheckpointScheduler(this, jobId, pipelineId); + } + + /** + * Arms {@code task} on the shared timer so that it is handed to the dispatch pool after {@code + * delay}. + * + * @return the timer-side future, or {@code null} if this scheduler is already shutting down + */ + ScheduledFuture<?> dispatchAfter(PipelineCheckpointTask task, long delay, TimeUnit unit) { + try { + return timer.schedule(() -> submit(task), delay, unit); + } catch (RejectedExecutionException e) { + // Only reachable once close() has begun; the coordinator is stopping anyway. + log.debug("Shared checkpoint scheduler is shut down, dropping timer task", e); + task.cancel(false); + return null; + } + } + + private void submit(PipelineCheckpointTask task) { + try { + dispatcher.execute(task); + } catch (RejectedExecutionException e) { + log.debug("Shared checkpoint dispatcher is shut down, dropping checkpoint task", e); Review Comment: Filed as #12442, as promised above - an unexpected throw in `tryTriggerPendingCheckpoint` leaving a pipeline with no armed timer, logged nowhere through SeaTunnel's own logger. Pre-existing on `dev` and not made worse by this PR, so it is tracked rather than fixed here. -- 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]
