guozhangwang commented on code in PR #12128: URL: https://github.com/apache/kafka/pull/12128#discussion_r866368735
########## streams/src/main/java/org/apache/kafka/streams/processor/internals/DefaultStateUpdater.java: ########## @@ -0,0 +1,373 @@ +/* + * 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.kafka.streams.processor.internals; + +import org.apache.kafka.common.TopicPartition; +import org.apache.kafka.common.utils.LogContext; +import org.apache.kafka.common.utils.Time; +import org.apache.kafka.streams.errors.StreamsException; +import org.apache.kafka.streams.errors.TaskCorruptedException; +import org.apache.kafka.streams.processor.TaskId; +import org.apache.kafka.streams.processor.internals.Task.State; +import org.slf4j.Logger; + +import java.time.Duration; +import java.util.ArrayList; +import java.util.Collection; +import java.util.Collections; +import java.util.HashMap; +import java.util.HashSet; +import java.util.LinkedList; +import java.util.List; +import java.util.Map; +import java.util.Queue; +import java.util.Set; +import java.util.concurrent.BlockingQueue; +import java.util.concurrent.LinkedBlockingQueue; +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 java.util.stream.Collectors; + +public class DefaultStateUpdater implements StateUpdater { + + private final static String BUG_ERROR_MESSAGE = "This indicates a bug. " + + "Please report at https://issues.apache.org/jira/projects/KAFKA/issues or to the dev-mailing list (https://kafka.apache.org/contact)."; + + private class StateUpdaterThread extends Thread { + + private final ChangelogReader changelogReader; + private final AtomicBoolean isRunning = new AtomicBoolean(true); + private final java.util.function.Consumer<Set<TopicPartition>> offsetResetter; + private final Map<TaskId, Task> updatingTasks = new HashMap<>(); + private final Logger log; + + public StateUpdaterThread(final String name, + final ChangelogReader changelogReader, + final java.util.function.Consumer<Set<TopicPartition>> offsetResetter) { + super(name); + this.changelogReader = changelogReader; + this.offsetResetter = offsetResetter; + + final String logPrefix = String.format("%s ", name); + final LogContext logContext = new LogContext(logPrefix); + log = logContext.logger(DefaultStateUpdater.class); + } + + public Collection<Task> getAllUpdatingTasks() { + return updatingTasks.values(); + } + + @Override + public void run() { + try { + while (isRunning.get()) { + try { + performActionsOnTasks(); + restoreTasks(); + waitIfAllChangelogsCompletelyRead(); + } catch (final InterruptedException interruptedException) { + return; + } + } + } catch (final RuntimeException anyOtherException) { + log.error("An unexpected error occurred within the state updater thread: " + anyOtherException); + final ExceptionAndTasks exceptionAndTasks = new ExceptionAndTasks(new HashSet<>(updatingTasks.values()), anyOtherException); + updatingTasks.clear(); + failedTasks.add(exceptionAndTasks); + isRunning.set(false); + } finally { + clear(); + } + } + + private void performActionsOnTasks() throws InterruptedException { + tasksAndActionsLock.lock(); + try { + for (final TaskAndAction taskAndAction : getTasksAndActions()) { + final Task task = taskAndAction.task; + final Action action = taskAndAction.action; + switch (action) { + case ADD: + addTask(task); + break; + } + } + } finally { + tasksAndActionsLock.unlock(); + } + } + + private void restoreTasks() throws InterruptedException { + try { + // ToDo: Prioritize restoration of active tasks over standby tasks + // changelogReader.enforceRestoreActive(); + changelogReader.restore(updatingTasks); + } catch (final TaskCorruptedException taskCorruptedException) { + handleTaskCorruptedException(taskCorruptedException); + } catch (final StreamsException streamsException) { + handleStreamsException(streamsException); + } + final Set<TopicPartition> completedChangelogs = changelogReader.completedChangelogs(); + final List<Task> activeTasks = updatingTasks.values().stream().filter(Task::isActive).collect(Collectors.toList()); + for (final Task task : activeTasks) { + endRestorationIfChangelogsCompletelyRead(task, completedChangelogs); + } + } + + private void handleTaskCorruptedException(final TaskCorruptedException taskCorruptedException) { + final Set<TaskId> corruptedTaskIds = taskCorruptedException.corruptedTasks(); + final Set<Task> corruptedTasks = new HashSet<>(); + for (final TaskId taskId : corruptedTaskIds) { + final Task corruptedTask = updatingTasks.remove(taskId); + if (corruptedTask == null) { + throw new IllegalStateException("Task " + taskId + " is corrupted but is not updating. " + BUG_ERROR_MESSAGE); + } + corruptedTasks.add(corruptedTask); + } + failedTasks.add(new ExceptionAndTasks(corruptedTasks, taskCorruptedException)); + } + + private void handleStreamsException(final StreamsException streamsException) { + final ExceptionAndTasks exceptionAndTasks; + if (streamsException.taskId().isPresent()) { + exceptionAndTasks = handleStreamsExceptionWithTask(streamsException); + } else { + exceptionAndTasks = handleStreamsExceptionWithoutTask(streamsException); + } + failedTasks.add(exceptionAndTasks); + } + + private ExceptionAndTasks handleStreamsExceptionWithTask(final StreamsException streamsException) { + final TaskId failedTaskId = streamsException.taskId().get(); + if (!updatingTasks.containsKey(failedTaskId)) { + throw new IllegalStateException("Task " + failedTaskId + " failed but is not updating. " + BUG_ERROR_MESSAGE); + } + final Set<Task> failedTask = new HashSet<>(); + failedTask.add(updatingTasks.get(failedTaskId)); + updatingTasks.remove(failedTaskId); + return new ExceptionAndTasks(failedTask, streamsException); + } + + private ExceptionAndTasks handleStreamsExceptionWithoutTask(final StreamsException streamsException) { + final ExceptionAndTasks exceptionAndTasks = new ExceptionAndTasks(new HashSet<>(updatingTasks.values()), streamsException); + updatingTasks.clear(); + return exceptionAndTasks; + } + + private void waitIfAllChangelogsCompletelyRead() throws InterruptedException { + if (isRunning.get() && changelogReader.allChangelogsCompleted()) { + tasksAndActionsLock.lock(); + try { + while (tasksAndActions.isEmpty()) { + tasksAndActionsCondition.await(); + } + } finally { + tasksAndActionsLock.unlock(); + } + } + } + + private void clear() { + tasksAndActionsLock.lock(); + restoredActiveTasksLock.lock(); + try { + tasksAndActions.clear(); + restoredActiveTasks.clear(); + } finally { + tasksAndActionsLock.unlock(); + restoredActiveTasksLock.unlock(); + } + changelogReader.clear(); + updatingTasks.clear(); + } + + private List<TaskAndAction> getTasksAndActions() { + final List<TaskAndAction> tasksAndActionsToProcess = new ArrayList<>(tasksAndActions); + tasksAndActions.clear(); + return tasksAndActionsToProcess; + } + + private void addTask(final Task task) { + if (isStateless(task)) { + addTaskToRestoredTasks((StreamTask) task); + } else { + updatingTasks.put(task.id(), task); + } + } + + private boolean isStateless(final Task task) { + return task.changelogPartitions().isEmpty() && task.isActive(); + } + + private void endRestorationIfChangelogsCompletelyRead(final Task task, + final Set<TopicPartition> restoredChangelogs) { + final Collection<TopicPartition> taskChangelogPartitions = task.changelogPartitions(); + if (restoredChangelogs.containsAll(taskChangelogPartitions)) { + task.completeRestoration(offsetResetter); + addTaskToRestoredTasks((StreamTask) task); + updatingTasks.remove(task.id()); + } + } + + private void addTaskToRestoredTasks(final StreamTask task) { + restoredActiveTasksLock.lock(); + try { + restoredActiveTasks.add(task); + restoredActiveTasksCondition.signalAll(); + } finally { + restoredActiveTasksLock.unlock(); + } + } + } + + enum Action { + ADD + } + + private static class TaskAndAction { + public final Task task; + public final Action action; + + public TaskAndAction(final Task task, final Action action) { + this.task = task; + this.action = action; + } + } + + private final Time time; + private final ChangelogReader changelogReader; + private final java.util.function.Consumer<Set<TopicPartition>> offsetResetter; + private final Queue<TaskAndAction> tasksAndActions = new LinkedList<>(); + private final Lock tasksAndActionsLock = new ReentrantLock(); + private final Condition tasksAndActionsCondition = tasksAndActionsLock.newCondition(); + private final Queue<StreamTask> restoredActiveTasks = new LinkedList<>(); + private final Lock restoredActiveTasksLock = new ReentrantLock(); Review Comment: And also as a wild, meta thought (maybe we've discussed about this.. I cannot remember clearly): what if we just make all three communication channels as blocking queues, instead of one blocking queue and two pairs of queue+locks? More specifically: 1) in the updater's iteration, it would just try to `drainTo` everything, in best effort, from the action queue. It's okay if we did not actually drain everything with a single call. 2) in the main thread, it would similarly just try to `drainTo` the failed and completed tasks, and we do not use a `timeout` in the `getRestoredActiveTasks` (maybe there's a reason that a blocking with timeout is preferred, just lmk). 3) the tricky part is `getAllTasks`; for that maybe we can have a single global read-write lock, and all other functions just try to grab `read` lock, and this function grabs the `write` lock. -- 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. 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