nicktelford commented on code in PR #16922:
URL: https://github.com/apache/kafka/pull/16922#discussion_r1732613492
##########
streams/src/main/java/org/apache/kafka/streams/processor/internals/StateDirectory.java:
##########
@@ -182,6 +199,120 @@ private boolean lockStateDirectory() {
return stateDirLock != null;
}
+ public void initializeTasksForLocalState(final TopologyMetadata
topologyMetadata, final StreamsMetricsImpl streamsMetrics) {
+ final List<TaskDirectory> nonEmptyTaskDirectories =
listNonEmptyTaskDirectories();
+ if (hasPersistentStores && !nonEmptyTaskDirectories.isEmpty()) {
+ final LogContext logContext = new LogContext("main-thread ");
+ final ThreadCache dummyCache = new ThreadCache(logContext, 0,
streamsMetrics);
+ final boolean eosEnabled = StreamsConfigUtils.eosEnabled(config);
+ final boolean stateUpdaterEnabled =
StreamsConfig.InternalConfig.stateUpdaterEnabled(config.originals());
+
+ // discover all non-empty task directories in StateDirectory
+ for (final TaskDirectory taskDirectory : nonEmptyTaskDirectories) {
+ final String dirName = taskDirectory.file().getName();
+ final TaskId id = parseTaskDirectoryName(dirName,
taskDirectory.namedTopology());
+ final ProcessorTopology topology =
topologyMetadata.buildSubtopology(id);
+ final Set<TopicPartition> inputPartitions =
topology.sourceTopics().stream().map(topic -> new TopicPartition(topic,
id.partition())).collect(Collectors.toSet());
+
+ // create a StandbyTask for each one
+ if (topology.hasStateWithChangelogs()) {
+ final ProcessorStateManager stateManager = new
ProcessorStateManager(
+ id,
+ Task.TaskType.STANDBY,
+ eosEnabled,
+ logContext,
+ this,
+ null,
+ topology.storeToChangelogTopic(),
+ inputPartitions,
+ stateUpdaterEnabled
+ );
+
+ final InternalProcessorContext<Object, Object> context =
new ProcessorContextImpl(
+ id,
+ config,
+ stateManager,
+ streamsMetrics,
+ dummyCache
+ );
+
+ final Task task = new StandbyTask(
+ id,
+ inputPartitions,
+ topology,
+ topologyMetadata.taskConfig(id),
+ streamsMetrics,
+ stateManager,
+ this,
+ dummyCache,
+ context
+ );
+
+ // initialize and suspend new Tasks
+ try {
+ task.initializeIfNeeded();
+ task.suspend();
+
+ // add new Tasks to tasksForLocalState
+ tasksForLocalState.put(id, task);
+ } catch (final TaskCorruptedException e) {
+ // Task is corrupt - wipe it out (under EOS) and don't
initialize a Standby for it
+ task.suspend();
+ task.closeDirty();
+ }
+ }
+ }
+ }
+ }
+
+ public boolean hasInitialTasks() {
+ return !tasksForLocalState.isEmpty();
+ }
+
+ public Task assignInitialTask(final TaskId taskId) {
+ final Task task = tasksForLocalState.remove(taskId);
+ if (task != null) {
+ lockedTasksToOwner.replace(taskId, Thread.currentThread());
+ }
+ return task;
+ }
+
+ public void closeInitialTasksIfLastAssginedThread() {
+ if (hasInitialTasks() && threadsWithAssignment.incrementAndGet() >=
config.getInt(StreamsConfig.NUM_STREAM_THREADS_CONFIG)) {
+ // we need to be careful here, because other StreamThreads may
still be assigning tasks (via assignInitialTask)
+ // so we first "drain" our Map of all remaining Tasks, and then
close all the Tasks we successfully claimed from the Map
+ final Set<Task> tasksToClose = drainInitialTasks();
+ for (final Task task : tasksToClose) {
+ task.closeClean();
+ }
+ }
+ }
+
+ private void closeRemainingInitialTasks() {
+ closeRemainingInitialTasks(t -> true);
+ }
+
+ private void closeRemainingInitialTasks(final Predicate<Task> predicate) {
+ final Set<Task> drainedTasks = drainInitialTasks(predicate);
+ for (final Task task : drainedTasks) {
+ task.closeClean();
+ }
+ }
+
+ private Set<Task> drainInitialTasks() {
+ return drainInitialTasks(t -> true);
+ }
+
+ private Set<Task> drainInitialTasks(final Predicate<Task> predicate) {
+ final Set<Task> drainedTasks = new
HashSet<>(tasksForLocalState.size());
+ for (final Map.Entry<TaskId, Task> entry :
tasksForLocalState.entrySet()) {
+ if (predicate.test(entry.getValue()) &&
tasksForLocalState.remove(entry.getKey()) != null) {
Review Comment:
This method can be called from multiple threads, during `close()`.
They can be iterating and removing elements from `tasksForLocalState` at the
same time, so we therefore need to ensure that this is done atomically, and
that each thread only "drains" the Task that it removed from the collection,
and not any Tasks that another thread removed first.
This is safe, because `tasksForLocalState` is a `ConcurrentHashMap`, which
guarantees atomicity of `remove` and iteration of `entrySet`.
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