mjsax commented on code in PR #16922:
URL: https://github.com/apache/kafka/pull/16922#discussion_r1733759515
##########
streams/src/main/java/org/apache/kafka/streams/processor/internals/StateDirectory.java:
##########
@@ -182,6 +206,118 @@ 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());
+
+ 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();
+
+ 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() >=
numStreamThreads.get()) {
Review Comment:
While the `KafkaStreams#threads` variable is a synchronized list, I am still
wondering about a race condition?
We call `KafkaStreams#start()` and the `StreamsThreads` do stuff in the
background, and the rebalance step executes, and all threads might call
`closeInitialTasksIfLastAssginedThread` concurrently. In parallel,
`addStreamThread()` could be called, modifying (increase) the thread count
breaking this condition? Or would it eventually fix itself, because the new
`StreamsThreads` would trigger another rebalance, and thus we would execute
this again, and would close "dandling tasks" eventually)?
Btw: also wondering about `threadsWithAssignment` -- if we have more threads
than tasks, and some threads don't get anything assigned, could this become an
issue? Or would the rebalance callback get executed in a way such that we call
`closeInitialTasksIfLastAssginedThread` even if nothing is assigned to a thread?
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