cadonna commented on code in PR #13925:
URL: https://github.com/apache/kafka/pull/13925#discussion_r1245477150
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streams/src/main/java/org/apache/kafka/streams/processor/internals/TaskManager.java:
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@@ -1138,28 +1138,33 @@ public void signalResume() {
public Map<TaskId, Long> getTaskOffsetSums() {
final Map<TaskId, Long> taskOffsetSums = new HashMap<>();
- // Not all tasks will create directories, and there may be directories
for tasks we don't currently own,
- // so we consider all tasks that are either owned or on disk. This
includes stateless tasks, which should
- // just have an empty changelogOffsets map.
- for (final TaskId id : union(HashSet::new, lockedTaskDirectories,
tasks.allTaskIds())) {
- final Task task = tasks.contains(id) ? tasks.task(id) : null;
- // Closed and uninitialized tasks don't have any offsets so we
should read directly from the checkpoint
- if (task != null && task.state() != State.CREATED && task.state()
!= State.CLOSED) {
+ final Map<TaskId, Task> tasks = allTasks();
+ final Set<TaskId>
lockedTaskDirectoriesOfNonOwnedTasksAndClosedAndCreatedTasks =
Review Comment:
I do not think there is guarantee that `lockedTaskDirectories` contains any
tasks the client owns. `lockedTaskDirectories` are just the non-empty task
directories in the state directory when a rebalance starts. However, a task
directory is created when a task is created, i.e., it is in state `CREATE`. A
task directory is not deleted when a task is closed, i.e., in state `CLOSED`.
This might be a correlation and not a thought-out invariant. At least, the
original code did not rely on this since it used `union(HashSet::new,
lockedTaskDirectories, tasks.allTaskIds())`.
I am also somehow reluctant to rely on such -- IMO -- brittle invariant.
As an example, in future we could decide to move the creation of the task
directory to other parts of the code -- like when the task is initialized --
which would mean that there is a interval in which the task is in state
`CREATED` but does not have a task directory.
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