tim-patterson commented on a change in pull request #11493:
URL: https://github.com/apache/kafka/pull/11493#discussion_r810597642
##########
File path:
streams/src/main/java/org/apache/kafka/streams/processor/internals/StreamsPartitionAssignor.java
##########
@@ -1029,104 +1041,148 @@ private boolean addClientAssignments(final
Set<TaskId> statefulTasks,
/**
* Generate an assignment that tries to preserve thread-level stickiness
of stateful tasks without violating
- * balance. The stateful and total task load are both balanced across
threads. Tasks without previous owners
- * will be interleaved by group id to spread subtopologies across threads
and further balance the workload.
+ * balance. The tasks are balanced across threads. Tasks without previous
owners will be interleaved by
+ * group id to spread subtopologies across threads and further balance the
workload.
+ * threadLoad is a map that keeps track of task load per thread across
multiple calls so actives and standbys
+ * are evenly distributed
*/
- static Map<String, List<TaskId>> assignTasksToThreads(final
Collection<TaskId> statefulTasksToAssign,
- final
Collection<TaskId> statelessTasksToAssign,
- final
SortedSet<String> consumers,
- final ClientState
state) {
+ static Map<String, List<TaskId>> assignStatefulTasksToThreads(final
Collection<TaskId> tasksToAssign,
+ final
SortedSet<String> consumers,
+ final
ClientState state,
+ final
Map<String, Integer> threadLoad) {
final Map<String, List<TaskId>> assignment = new HashMap<>();
for (final String consumer : consumers) {
assignment.put(consumer, new ArrayList<>());
}
- final List<TaskId> unassignedStatelessTasks = new
ArrayList<>(statelessTasksToAssign);
- Collections.sort(unassignedStatelessTasks);
-
- final Iterator<TaskId> unassignedStatelessTasksIter =
unassignedStatelessTasks.iterator();
+ int totalTasks = tasksToAssign.size();
+ for (final Integer threadTaskCount : threadLoad.values()) {
+ totalTasks += threadTaskCount;
+ }
- final int minStatefulTasksPerThread = (int) Math.floor(((double)
statefulTasksToAssign.size()) / consumers.size());
- final PriorityQueue<TaskId> unassignedStatefulTasks = new
PriorityQueue<>(statefulTasksToAssign);
+ final int minTasksPerThread = (int) Math.floor(((double) totalTasks) /
consumers.size());
+ final PriorityQueue<TaskId> unassignedTasks = new
PriorityQueue<>(tasksToAssign);
final Queue<String> consumersToFill = new LinkedList<>();
// keep track of tasks that we have to skip during the first pass in
case we can reassign them later
// using tree-map to make sure the iteration ordering over keys are
preserved
final Map<TaskId, String> unassignedTaskToPreviousOwner = new
TreeMap<>();
- if (!unassignedStatefulTasks.isEmpty()) {
- // First assign stateful tasks to previous owner, up to the min
expected tasks/thread
+ if (!unassignedTasks.isEmpty()) {
+ // First assign tasks to previous owner, up to the min expected
tasks/thread
for (final String consumer : consumers) {
final List<TaskId> threadAssignment = assignment.get(consumer);
for (final TaskId task : state.prevTasksByLag(consumer)) {
- if (unassignedStatefulTasks.contains(task)) {
- if (threadAssignment.size() <
minStatefulTasksPerThread) {
+ if (unassignedTasks.contains(task)) {
+ final int threadTaskCount = threadAssignment.size() +
threadLoad.getOrDefault(consumer, 0);
+ if (threadTaskCount < minTasksPerThread) {
threadAssignment.add(task);
- unassignedStatefulTasks.remove(task);
+ unassignedTasks.remove(task);
} else {
unassignedTaskToPreviousOwner.put(task, consumer);
}
}
}
- if (threadAssignment.size() < minStatefulTasksPerThread) {
+ final int threadTaskCount = threadAssignment.size() +
threadLoad.getOrDefault(consumer, 0);
+ if (threadTaskCount < minTasksPerThread) {
consumersToFill.offer(consumer);
}
}
// Next interleave remaining unassigned tasks amongst unfilled
consumers
while (!consumersToFill.isEmpty()) {
- final TaskId task = unassignedStatefulTasks.poll();
+ final TaskId task = unassignedTasks.poll();
if (task != null) {
final String consumer = consumersToFill.poll();
final List<TaskId> threadAssignment =
assignment.get(consumer);
threadAssignment.add(task);
- if (threadAssignment.size() < minStatefulTasksPerThread) {
+ final int threadTaskCount = threadAssignment.size() +
threadLoad.getOrDefault(consumer, 0);
+ if (threadTaskCount < minTasksPerThread) {
consumersToFill.offer(consumer);
}
} else {
throw new TaskAssignmentException("Ran out of unassigned
stateful tasks but some members were not at capacity");
}
}
- // At this point all consumers are at the min capacity, so there
may be up to N - 1 unassigned
- // stateful tasks still remaining that should now be distributed
over the consumers
- if (!unassignedStatefulTasks.isEmpty()) {
- consumersToFill.addAll(consumers);
+ // At this point all consumers are at the min or min + 1 capacity,
+ // the tasks still remaining that should now be distributed over
the consumers that are still
+ // at min capacity
+ if (!unassignedTasks.isEmpty()) {
+ for (final String consumer : consumers) {
+ final int taskCount = assignment.get(consumer).size() +
threadLoad.getOrDefault(consumer, 0);
+ if (taskCount == minTasksPerThread) {
+ consumersToFill.add(consumer);
+ }
+ }
// Go over the tasks we skipped earlier and assign them to
their previous owner when possible
for (final Map.Entry<TaskId, String> taskEntry :
unassignedTaskToPreviousOwner.entrySet()) {
final TaskId task = taskEntry.getKey();
final String consumer = taskEntry.getValue();
- if (consumersToFill.contains(consumer) &&
unassignedStatefulTasks.contains(task)) {
+ if (consumersToFill.contains(consumer) &&
unassignedTasks.contains(task)) {
assignment.get(consumer).add(task);
- unassignedStatefulTasks.remove(task);
+ unassignedTasks.remove(task);
// Remove this consumer since we know it is now at
minCapacity + 1
consumersToFill.remove(consumer);
}
}
// Now just distribute the remaining unassigned stateful tasks
over the consumers still at min capacity
- for (final TaskId task : unassignedStatefulTasks) {
+ for (final TaskId task : unassignedTasks) {
final String consumer = consumersToFill.poll();
final List<TaskId> threadAssignment =
assignment.get(consumer);
threadAssignment.add(task);
}
+ }
+ }
+ // Update threadLoad
+ for (final Map.Entry<String, List<TaskId>> taskEntry :
assignment.entrySet()) {
+ final String consumer = taskEntry.getKey();
+ final int totalCount = threadLoad.getOrDefault(consumer, 0) +
taskEntry.getValue().size();
+ threadLoad.put(consumer, totalCount);
+ }
+ return assignment;
+ }
- // There must be at least one consumer still at min capacity
while all the others are at min
- // capacity + 1, so start distributing stateless tasks to get
all consumers back to the same count
- while (unassignedStatelessTasksIter.hasNext()) {
- final String consumer = consumersToFill.poll();
- if (consumer != null) {
- final TaskId task =
unassignedStatelessTasksIter.next();
- unassignedStatelessTasksIter.remove();
- assignment.get(consumer).add(task);
- } else {
- break;
- }
- }
+ static Map<String, List<TaskId>> assignStatelessTasksToThreads(final
Collection<TaskId> statelessTasksToAssign,
+ final
SortedSet<String> consumers,
+ final
Map<String, Integer> threadLoad) {
+ final List<TaskId> tasksToAssign = new
ArrayList<>(statelessTasksToAssign);
+ Collections.sort(tasksToAssign);
+ final Map<String, List<TaskId>> assignment = new HashMap<>();
+ for (final String consumer : consumers) {
+ assignment.put(consumer, new ArrayList<>());
+ }
+
+ int maxThreadLoad = 0;
+ for (final int load : threadLoad.values()) {
+ maxThreadLoad = Integer.max(maxThreadLoad, load);
Review comment:
Let me know what you think of the latest commit.
Instead of gluing the methods together I just got rid of
`assignStatelessTasksToThreads`, the only real difference between the two
methods was the stateful one trying to be sticky.
I just passed in a boolean to control the part of the method that does the
stickiness stuff.
--
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: jira-unsubscr...@kafka.apache.org
For queries about this service, please contact Infrastructure at:
us...@infra.apache.org
