mxm commented on code in PR #879:
URL:
https://github.com/apache/flink-kubernetes-operator/pull/879#discussion_r1757005246
##########
flink-autoscaler/src/main/java/org/apache/flink/autoscaler/JobVertexScaler.java:
##########
@@ -389,15 +413,51 @@ protected static int scale(
return newParallelism;
}
- // When the shuffle type of vertex inputs contains keyBy or vertex is
a source, we try to
- // adjust the parallelism such that it divides the maxParallelism
without a remainder
- // => data is evenly spread across subtasks
- for (int p = newParallelism; p <= maxParallelism / 2 && p <=
upperBound; p++) {
- if (maxParallelism % p == 0) {
+ int adjustableMaxParallelism = maxParallelism;
+ int adjustableUpperBound;
+ if (numPartitions <= 0) {
+ adjustableUpperBound = Math.min(maxParallelism / 2, upperBound);
+ } else {
+ adjustableUpperBound = Math.min(numPartitions, upperBound);
+ adjustableMaxParallelism = numPartitions;
+ }
+
+ // When the shuffle type of vertex inputs contains keyBy or vertex is
a source,
+ // we try to adjust the parallelism such that it divides
+ // the adjustableMaxParallelism without a remainder => data is evenly
spread across subtasks
+ for (int p = newParallelism; p <= adjustableUpperBound; p++) {
+ if (adjustableMaxParallelism % p == 0) {
return p;
}
}
+ if (numPartitions > 0) {
+
+ // When adjust the parallelism after rounding up cannot be evenly
divided by source
+ // numPartitions, Try to find the smallest parallelism that can
satisfy the current
+ // consumption rate.
+ int finalParallelism = newParallelism;
+ for (; finalParallelism > parallelismLowerLimit;
finalParallelism--) {
+ if (numPartitions / finalParallelism > numPartitions /
newParallelism) {
+ if (numPartitions % finalParallelism != 0) {
+ finalParallelism++;
+ }
+ break;
+ }
+ }
+ consumer.accept(
+ String.format(
+ SCALE_LIMITED_MESSAGE_FORMAT,
+ vertex,
+ newParallelism,
+ finalParallelism,
+ String.format(
+ "numPartitions :
%s,upperBound(maxParallelism or parallelismUpperLimit): %s, "
+ + "parallelismLowerLimit: %s.",
+ numPartitions, upperBound,
parallelismLowerLimit)));
Review Comment:
I would prefer if we worked on the EventHandler directly here instead of
going through the consumer. The reason is that I would like to keep event
generation code in one place.
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