[FLINK-19286][runtime] Improve region sorting performance

is · Sep 23, 2020 · 247e452 · 247e452
1 parent f89c137
commit 247e452
Showing 1 changed file with 9 additions and 0 deletions.
diff --git a/...me/src/main/java/org/apache/flink/runtime/scheduler/strategy/SchedulingStrategyUtils.java b/...me/src/main/java/org/apache/flink/runtime/scheduler/strategy/SchedulingStrategyUtils.java
@@ -24,6 +24,7 @@
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.Set;
 import java.util.function.Function;
@@ -81,6 +82,14 @@ static List<SchedulingPipelinedRegion> sortPipelinedRegionsInTopologicalOrder(
  final SchedulingTopology topology,
  final Set<SchedulingPipelinedRegion> regions) {
 
+ // Avoid the O(V) (V is the number of vertices in the topology) sorting
+ // complexity if the given set of regions is small enough
+ if (regions.size() == 0) {
+ return Collections.emptyList();
+ } else if (regions.size() == 1) {
+ return Collections.singletonList(regions.iterator().next());
+ }
+
  return IterableUtils.toStream(topology.getVertices())
  .map(SchedulingExecutionVertex::getId)
  .map(topology::getPipelinedRegionOfVertex)