supervisor/autoscaler: Fix clearing of collected lags on skipped scale actions (#17356)

* superviosr/autoscaler: Fix clearing of collected lags on skipped scale actions

* comments

* supervisor/autoscaler: Skip scaling when partitions are less than minTaskCount (#17335)

* Fix pip installation after ubuntu upgrade (#17358)

* fix tests

---------

Co-authored-by: Pranav <pranavbhole@gmail.com>

extensions-core/kinesis-indexing-service/src/test/java/org/apache/druid/indexing/kinesis/supervisor/KinesisSupervisorTest.java

@@ -358,6 +358,7 @@ public class KinesisSupervisorTest extends EasyMockSupport
     Thread.sleep(1 * 1000);
     int taskCountAfterScale = supervisor.getIoConfig().getTaskCount();
     Assert.assertEquals(2, taskCountAfterScale);
+    autoscaler.stop();
   }
 
   @Test
@@ -435,6 +436,7 @@ public class KinesisSupervisorTest extends EasyMockSupport
     Thread.sleep(1 * 1000);
     int taskCountAfterScale = supervisor.getIoConfig().getTaskCount();
     Assert.assertEquals(1, taskCountAfterScale);
+    autoscaler.stop();
   }
 
   @Test

indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/supervisor/SeekableStreamSupervisor.java

@@ -422,13 +422,19 @@ public abstract class SeekableStreamSupervisor<PartitionIdType, SequenceOffsetTy
   // change taskCount without resubmitting.
   private class DynamicAllocationTasksNotice implements Notice
   {
-    Callable<Integer> scaleAction;
+    Callable<Integer> computeDesiredTaskCount;
     ServiceEmitter emitter;
+    Runnable onSuccessfulScale;
     private static final String TYPE = "dynamic_allocation_tasks_notice";
 
-    DynamicAllocationTasksNotice(Callable<Integer> scaleAction, ServiceEmitter emitter)
+    DynamicAllocationTasksNotice(
+        Callable<Integer> computeDesiredTaskCount,
+        Runnable onSuccessfulScale,
+        ServiceEmitter emitter
+    )
     {
-      this.scaleAction = scaleAction;
+      this.computeDesiredTaskCount = computeDesiredTaskCount;
+      this.onSuccessfulScale = onSuccessfulScale;
       this.emitter = emitter;
     }
 
@@ -470,7 +476,7 @@ public abstract class SeekableStreamSupervisor<PartitionIdType, SequenceOffsetTy
               return;
             }
           }
-          final Integer desiredTaskCount = scaleAction.call();
+          final Integer desiredTaskCount = computeDesiredTaskCount.call();
           ServiceMetricEvent.Builder event = ServiceMetricEvent.builder()
               .setDimension(DruidMetrics.DATASOURCE, dataSource)
               .setDimension(DruidMetrics.STREAM, getIoConfig().getStream());
@@ -500,6 +506,7 @@ public abstract class SeekableStreamSupervisor<PartitionIdType, SequenceOffsetTy
 
           boolean allocationSuccess = changeTaskCount(desiredTaskCount);
           if (allocationSuccess) {
+            onSuccessfulScale.run();
             dynamicTriggerLastRunTime = nowTime;
           }
         }
@@ -1260,9 +1267,13 @@ public abstract class SeekableStreamSupervisor<PartitionIdType, SequenceOffsetTy
     }
   }
 
-  public Runnable buildDynamicAllocationTask(Callable<Integer> scaleAction, ServiceEmitter emitter)
+  public Runnable buildDynamicAllocationTask(
+      Callable<Integer> scaleAction,
+      Runnable onSuccessfulScale,
+      ServiceEmitter emitter
+  )
   {
-    return () -> addNotice(new DynamicAllocationTasksNotice(scaleAction, emitter));
+    return () -> addNotice(new DynamicAllocationTasksNotice(scaleAction, onSuccessfulScale, emitter));
   }
 
   private Runnable buildRunTask()

indexing-service/src/main/java/org/apache/druid/indexing/seekablestream/supervisor/autoscaler/LagBasedAutoScaler.java

@@ -86,10 +86,6 @@ public class LagBasedAutoScaler implements SupervisorTaskAutoScaler
       int desiredTaskCount = -1;
       try {
         desiredTaskCount = computeDesiredTaskCount(new ArrayList<>(lagMetricsQueue));
-
-        if (desiredTaskCount != -1) {
-          lagMetricsQueue.clear();
-        }
       }
       catch (Exception ex) {
         log.warn(ex, "Exception while computing desired task count for [%s]", dataSource);
@@ -100,6 +96,19 @@ public class LagBasedAutoScaler implements SupervisorTaskAutoScaler
       return desiredTaskCount;
     };
 
+    Runnable onSuccessfulScale = () -> {
+      LOCK.lock();
+      try {
+        lagMetricsQueue.clear();
+      }
+      catch (Exception ex) {
+        log.warn(ex, "Exception while clearing lags for [%s]", dataSource);
+      }
+      finally {
+        LOCK.unlock();
+      }
+    };
+
     lagComputationExec.scheduleAtFixedRate(
         computeAndCollectLag(),
         lagBasedAutoScalerConfig.getScaleActionStartDelayMillis(), // wait for tasks to start up
@@ -107,7 +116,7 @@ public class LagBasedAutoScaler implements SupervisorTaskAutoScaler
         TimeUnit.MILLISECONDS
     );
     allocationExec.scheduleAtFixedRate(
-        supervisor.buildDynamicAllocationTask(scaleAction, emitter),
+        supervisor.buildDynamicAllocationTask(scaleAction, onSuccessfulScale, emitter),
         lagBasedAutoScalerConfig.getScaleActionStartDelayMillis() + lagBasedAutoScalerConfig
             .getLagCollectionRangeMillis(),
         lagBasedAutoScalerConfig.getScaleActionPeriodMillis(),