Change tagged job assignment behavior

Once tag removed from instance for assignment purpose, current behavior is:
1) no new tagged tasks assigns to that instance.
2) drop the existing running tasks.

Change behavior for this:
1) keep no new tagged tasks assigns to that instance.
2) let existing tasks running to complete

Test added.

helix-core/src/main/java/org/apache/helix/task/AbstractTaskDispatcher.java

@@ -825,14 +825,19 @@ private Set<Integer> filterTasks(String jobResource, Iterable<Integer> allPartit
           // disabled. If instance is disabled and current state still exist on the instance,
           // then controller needs to drop the current state, otherwise, the task can be marked as
           // dropped and be reassigned to other instances
-          if (disableInstances.contains(assignedParticipant)
-              && currStateOutput.getCurrentState(jobResource, new Partition(partitionName),
+          if (disableInstances.contains(assignedParticipant) &&
+              currStateOutput.getCurrentState(jobResource, new Partition(partitionName),
                   assignedParticipant) != null) {
             paMap.put(partitionNumber,
                 new PartitionAssignment(assignedParticipant, TaskPartitionState.DROPPED.name()));
           } else {
-            jobContext.setPartitionState(partitionNumber, TaskPartitionState.DROPPED);
-            filteredTasks.add(partitionNumber);
+            if (_manager.getHelixDataAccessor().getProperty(
+                _manager.getHelixDataAccessor().keyBuilder().instanceConfig(assignedParticipant))
+                == null) {
+              // Only drop the task if the instance is not alive, otherwise, the task will be continued
+              jobContext.setPartitionState(partitionNumber, TaskPartitionState.DROPPED);
+              filteredTasks.add(partitionNumber);
+            }
           }
         }
       }

helix-core/src/main/java/org/apache/helix/task/JobDispatcher.java

@@ -240,7 +240,8 @@ private ResourceAssignment computeResourceMapping(String jobResource,
     Map<String, Set<Integer>> tasksToDrop = new HashMap<>();
 
     Map<String, SortedSet<Integer>> currentInstanceToTaskAssignments =
-        getCurrentInstanceToTaskAssignments(liveInstances, currStateOutput, jobResource, tasksToDrop);
+        getCurrentInstanceToTaskAssignments(cache.getEnabledLiveInstances(), currStateOutput,
+            jobResource, tasksToDrop);
 
     updateInstanceToTaskAssignmentsFromContext(jobCtx, currentInstanceToTaskAssignments);
 

helix-core/src/test/java/org/apache/helix/task/TestJobTagRemoval.java

@@ -0,0 +1,76 @@
+package org.apache.helix.task;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import com.google.common.collect.ImmutableMap;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.helix.ConfigAccessor;
+import org.apache.helix.integration.task.MockTask;
+import org.apache.helix.integration.task.TaskTestBase;
+import org.apache.helix.model.InstanceConfig;
+import org.testng.Assert;
+import org.testng.annotations.Test;
+
+public class TestJobTagRemoval extends TaskTestBase {
+
+  @Test
+  public void testJobTagRemoval() throws InterruptedException {
+    String TEST_TAG = "testTag";
+
+    ConfigAccessor configAccessor = new ConfigAccessor(_gZkClient);
+    InstanceConfig cfg =
+        configAccessor.getInstanceConfig(CLUSTER_NAME, _participants[0].getInstanceName());
+    cfg.addTag(TEST_TAG);
+    configAccessor.setInstanceConfig(CLUSTER_NAME, _participants[0].getInstanceName(), cfg);
+
+    Workflow.Builder builder = new Workflow.Builder("testWorkflow");
+    List<TaskConfig> taskConfigs = new ArrayList<>();
+    taskConfigs.add(
+        new TaskConfig.Builder().setTaskId("tagged_task").setCommand(MockTask.TASK_COMMAND)
+            .build());
+    JobConfig.Builder jobBuilder = new JobConfig.Builder().addTaskConfigs(taskConfigs)
+        .setJobCommandConfigMap(ImmutableMap.of(MockTask.JOB_DELAY, "5000"))
+        .setInstanceGroupTag(TEST_TAG);
+    JobConfig.Builder jobBuilder1 = new JobConfig.Builder().addTaskConfigs(taskConfigs)
+        .setJobCommandConfigMap(ImmutableMap.of(MockTask.JOB_DELAY, "1000"))
+        .setInstanceGroupTag(TEST_TAG);
+    builder.addJob("JOB0", jobBuilder);
+    builder.addJob("JOB1", jobBuilder1);
+    builder.addParentChildDependency("JOB0", "JOB1");
+    _driver.start(builder.build());
+
+    // Wait for the job to be created
+    _driver.pollForJobState("testWorkflow", "testWorkflow_JOB0", TaskState.IN_PROGRESS);
+
+    // Remove the tag
+    cfg = configAccessor.getInstanceConfig(CLUSTER_NAME, _participants[0].getInstanceName());
+    cfg.removeTag(TEST_TAG);
+    configAccessor.setInstanceConfig(CLUSTER_NAME, _participants[0].getInstanceName(), cfg);
+
+    // Wait for the job to complete
+    _driver.pollForJobState("testWorkflow", "testWorkflow_JOB0", TaskState.COMPLETED);
+    _driver.pollForJobState("testWorkflow", "testWorkflow_JOB1", TaskState.IN_PROGRESS);
+    JobContext ctx = _driver.getJobContext("testWorkflow_JOB1");
+    Assert.assertEquals(ctx.getPartitionState(0), null);
+  }
+}