diff --git a/gui/admin-gui/src/main/java/com/evolveum/midpoint/web/page/admin/roles/AbstractRoleMemberPanel.java b/gui/admin-gui/src/main/java/com/evolveum/midpoint/web/page/admin/roles/AbstractRoleMemberPanel.java
index ca2d270f618..656ef496a95 100644
--- a/gui/admin-gui/src/main/java/com/evolveum/midpoint/web/page/admin/roles/AbstractRoleMemberPanel.java
+++ b/gui/admin-gui/src/main/java/com/evolveum/midpoint/web/page/admin/roles/AbstractRoleMemberPanel.java
@@ -69,7 +69,6 @@
 import com.evolveum.midpoint.web.component.MultifunctionalButton;
 import com.evolveum.midpoint.web.component.data.ISelectableDataProvider;
 import com.evolveum.midpoint.web.component.data.SelectableBeanObjectDataProvider;
-import com.evolveum.midpoint.web.component.data.column.ColumnUtils;
 import com.evolveum.midpoint.web.component.dialog.ChooseFocusTypeAndRelationDialogPanel;
 import com.evolveum.midpoint.web.component.dialog.ConfigureTaskConfirmationPanel;
 import com.evolveum.midpoint.web.component.form.MidpointForm;
@@ -1497,7 +1496,7 @@ protected PrismObject<TaskType> getTask(AjaxRequestTarget target) {
                 if (task == null) {
                     return null;
                 }
-                PrismObject<TaskType> recomputeTask = task.getClonedTaskObject();
+                PrismObject<TaskType> recomputeTask = task.getRawTaskObjectClone();
                 TaskType recomputeTaskType = recomputeTask.asObjectable();
                 recomputeTaskType.getAssignment().add(ObjectTypeUtil.createAssignmentTo(SystemObjectsType.ARCHETYPE_RECOMPUTATION_TASK.value(), ObjectTypes.ARCHETYPE, getPrismContext()));
                 return recomputeTask;
diff --git a/model/model-impl/src/main/java/com/evolveum/midpoint/model/impl/lens/projector/focus/AssignmentTripleEvaluator.java b/model/model-impl/src/main/java/com/evolveum/midpoint/model/impl/lens/projector/focus/AssignmentTripleEvaluator.java
index 1ccd7eee2f3..4c4f33689da 100644
--- a/model/model-impl/src/main/java/com/evolveum/midpoint/model/impl/lens/projector/focus/AssignmentTripleEvaluator.java
+++ b/model/model-impl/src/main/java/com/evolveum/midpoint/model/impl/lens/projector/focus/AssignmentTripleEvaluator.java
@@ -48,6 +48,8 @@
 
 import org.jetbrains.annotations.NotNull;
 
+import static com.evolveum.midpoint.util.DebugUtil.lazy;
+
 /**
  * Evaluates all assignments and sorts them to triple: added, removed and "kept" assignments.
  *
@@ -140,9 +142,8 @@ private Collection<AssignmentType> getVirtualAssignments() throws SchemaExceptio
                 beans.prismContext, task, result);
         LOGGER.trace("Forced assignments: {}", forcedAssignments);
 
-        if (LOGGER.isTraceEnabled()) {
-            LOGGER.trace("Task for process: {}", task.getUpdatedOrClonedTaskObject().debugDump());
-        }
+        LOGGER.trace("Task for process (operation result is not updated): {}",
+                lazy(() -> task.getRawTaskObjectClonedIfNecessary().debugDump()));
         Collection<Task> allTasksToRoot = task.getPathToRootTask(result);
         Collection<AssignmentType> taskAssignments = allTasksToRoot.stream()
                 .filter(Task::hasAssignments)
@@ -158,7 +159,7 @@ private Collection<AssignmentType> getVirtualAssignments() throws SchemaExceptio
     private AssignmentType createTaskAssignment(Task fromTask) {
         AssignmentType taskAssignment = new AssignmentType(beans.prismContext);
         ObjectReferenceType targetRef = new ObjectReferenceType();
-        targetRef.asReferenceValue().setObject(fromTask.getUpdatedOrClonedTaskObject());
+        targetRef.asReferenceValue().setObject(fromTask.getRawTaskObjectClonedIfNecessary());
         taskAssignment.setTargetRef(targetRef);
         return taskAssignment;
     }
diff --git a/model/model-impl/src/main/java/com/evolveum/midpoint/model/impl/scripting/VariablesUtil.java b/model/model-impl/src/main/java/com/evolveum/midpoint/model/impl/scripting/VariablesUtil.java
index 5538e343ca0..1bd67f409ed 100644
--- a/model/model-impl/src/main/java/com/evolveum/midpoint/model/impl/scripting/VariablesUtil.java
+++ b/model/model-impl/src/main/java/com/evolveum/midpoint/model/impl/scripting/VariablesUtil.java
@@ -77,7 +77,8 @@ static VariablesMap initialPreparation(VariablesMap initialVariables,
     }
 
     private static void addProvidedVariables(VariablesMap resultingVariables, VariablesMap initialVariables, Task task) {
-        TypedValue<TaskType> taskValAndDef = new TypedValue<>(task.getUpdatedOrClonedTaskObject().asObjectable(), task.getUpdatedOrClonedTaskObject().getDefinition());
+        PrismObject<TaskType> taskObject = task.getRawTaskObjectClonedIfNecessary();
+        TypedValue<TaskType> taskValAndDef = new TypedValue<>(taskObject.asObjectable(), taskObject.getDefinition());
         putImmutableValue(resultingVariables, ExpressionConstants.VAR_TASK, taskValAndDef);
         if (initialVariables != null) {
             initialVariables.forEach((key, value) -> putImmutableValue(resultingVariables, key, value));
diff --git a/model/model-test/src/main/java/com/evolveum/midpoint/model/test/AbstractModelIntegrationTest.java b/model/model-test/src/main/java/com/evolveum/midpoint/model/test/AbstractModelIntegrationTest.java
index fa5f2e815b8..aec80c3f3f6 100644
--- a/model/model-test/src/main/java/com/evolveum/midpoint/model/test/AbstractModelIntegrationTest.java
+++ b/model/model-test/src/main/java/com/evolveum/midpoint/model/test/AbstractModelIntegrationTest.java
@@ -3279,7 +3279,7 @@ protected void displayTaskWithOperationStats(String message, PrismObject<TaskTyp
     protected void displayTaskWithOperationStats(String message, Task task) throws SchemaException {
         display(message, task);
         String stats = prismContext.xmlSerializer()
-                .serializeRealValue(task.getUpdatedOrClonedTaskObject().asObjectable().getOperationStats(), TaskType.F_OPERATION_STATS);
+                .serializeRealValue(task.getStoredOperationStatsOrClone(), TaskType.F_OPERATION_STATS);
         displayValue(message + ": Operational stats", stats);
     }
 
@@ -3521,14 +3521,14 @@ public void timeout() {
     protected OperationResult waitForTaskTreeNextFinishedRun(String rootTaskOid, int timeout) throws Exception {
         final OperationResult waitResult = new OperationResult(AbstractIntegrationTest.class + ".waitForTaskTreeNextFinishedRun");
         Task origRootTask = taskManager.getTaskWithResult(rootTaskOid, waitResult);
-        return waitForTaskTreeNextFinishedRun(origRootTask.getUpdatedOrClonedTaskObject().asObjectable(), timeout, waitResult);
+        return waitForTaskTreeNextFinishedRun(origRootTask.getUpdatedTaskObject().asObjectable(), timeout, waitResult);
     }
 
     protected OperationResult runTaskTreeAndWaitForFinish(String rootTaskOid, int timeout) throws Exception {
         final OperationResult waitResult = new OperationResult(AbstractIntegrationTest.class + ".runTaskTreeAndWaitForFinish");
         Task origRootTask = taskManager.getTaskWithResult(rootTaskOid, waitResult);
         restartTask(rootTaskOid, waitResult);
-        return waitForTaskTreeNextFinishedRun(origRootTask.getUpdatedOrClonedTaskObject().asObjectable(), timeout, waitResult);
+        return waitForTaskTreeNextFinishedRun(origRootTask.getUpdatedTaskObject().asObjectable(), timeout, waitResult);
     }
 
     // a bit experimental
diff --git a/model/report-impl/src/main/java/com/evolveum/midpoint/report/impl/ReportJasperCreateTaskHandler.java b/model/report-impl/src/main/java/com/evolveum/midpoint/report/impl/ReportJasperCreateTaskHandler.java
index 5118b61eea0..1d6f660d6c4 100644
--- a/model/report-impl/src/main/java/com/evolveum/midpoint/report/impl/ReportJasperCreateTaskHandler.java
+++ b/model/report-impl/src/main/java/com/evolveum/midpoint/report/impl/ReportJasperCreateTaskHandler.java
@@ -591,7 +591,7 @@ void processPostReportScript(ReportType parentReport, String reportOutputFilePat
 
         VariablesMap variables = new VariablesMap();
         variables.put(ExpressionConstants.VAR_OBJECT, parentReport, parentReport.asPrismObject().getDefinition());
-        PrismObject<TaskType> taskObject = task.getUpdatedOrClonedTaskObject();
+        PrismObject<TaskType> taskObject = task.getRawTaskObjectClonedIfNecessary();
         variables.put(ExpressionConstants.VAR_TASK, taskObject.asObjectable(), taskObject.getDefinition());
         variables.put(ExpressionConstants.VAR_FILE, commandLineScriptExecutor.getOsSpecificFilePath(reportOutputFilePath), String.class);
 
diff --git a/model/report-impl/src/main/java/com/evolveum/midpoint/report/impl/ReportTaskHandler.java b/model/report-impl/src/main/java/com/evolveum/midpoint/report/impl/ReportTaskHandler.java
index 00ea94ca92e..d940c9dd57b 100644
--- a/model/report-impl/src/main/java/com/evolveum/midpoint/report/impl/ReportTaskHandler.java
+++ b/model/report-impl/src/main/java/com/evolveum/midpoint/report/impl/ReportTaskHandler.java
@@ -265,7 +265,7 @@ private void processPostReportScript(ReportType parentReport, String reportOutpu
 
         VariablesMap variables = new VariablesMap();
         variables.put(ExpressionConstants.VAR_OBJECT, parentReport, parentReport.asPrismObject().getDefinition());
-        PrismObject<TaskType> taskObject = task.getUpdatedOrClonedTaskObject();
+        PrismObject<TaskType> taskObject = task.getRawTaskObjectClonedIfNecessary();
         variables.put(ExpressionConstants.VAR_TASK, taskObject.asObjectable(), taskObject.getDefinition());
         variables.put(ExpressionConstants.VAR_FILE, reportService.getCommandLineScriptExecutor().getOsSpecificFilePath(reportOutputFilePath), String.class);
 
diff --git a/repo/task-api/src/main/java/com/evolveum/midpoint/task/api/Task.java b/repo/task-api/src/main/java/com/evolveum/midpoint/task/api/Task.java
index 15ebd8f088e..62380a9a4a6 100644
--- a/repo/task-api/src/main/java/com/evolveum/midpoint/task/api/Task.java
+++ b/repo/task-api/src/main/java/com/evolveum/midpoint/task/api/Task.java
@@ -717,30 +717,25 @@ default List<? extends Task> listSubtasks(OperationResult parentResult) throws S
     //region Task object as a whole
 
     /**
-     * Returns backing task prism object.
-     *
-     * *AVOID* use of this method if possible:
-     *
-     * - for regular tasks it has to update operation result in the prism object (might be costly)
-     * - for running tasks it provides a clone of the actual prism object (even more costly and leads to lost changes
-     *   if the returned value is changed)
+     * Returns backing task prism object without updating with current operation result.
+     * If the task is running, a clone is returned.
      */
     @NotNull
-    PrismObject<TaskType> getUpdatedOrClonedTaskObject();
+    PrismObject<TaskType> getRawTaskObjectClonedIfNecessary();
 
     /**
-     * Returns backing task prism object, provided that task is not running.
-     * Beware that the task operation result is updated (might be costly).
-     * @throws IllegalStateException if task is running
+     * Returns CLONE of backing task prism object without updating with current operation result.
      */
     @NotNull
-    PrismObject<TaskType> getUpdatedTaskObject();
+    PrismObject<TaskType> getRawTaskObjectClone();
 
     /**
-     * Returns cloned task object.
+     * Returns backing task prism object UPDATED with current operation result.
+     *
+     * Assumes that task is not running. (Otherwise IllegalStateException is thrown.)
      */
     @NotNull
-    PrismObject<TaskType> getClonedTaskObject();
+    PrismObject<TaskType> getUpdatedTaskObject();
 
     /**
      * Returns a reference to the task prism.
diff --git a/repo/task-api/src/main/java/com/evolveum/midpoint/task/api/test/NullTaskImpl.java b/repo/task-api/src/main/java/com/evolveum/midpoint/task/api/test/NullTaskImpl.java
index 847c9b2799d..8939f40b2e1 100644
--- a/repo/task-api/src/main/java/com/evolveum/midpoint/task/api/test/NullTaskImpl.java
+++ b/repo/task-api/src/main/java/com/evolveum/midpoint/task/api/test/NullTaskImpl.java
@@ -317,21 +317,14 @@ public void setProgressImmediate(Long progress, OperationResult parentResult) {
         throw new UnsupportedOperationException();
     }
 
-    @NotNull
-    @Override
-    public PrismObject<TaskType> getUpdatedOrClonedTaskObject() {
-        throw new UnsupportedOperationException();
-    }
-
     @NotNull
     @Override
     public PrismObject<TaskType> getUpdatedTaskObject() {
         throw new UnsupportedOperationException();
     }
 
-    @NotNull
     @Override
-    public PrismObject<TaskType> getClonedTaskObject() {
+    public @NotNull PrismObject<TaskType> getRawTaskObjectClone() {
         throw new UnsupportedOperationException();
     }
 
@@ -492,6 +485,11 @@ public List<Task> listPrerequisiteTasks(OperationResult parentResult) {
         throw new UnsupportedOperationException();
     }
 
+    @Override
+    public @NotNull PrismObject<TaskType> getRawTaskObjectClonedIfNecessary() {
+        throw new UnsupportedOperationException();
+    }
+
     @Override
     public List<String> getDependents() {
         throw new UnsupportedOperationException();
diff --git a/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/LightweightTaskManager.java b/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/LightweightTaskManager.java
index 4473c401ce5..a2398d0236f 100644
--- a/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/LightweightTaskManager.java
+++ b/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/LightweightTaskManager.java
@@ -48,7 +48,7 @@ public Collection<TaskQuartzImpl> getTransientSubtasks(String identifier) {
         if (runningInstance != null) {
             List<TaskQuartzImpl> subtasks = new ArrayList<>();
             for (RunningTaskQuartzImpl subtask : runningInstance.getLightweightAsynchronousSubtasks()) {
-                subtasks.add(subtask.cloneAsStaticTask());
+                subtasks.add(subtask.cloneAsStaticTask()); // Beware, does not update operation result in task prism
             }
             return subtasks;
         } else {
diff --git a/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/TaskQuartzImpl.java b/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/TaskQuartzImpl.java
index 7116f96c00b..04aa2df4128 100644
--- a/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/TaskQuartzImpl.java
+++ b/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/TaskQuartzImpl.java
@@ -272,30 +272,32 @@ private boolean isLiveRunningInstance() {
         return this instanceof RunningTask;
     }
 
-    /**
-     * TODO TODO TODO (think out better name)
-     * Use with care. Never provide to outside world (beyond task manager).
-     */
-    public PrismObject<TaskType> getLiveTaskObjectForNotRunningTasks() {
+    @NotNull
+    @Override
+    public PrismObject<TaskType> getRawTaskObjectClonedIfNecessary() {
         if (isLiveRunningInstance()) {
-            throw new UnsupportedOperationException("It is not possible to get live task prism object from the running task instance: " + this);
+            return getRawTaskObjectClone();
         } else {
             return taskPrism;
         }
     }
 
-    // Use with utmost care! Never provide to outside world (beyond task manager)
-    public PrismObject<TaskType> getLiveTaskObject() {
-        return taskPrism;
-    }
-
     @NotNull
     @Override
-    public PrismObject<TaskType> getUpdatedOrClonedTaskObject() {
+    public PrismObject<TaskType> getRawTaskObjectClone() {
+        synchronized (prismAccess) {
+            return taskPrism.clone();
+        }
+    }
+
+
+    /**
+     * Returns the backing task prism object. Not supported for running task instances.
+     */
+    public PrismObject<TaskType> getRawTaskObject() {
         if (isLiveRunningInstance()) {
-            return getClonedTaskObject();
+            throw new IllegalStateException("Cannot get task object from live running task instance");
         } else {
-            updateTaskPrismResult(taskPrism);
             return taskPrism;
         }
     }
@@ -312,17 +314,7 @@ public PrismObject<TaskType> getUpdatedTaskObject() {
     }
 
     TaskQuartzImpl cloneAsStaticTask() {
-        return TaskQuartzImpl.createFromPrismObject(taskManager, getClonedTaskObject());
-    }
-
-    @NotNull
-    @Override
-    public PrismObject<TaskType> getClonedTaskObject() {
-        synchronized (prismAccess) {
-            PrismObject<TaskType> rv = taskPrism.clone();
-            updateTaskPrismResult(rv);
-            return rv;
-        }
+        return TaskQuartzImpl.createFromPrismObject(taskManager, getRawTaskObjectClone());
     }
 
     public boolean isRecreateQuartzTrigger() {
diff --git a/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/tasks/TaskPersister.java b/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/tasks/TaskPersister.java
index c0239a45be8..efceee81f78 100644
--- a/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/tasks/TaskPersister.java
+++ b/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/tasks/TaskPersister.java
@@ -96,7 +96,7 @@ private void persist(TaskQuartzImpl task, OperationResult result) {
         }
 
         try {
-            CryptoUtil.encryptValues(protector, task.getLiveTaskObjectForNotRunningTasks());
+            CryptoUtil.encryptValues(protector, task.getRawTaskObject());
             addTaskToRepositoryAndQuartz(task, null, result);
         } catch (ObjectAlreadyExistsException ex) {
             // This should not happen. If it does, it is a bug. It is OK to convert to a runtime exception
diff --git a/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/tasks/TaskRetriever.java b/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/tasks/TaskRetriever.java
index bbd40614ce4..ea33bc683c1 100644
--- a/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/tasks/TaskRetriever.java
+++ b/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/tasks/TaskRetriever.java
@@ -223,7 +223,7 @@ private List<?> getSubtasks(Object task, OperationResult result) throws SchemaEx
     private void addSubtask(Object task, Object subtask) {
         TaskType subtaskBean;
         if (subtask instanceof TaskQuartzImpl) {
-            subtaskBean = ((TaskQuartzImpl) subtask).getLiveTaskObject().asObjectable();
+            subtaskBean = ((TaskQuartzImpl) subtask).getRawTaskObjectClonedIfNecessary().asObjectable();
         } else if (subtask instanceof PrismObject<?>) {
             //noinspection unchecked
             subtaskBean = ((PrismObject<TaskType>) subtask).asObjectable();
@@ -336,7 +336,7 @@ private void addTransientTaskInformation(Object task, ClusterStatusInformation c
         }
         TaskType taskBean;
         if (task instanceof TaskQuartzImpl) {
-            taskBean = ((TaskQuartzImpl) task).getLiveTaskObjectForNotRunningTasks().asObjectable();
+            taskBean = ((TaskQuartzImpl) task).getRawTaskObject().asObjectable();
         } else if (task instanceof PrismObject<?>) {
             //noinspection unchecked
             taskBean = ((PrismObject<TaskType>) task).asObjectable();
diff --git a/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/tracing/TracingOutputCreator.java b/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/tracing/TracingOutputCreator.java
index 350a97e002c..8f92be7a121 100644
--- a/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/tracing/TracingOutputCreator.java
+++ b/repo/task-quartz-impl/src/main/java/com/evolveum/midpoint/task/quartzimpl/tracing/TracingOutputCreator.java
@@ -86,7 +86,7 @@ private TracingEnvironmentType createTracingEnvironmentDescription(Task task, Tr
             selectedNodeInformation.setClustered(localNode.isClustered());
             environment.setNodeRef(ObjectTypeUtil.createObjectRefWithFullObject(selectedNodeInformation, prismContext));
         }
-        TaskType taskClone = task.getClonedTaskObject().asObjectable();
+        TaskType taskClone = task.getRawTaskObjectClone().asObjectable(); // is it OK that we use not updated op. result?
         if (taskClone.getResult() != null) {
             taskClone.getResult().getPartialResults().clear();
         }
diff --git a/repo/task-quartz-impl/src/test/java/com/evolveum/midpoint/task/quartzimpl/MockParallelTaskHandler.java b/repo/task-quartz-impl/src/test/java/com/evolveum/midpoint/task/quartzimpl/MockParallelTaskHandler.java
index 5cf3c0a2976..08182287f71 100644
--- a/repo/task-quartz-impl/src/test/java/com/evolveum/midpoint/task/quartzimpl/MockParallelTaskHandler.java
+++ b/repo/task-quartz-impl/src/test/java/com/evolveum/midpoint/task/quartzimpl/MockParallelTaskHandler.java
@@ -54,7 +54,7 @@ public static class MyLightweightTaskHandler implements LightweightTaskHandler {
         private boolean hasRun = false;
         private boolean hasExited = false;
         private final long duration;
-        private static final long STEP = 100;
+        private static final long STEP = 10;
 
         MyLightweightTaskHandler(Integer duration) {
             this.duration = duration != null ? duration : 86400L * 1000L * 365000L; // 1000 years
@@ -72,8 +72,9 @@ public void run(RunningLightweightTask task) {
             //assertTrue("Subtask is not in Running LAT list of parent", isAmongRunningChildren(task, parentTask));
 
             while (System.currentTimeMillis() < end && task.canRun()) {
-                // hoping to get ConcurrentModificationException when setting operation result here (MID-5113)
-                task.getLightweightTaskParent().getUpdatedOrClonedTaskObject();
+                // Check for some concurrency issues - although not related to the operation result, because
+                // it is inherently not thread-safe.
+                task.getLightweightTaskParent().getRawTaskObjectClonedIfNecessary();
                 IterationItemInformation info = new IterationItemInformation("o1", null, UserType.COMPLEX_TYPE, "oid1");
                 Operation op = task.recordIterativeOperationStart(info);
                 try {
@@ -88,6 +89,9 @@ public void run(RunningLightweightTask task) {
                     op.failed(e);
                     break;
                 }
+                OperationResult result = task.getResult();
+                result.createSubresult("test");
+                result.summarize();
             }
             hasExited = true;
         }
diff --git a/repo/task-quartz-impl/src/test/java/com/evolveum/midpoint/task/quartzimpl/TestTaskManagerBasic.java b/repo/task-quartz-impl/src/test/java/com/evolveum/midpoint/task/quartzimpl/TestTaskManagerBasic.java
index b3f4b925689..c30ac30a6bd 100644
--- a/repo/task-quartz-impl/src/test/java/com/evolveum/midpoint/task/quartzimpl/TestTaskManagerBasic.java
+++ b/repo/task-quartz-impl/src/test/java/com/evolveum/midpoint/task/quartzimpl/TestTaskManagerBasic.java
@@ -27,6 +27,8 @@
 import com.evolveum.midpoint.schema.util.task.TaskTreeUtil;
 import com.evolveum.midpoint.task.api.RunningLightweightTask;
 
+import com.evolveum.midpoint.util.exception.CommonException;
+
 import org.jetbrains.annotations.NotNull;
 import org.quartz.JobExecutionContext;
 import org.quartz.JobKey;
@@ -52,7 +54,6 @@
 import com.evolveum.midpoint.schema.constants.SchemaConstants;
 import com.evolveum.midpoint.schema.result.OperationResult;
 import com.evolveum.midpoint.schema.result.OperationResultStatus;
-import com.evolveum.midpoint.task.api.RunningTask;
 import com.evolveum.midpoint.task.api.Task;
 import com.evolveum.midpoint.task.api.TaskConstants;
 import com.evolveum.midpoint.task.quartzimpl.cluster.ClusterManager;
@@ -769,6 +770,9 @@ public void test250TaskWithThreads() throws Exception {
         when();
 
         add(TASK_WITH_THREADS, result);
+
+        checkTreadSafety(TASK_WITH_THREADS.oid, 1000L, result);
+
         waitUntilDone(TASK_WITH_THREADS.oid, result, 15000, 100);
         waitForTaskClose(TASK_WITH_THREADS.oid, result, 15000, 100);
 
@@ -787,6 +791,40 @@ public void test250TaskWithThreads() throws Exception {
         }
     }
 
+    /**
+     * A simple test for MID-6910.
+     */
+    @SuppressWarnings("SameParameterValue")
+    private void checkTreadSafety(String oid, long duration, OperationResult result)
+            throws CommonException, InterruptedException {
+
+        PrismObject<TaskType> retrievedTask;
+        long start = System.currentTimeMillis();
+        for (;;) {
+            Collection<SelectorOptions<GetOperationOptions>> options = schemaService.getOperationOptionsBuilder()
+                    .item(TaskType.F_SUBTASK_REF).retrieve()
+                    .build();
+            retrievedTask = taskManager.getObject(TaskType.class, oid, options, result);
+            if (!retrievedTask.asObjectable().getSubtaskRef().isEmpty()) {
+                break;
+            }
+            if (System.currentTimeMillis() - start > 3000) {
+                throw new AssertionError("Timed out waiting for the task to create subtasks");
+            }
+            //noinspection BusyWait
+            Thread.sleep(200);
+        }
+
+        display("Subtasks: " + retrievedTask.asObjectable().getSubtaskRef().size());
+        long startCloning = System.currentTimeMillis();
+        int cloneIterations = 0;
+        while (System.currentTimeMillis() - startCloning < duration) {
+            retrievedTask.clone();
+            cloneIterations++;
+        }
+        display("Clone iterations done: " + cloneIterations);
+    }
+
     @SuppressWarnings("SameParameterValue")
     private void waitUntilDone(String taskOid, OperationResult result, int duration, int checkInterval)
             throws SchemaException, ObjectNotFoundException, InterruptedException {