[manager/orchestrator/reaper] Clean out the task reaper dirty set at …

…the end of tick()

Signed-off-by: Anshul Pundir <anshul.pundir@docker.com>

manager/orchestrator/taskreaper/task_reaper.go

@@ -184,12 +184,23 @@ func (tr *TaskReaper) tick() {
 	}
 
 	// Check history of dirty tasks for cleanup.
+	// Note: Clean out the dirty set at the end of this tick iteration
+	// in all but one scenarios (documented below).
+	// When tick() finishes, the tasks in the slot were either cleaned up,
+	// or it was skipped because it didn't meet the criteria for cleaning.
+	// Either way, we can discard the dirty set because future events on
+	// that slot will cause the task to be readded to the dirty set
+	// at that point.
+	//
+	// The only case when we keep the slot dirty is when there are more
+	// than one running tasks present for a given slot.
+	// In that case, we need to keep the slot dirty to allow it to be
+	// cleaned when tick() is called next and one or more the tasks
+	// in that slot have stopped running.
 	tr.store.View(func(tx store.ReadTx) {
 		for dirty := range tr.dirty {
 			service := store.GetService(tx, dirty.ServiceID)
 			if service == nil {
-				// If the service can't be found, assume that it was deleted
-				// and remove the slot from the dirty list.
 				delete(tr.dirty, dirty)
 				continue
 			}
@@ -214,6 +225,7 @@ func (tr *TaskReaper) tick() {
 
 			// Negative value for TaskHistoryRetentionLimit is an indication to never clean up task history.
 			if taskHistory < 0 {
+				delete(tr.dirty, dirty)
 				continue
 			}
 
@@ -243,6 +255,7 @@ func (tr *TaskReaper) tick() {
 			}
 
 			if int64(len(historicTasks)) <= taskHistory {
+				delete(tr.dirty, dirty)
 				continue
 			}
 
@@ -273,6 +286,12 @@ func (tr *TaskReaper) tick() {
 				}
 			}
 
+			// The only case when we keep the slot dirty at the end of tick()
+			// is when there are more than one running tasks present
+			// for a given slot.
+			// In that case, we keep the slot dirty to allow it to be
+			// cleaned when tick() is called next and one or more of
+			// the tasks in that slot have stopped running.
 			if runningTasks <= 1 {
 				delete(tr.dirty, dirty)
 			}

manager/orchestrator/taskreaper/task_reaper_test.go

@@ -2,6 +2,7 @@ package taskreaper
 
 import (
 	"context"
+	"github.com/docker/swarmkit/manager/orchestrator"
 
 	"testing"
 
@@ -805,7 +806,7 @@ func TestServiceRemoveUnassignedTasks(t *testing.T) {
 	}
 
 	// Create a service with one replica specified before the orchestrator is
-	// started. This should result in two tasks when the orchestrator
+	// started. This should result in one tasks when the orchestrator
 	// starts up.
 	err := s.Update(func(tx store.Tx) error {
 		assert.NoError(t, store.CreateService(tx, service1))
@@ -871,3 +872,207 @@ func TestServiceRemoveUnassignedTasks(t *testing.T) {
 	assert.NoError(t, err)
 	assert.Len(t, foundTasks, 1)
 }
+
+func setupTaskReaperDirty(tr *TaskReaper) {
+	tr.dirty[orchestrator.SlotTuple{
+		Slot:      1,
+		ServiceID: "id1",
+		NodeID:    "node1",
+	}] = struct{}{}
+	tr.dirty[orchestrator.SlotTuple{
+		Slot:      1,
+		ServiceID: "id2",
+		NodeID:    "node1",
+	}] = struct{}{}
+}
+
+// TestTick unit-tests the task reaper tick function.
+// 1. Test that the dirty set is cleaned up when the service can't be found.
+// 2. Test that the dirty set is cleaned up when the number of total tasks
+// is smaller than the retention limit.
+// 3. Test that the dirty set and excess tasks in the store are cleaned up
+// when there the number of total tasks is greater than the retention limit.
+func TestTick(t *testing.T) {
+	s := store.NewMemoryStore(nil)
+	assert.NotNil(t, s)
+	defer s.Close()
+
+	assert.NoError(t, s.Update(func(tx store.Tx) error {
+		store.CreateCluster(tx, &api.Cluster{
+			ID: identity.NewID(),
+			Spec: api.ClusterSpec{
+				Annotations: api.Annotations{
+					Name: store.DefaultClusterName,
+				},
+				Orchestration: api.OrchestrationConfig{
+					// set TaskHistoryRetentionLimit to a negative value, so
+					// that tasks are cleaned up right away.
+					TaskHistoryRetentionLimit: 1,
+				},
+			},
+		})
+		return nil
+	}))
+
+	// create the task reaper.
+	taskReaper := New(s)
+
+	// Test # 1
+	// Setup the dirty set with entries to
+	// verify that the dirty set it cleaned up
+	// when the service is not found.
+	setupTaskReaperDirty(taskReaper)
+	// call tick directly and verify dirty set was cleaned up.
+	taskReaper.tick()
+	assert.Zero(t, len(taskReaper.dirty))
+
+	// Test # 2
+	// Verify that the dirty set it cleaned up
+	// when the history limit is set to zero.
+
+	// Create a service in the store for the following test cases.
+	service1 := &api.Service{
+		ID: "id1",
+		Spec: api.ServiceSpec{
+			Annotations: api.Annotations{
+				Name: "name1",
+			},
+			Mode: &api.ServiceSpec_Replicated{
+				Replicated: &api.ReplicatedService{
+					Replicas: 1,
+				},
+			},
+			Task: api.TaskSpec{
+				Restart: &api.RestartPolicy{
+					// Turn off restart to get an accurate count on tasks.
+					Condition: api.RestartOnNone,
+					Delay:     gogotypes.DurationProto(0),
+				},
+			},
+		},
+	}
+
+	// Create another service in the store for the following test cases.
+	service2 := &api.Service{
+		ID: "id2",
+		Spec: api.ServiceSpec{
+			Annotations: api.Annotations{
+				Name: "name2",
+			},
+			Mode: &api.ServiceSpec_Replicated{
+				Replicated: &api.ReplicatedService{
+					Replicas: 1,
+				},
+			},
+			Task: api.TaskSpec{
+				Restart: &api.RestartPolicy{
+					// Turn off restart to get an accurate count on tasks.
+					Condition: api.RestartOnNone,
+					Delay:     gogotypes.DurationProto(0),
+				},
+			},
+		},
+	}
+
+	// Create a service.
+	err := s.Update(func(tx store.Tx) error {
+		assert.NoError(t, store.CreateService(tx, service1))
+		assert.NoError(t, store.CreateService(tx, service2))
+		return nil
+	})
+	assert.NoError(t, err)
+
+	// Setup the dirty set with entries to
+	// verify that the dirty set it cleaned up
+	// when the history limit is set to zero.
+	setupTaskReaperDirty(taskReaper)
+	taskReaper.taskHistory = 0
+	// call tick directly and verify dirty set was cleaned up.
+	taskReaper.tick()
+	assert.Zero(t, len(taskReaper.dirty))
+
+	// Test # 3
+	// Test that the tasks are cleanup when the total number of tasks
+	// is greater than the retention limit.
+
+	// Create tasks for both services in the store.
+	task1 := &api.Task{
+		ID:           "id1task1",
+		Slot:         1,
+		DesiredState: api.TaskStateShutdown,
+		Status: api.TaskStatus{
+			State: api.TaskStateShutdown,
+		},
+		ServiceID: "id1",
+		ServiceAnnotations: api.Annotations{
+			Name: "name1",
+		},
+	}
+
+	task2 := &api.Task{
+		ID:           "id2task1",
+		Slot:         1,
+		DesiredState: api.TaskStateShutdown,
+		Status: api.TaskStatus{
+			State: api.TaskStateShutdown,
+		},
+		ServiceID: "id2",
+		ServiceAnnotations: api.Annotations{
+			Name: "name2",
+		},
+	}
+
+	// Create Tasks.
+	err = s.Update(func(tx store.Tx) error {
+		assert.NoError(t, store.CreateTask(tx, task1))
+		assert.NoError(t, store.CreateTask(tx, task2))
+		return nil
+	})
+	assert.NoError(t, err)
+
+	// Set history to 1 to ensure that the tasks are not cleaned up yet.
+	// At the same time, we should be able to test that the dirty set was
+	// cleaned up at the end of tick().
+	taskReaper.taskHistory = 1
+	setupTaskReaperDirty(taskReaper)
+	// call tick directly and verify dirty set was cleaned up.
+	taskReaper.tick()
+	assert.Zero(t, len(taskReaper.dirty))
+
+	// Now test that tick() function cleans up the old tasks from the store.
+
+	// Create new tasks in the store for the same slots to simulate service update.
+	task1.Status.State = api.TaskStateNew
+	task1.DesiredState = api.TaskStateRunning
+	task1.ID = "id1task2"
+	task2.Status.State = api.TaskStateNew
+	task2.DesiredState = api.TaskStateRunning
+	task2.ID = "id2task2"
+	err = s.Update(func(tx store.Tx) error {
+		assert.NoError(t, store.CreateTask(tx, task1))
+		assert.NoError(t, store.CreateTask(tx, task2))
+		return nil
+	})
+	assert.NoError(t, err)
+
+	watch, cancel := state.Watch(s.WatchQueue() /*api.EventCreateTask{}, api.EventUpdateTask{}*/)
+	defer cancel()
+
+	// Setup the task reaper dirty set.
+	setupTaskReaperDirty(taskReaper)
+	// CVall tick directly and verify dirty set was cleaned up.
+	taskReaper.tick()
+	assert.Zero(t, len(taskReaper.dirty))
+	// Task reaper should delete the task previously marked for SHUTDOWN.
+	deletedTask1 := testutils.WatchTaskDelete(t, watch)
+	assert.Equal(t, api.TaskStateShutdown, deletedTask1.Status.State)
+	assert.Equal(t, api.TaskStateShutdown, deletedTask1.DesiredState)
+	assert.True(t, deletedTask1.ServiceAnnotations.Name == "name1" ||
+		deletedTask1.ServiceAnnotations.Name == "name2")
+
+	deletedTask2 := testutils.WatchTaskDelete(t, watch)
+	assert.Equal(t, api.TaskStateShutdown, deletedTask2.Status.State)
+	assert.Equal(t, api.TaskStateShutdown, deletedTask2.DesiredState)
+	assert.True(t, deletedTask1.ServiceAnnotations.Name == "name1" ||
+		deletedTask1.ServiceAnnotations.Name == "name2")
+}