Batch client allocation updates to the server

client/alloc_runner.go

@@ -30,7 +30,7 @@ const (
 )
 
 // AllocStateUpdater is used to update the status of an allocation
-type AllocStateUpdater func(alloc *structs.Allocation) error
+type AllocStateUpdater func(alloc *structs.Allocation)
 
 // AllocRunner is used to wrap an allocation and provide the execution context.
 type AllocRunner struct {
@@ -262,9 +262,12 @@ func (r *AllocRunner) Alloc() *structs.Allocation {
 		alloc.ClientStatus = structs.AllocClientStatusFailed
 	} else if running {
 		alloc.ClientStatus = structs.AllocClientStatusRunning
-	} else if dead && !pending {
+	} else if pending {
+		alloc.ClientStatus = structs.AllocClientStatusPending
+	} else if dead {
 		alloc.ClientStatus = structs.AllocClientStatusDead
 	}
+
 	return alloc
 }
 
@@ -273,42 +276,19 @@ func (r *AllocRunner) dirtySyncState() {
 	for {
 		select {
 		case <-r.dirtyCh:
-			r.retrySyncState(r.destroyCh)
+			r.syncStatus()
 		case <-r.destroyCh:
 			return
 		}
 	}
 }
 
-// retrySyncState is used to retry the state sync until success
-func (r *AllocRunner) retrySyncState(stopCh chan struct{}) {
-	for {
-		if err := r.syncStatus(); err == nil {
-			// The Alloc State might have been re-computed so we are
-			// snapshoting only the alloc runner
-			r.saveAllocRunnerState()
-			return
-		}
-		select {
-		case <-time.After(allocSyncRetryIntv + randomStagger(allocSyncRetryIntv)):
-		case <-stopCh:
-			return
-		}
-	}
-}
-
 // syncStatus is used to run and sync the status when it changes
 func (r *AllocRunner) syncStatus() error {
-	// Get a copy of our alloc.
+	// Get a copy of our alloc, update status server side and sync to disk
 	alloc := r.Alloc()
-
-	// Attempt to update the status
-	if err := r.updater(alloc); err != nil {
-		r.logger.Printf("[ERR] client: failed to update alloc '%s' status to %s: %s",
-			alloc.ID, alloc.ClientStatus, err)
-		return err
-	}
-	return nil
+	r.updater(alloc)
+	return r.saveAllocRunnerState()
 }
 
 // setStatus is used to update the allocation status
@@ -475,7 +455,7 @@ OUTER:
 	r.taskLock.Unlock()
 
 	// Final state sync
-	r.retrySyncState(nil)
+	r.syncStatus()
 
 	// Block until we should destroy the state of the alloc
 	r.handleDestroy()

client/alloc_runner_test.go

@@ -16,13 +16,11 @@ import (
 type MockAllocStateUpdater struct {
 	Count  int
 	Allocs []*structs.Allocation
-	Err    error
 }
 
-func (m *MockAllocStateUpdater) Update(alloc *structs.Allocation) error {
+func (m *MockAllocStateUpdater) Update(alloc *structs.Allocation) {
 	m.Count += 1
 	m.Allocs = append(m.Allocs, alloc)
-	return m.Err
 }
 
 func testAllocRunner(restarts bool) (*MockAllocStateUpdater, *AllocRunner) {

client/client.go

@@ -58,6 +58,10 @@ const (
 	// nodeUpdateRetryIntv is how often the client checks for updates to the
 	// node attributes or meta map.
 	nodeUpdateRetryIntv = 5 * time.Second
+
+	// allocSyncIntv is the batching period of allocation updates before they
+	// are synced with the server.
+	allocSyncIntv = 200 * time.Millisecond
 )
 
 // DefaultConfig returns the default configuration
@@ -100,6 +104,9 @@ type Client struct {
 	allocs    map[string]*AllocRunner
 	allocLock sync.RWMutex
 
+	// allocUpdates stores allocations that need to be synced to the server.
+	allocUpdates chan *structs.Allocation
+
 	shutdown     bool
 	shutdownCh   chan struct{}
 	shutdownLock sync.Mutex
@@ -112,12 +119,13 @@ func NewClient(cfg *config.Config) (*Client, error) {
 
 	// Create the client
 	c := &Client{
-		config:     cfg,
-		start:      time.Now(),
-		connPool:   nomad.NewPool(cfg.LogOutput, clientRPCCache, clientMaxStreams, nil),
-		logger:     logger,
-		allocs:     make(map[string]*AllocRunner),
-		shutdownCh: make(chan struct{}),
+		config:       cfg,
+		start:        time.Now(),
+		connPool:     nomad.NewPool(cfg.LogOutput, clientRPCCache, clientMaxStreams, nil),
+		logger:       logger,
+		allocs:       make(map[string]*AllocRunner),
+		allocUpdates: make(chan *structs.Allocation, 64),
+		shutdownCh:   make(chan struct{}),
 	}
 
 	// Setup the Consul Service
@@ -166,6 +174,9 @@ func NewClient(cfg *config.Config) (*Client, error) {
 	// Begin periodic snapshotting of state.
 	go c.periodicSnapshot()
 
+	// Begin syncing allocations to the server
+	go c.allocSync()
+
 	// Start the client!
 	go c.run()
 
@@ -816,19 +827,57 @@ func (c *Client) updateNodeStatus() error {
 }
 
 // updateAllocStatus is used to update the status of an allocation
-func (c *Client) updateAllocStatus(alloc *structs.Allocation) error {
-	args := structs.AllocUpdateRequest{
-		Alloc:        []*structs.Allocation{alloc},
-		WriteRequest: structs.WriteRequest{Region: c.config.Region},
-	}
-	var resp structs.GenericResponse
-	err := c.RPC("Node.UpdateAlloc", &args, &resp)
-	if err != nil {
-		c.logger.Printf("[ERR] client: failed to update allocation: %v", err)
-		return err
-	}
+func (c *Client) updateAllocStatus(alloc *structs.Allocation) {
+	// Only send the fields that are updatable by the client.
+	stripped := new(structs.Allocation)
+	stripped.ID = alloc.ID
+	stripped.TaskStates = alloc.TaskStates
+	stripped.ClientStatus = alloc.ClientStatus
+	stripped.ClientDescription = alloc.ClientDescription
+	c.allocUpdates <- stripped
+}
 
-	return nil
+// allocSync is a long lived function that batches allocation updates to the
+// server.
+func (c *Client) allocSync() {
+	timeoutTimer := time.NewTimer(allocSyncIntv)
+	timeoutCh := timeoutTimer.C
+	updates := make(map[string]*structs.Allocation)
+	for {
+		select {
+		case <-c.shutdownCh:
+			return
+		case alloc := <-c.allocUpdates:
+			// Batch the allocation updates until the timer triggers.
+			updates[alloc.ID] = alloc
+		case <-timeoutCh:
+			// Reset the timer
+			timeoutTimer.Reset(allocSyncIntv)
+
+			// Fast path if there are no updates
+			if len(updates) == 0 {
+				continue
+			}
+
+			sync := make([]*structs.Allocation, 0, len(updates))
+			for _, alloc := range updates {
+				sync = append(sync, alloc)
+			}
+
+			// Send to server.
+			args := structs.AllocUpdateRequest{
+				Alloc:        sync,
+				WriteRequest: structs.WriteRequest{Region: c.config.Region},
+			}
+
+			var resp structs.GenericResponse
+			if err := c.RPC("Node.UpdateAlloc", &args, &resp); err != nil {
+				c.logger.Printf("[ERR] client: failed to update allocations: %v", err)
+			} else {
+				updates = make(map[string]*structs.Allocation)
+			}
+		}
+	}
 }
 
 // allocUpdates holds the results of receiving updated allocations from the

client/client_test.go

@@ -324,27 +324,27 @@ func TestClient_UpdateAllocStatus(t *testing.T) {
 
 	alloc := mock.Alloc()
 	alloc.NodeID = c1.Node().ID
+	originalStatus := "foo"
+	alloc.ClientStatus = originalStatus
 
 	state := s1.State()
 	state.UpsertAllocs(100, []*structs.Allocation{alloc})
 
-	newAlloc := new(structs.Allocation)
-	*newAlloc = *alloc
-	newAlloc.ClientStatus = structs.AllocClientStatusRunning
-
-	err := c1.updateAllocStatus(newAlloc)
-	if err != nil {
+	testutil.WaitForResult(func() (bool, error) {
+		out, err := state.AllocByID(alloc.ID)
+		if err != nil {
+			return false, err
+		}
+		if out == nil {
+			return false, fmt.Errorf("no such alloc")
+		}
+		if out.ClientStatus == originalStatus {
+			return false, fmt.Errorf("Alloc client status not updated; got %v", out.ClientStatus)
+		}
+		return true, nil
+	}, func(err error) {
 		t.Fatalf("err: %v", err)
-	}
-
-	out, err := state.AllocByID(alloc.ID)
-	if err != nil {
-		t.Fatalf("err: %v", err)
-	}
-
-	if out == nil || out.ClientStatus != structs.AllocClientStatusRunning {
-		t.Fatalf("bad: %#v", out)
-	}
+	})
 }
 
 func TestClient_WatchAllocs(t *testing.T) {