fix bug

server/workerManager.go

@@ -218,6 +218,7 @@ func (wm *WorkerManager) manageWorker(worker *Worker) error {
 					// add task to cache.
 					worker.recentTask.Add(task.TaskId, task)
 				}
+				log.WithField("worker", worker.uuid).Info("dispatch task to worker")
 
 				select {
 				case dtask.errCh <- err:
@@ -262,6 +263,7 @@ func (wm *WorkerManager) manageWorker(worker *Worker) error {
 					// remove task from cache.
 					worker.recentTask.Remove(result.TaskId)
 				}
+				_ = wm.AddWorker(worker)
 				// todo: post event for task succeed or failed
 				return true
 			}