tasklist: fix deadlocks

* lock correct resources
* unlock list before queueing

Author: neolynx

task/list.go

@@ -70,19 +70,25 @@ func (list *List) consumer() {
 					task.wgTask.Done()
 					list.wg.Done()
 
+					unlocked := false
 					for _, t := range list.tasks {
 						if t.State == IDLE {
 							// check resources
 							blockingTasks := list.usedResources.UsedBy(t.resources)
 							if len(blockingTasks) == 0 {
-								list.usedResources.MarkInUse(task.resources, task)
+								list.usedResources.MarkInUse(t.resources, t)
+								// unlock list since queueing may block
+								list.Unlock()
+								unlocked = true
 								list.queue <- t
 								break
 							}
 						}
 					}
+					if !unlocked {
+						list.Unlock()
+					}
 				}
-				list.Unlock()
 			}()
 
 		case <-list.queueDone:
@@ -187,7 +193,6 @@ func (list *List) GetTaskReturnValueByID(ID int) (*ProcessReturnValue, error) {
 // become available.
 func (list *List) RunTaskInBackground(name string, resources []string, process Process) (Task, *ResourceConflictError) {
 	list.Lock()
-	defer list.Unlock()
 
 	list.idCounter++
 	wgTask := &sync.WaitGroup{}
@@ -204,7 +209,11 @@ func (list *List) RunTaskInBackground(name string, resources []string, process P
 	tasks := list.usedResources.UsedBy(resources)
 	if len(tasks) == 0 {
 		list.usedResources.MarkInUse(task.resources, task)
+		// queueing task might block if channel not ready, unlock list before queueing
+		list.Unlock()
 		list.queue <- task
+	} else {
+		list.Unlock()
 	}
 
 	return *task, nil