From 0f782636f1dd6ed6655e4c20c9c89e4a29473af7 Mon Sep 17 00:00:00 2001
From: Prateek Chaudhry <prateek.chaudhry@gmail.com>
Date: Thu, 15 Jun 2023 00:34:35 -0700
Subject: [PATCH] dont consume resources for acs stopped tasks

---
 agent/engine/docker_task_engine.go | 12 ++++++++++++
 agent/engine/task_manager.go       |  1 +
 2 files changed, 13 insertions(+)

diff --git a/agent/engine/docker_task_engine.go b/agent/engine/docker_task_engine.go
index 5f4e86e018a..bd68010365e 100644
--- a/agent/engine/docker_task_engine.go
+++ b/agent/engine/docker_task_engine.go
@@ -392,6 +392,12 @@ func (engine *DockerTaskEngine) monitorQueuedTasks(ctx context.Context) {
 				if err != nil {
 					break
 				}
+				taskDesiredStatus := task.GetDesiredStatus()
+				if taskDesiredStatus.Terminal() {
+					logger.Info("Task desired status STOPPED while waiting for host resources, progressing without consuming resources", logger.Fields{field.TaskARN: task.Arn})
+					engine.returnWaitingTask()
+					continue
+				}
 				taskHostResources := task.ToHostResources()
 				consumed, err := task.engine.hostResourceManager.consume(task.Arn, taskHostResources)
 				if err != nil {
@@ -409,6 +415,12 @@ func (engine *DockerTaskEngine) monitorQueuedTasks(ctx context.Context) {
 	}
 }
 
+// To be called when resources are not to be consumed by host resource manager, just dequeues and returns
+func (engine *DockerTaskEngine) returnWaitingTask() {
+	task, _ := engine.dequeueTask()
+	task.consumedHostResourceEvent <- struct{}{}
+}
+
 func (engine *DockerTaskEngine) failWaitingTask(err error) {
 	task, _ := engine.dequeueTask()
 	logger.Error(fmt.Sprintf("Error consuming resources due to invalid task config : %s", err.Error()), logger.Fields{field.TaskARN: task.Arn})
diff --git a/agent/engine/task_manager.go b/agent/engine/task_manager.go
index 13f7dcc0991..8015c4a23b3 100644
--- a/agent/engine/task_manager.go
+++ b/agent/engine/task_manager.go
@@ -204,6 +204,7 @@ func (mtask *managedTask) overseeTask() {
 	// - Waits until host resource manager succesfully 'consume's task resources and returns
 	// - For tasks which have crossed this stage before (on agent restarts), resources are pre-consumed - returns immediately
 	// - If the task is already stopped (knownStatus is STOPPED), does not attempt to consume resources - returns immediately
+	// - If an ACS StopTask arrives, host resources manager returns immediately. Host resource manager does not consume resources
 	// (resources are later 'release'd on Stopped task emitTaskEvent call)
 	mtask.waitForHostResources()