Heartbeat timeout docs

docs/apache-airflow/core-concepts/tasks.rst

@@ -167,25 +167,25 @@ These can be useful if your code has extra knowledge about its environment and w
 
 .. _concepts:zombies:
 
-Zombie Tasks
-------------
+Task Heartbeat Timeout (Zombie Tasks)
+---------------------------------------
 
 No system runs perfectly, and task instances are expected to die once in a while.
 
-*Zombie tasks* are ``TaskInstances`` stuck in a ``running`` state despite their associated jobs being inactive
-(e.g. their process did not send a recent heartbeat as it got killed, or the machine died). Airflow will find these
-periodically, clean them up, and either fail or retry the task depending on its settings. Tasks can become zombies for
+``TaskInstances`` may get stuck in a ``running`` state despite their associated jobs being inactive
+(e.g. their local task job did not send a recent heartbeat as it got killed, or the machine died). Such tasks are also known as zombie tasks. Airflow will find these
+periodically, clean them up, and either fail or retry the task depending on its settings. The heartbeat of a local task job can timeout for
 many reasons, including:
 
 * The Airflow worker ran out of memory and was OOMKilled.
 * The Airflow worker failed its liveness probe, so the system (for example, Kubernetes) restarted the worker.
 * The system (for example, Kubernetes) scaled down and moved an Airflow worker from one node to another.
 
 
-Reproducing zombie tasks locally
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Reproducing task heartbeat timeouts locally
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-If you'd like to reproduce zombie tasks for development/testing processes, follow the steps below:
+If you'd like to reproduce local task job heartbeat timeouts for development/testing processes, follow the steps below:
 
 1. Set the below environment variables for your local Airflow setup (alternatively you could tweak the corresponding config values in airflow.cfg)
 
@@ -216,7 +216,7 @@ If you'd like to reproduce zombie tasks for development/testing processes, follo
     sleep_dag()
 
 
-Run the above DAG and wait for a while. You should see the task instance becoming a zombie task and then being killed by the scheduler.
+Run the above DAG and wait for a while. You should see the task experience a heartbeat timeout and then get killed by the scheduler.