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Concepts

• Heartbeat Period: 
  • The period after which the Agent sends a heartbeat to Master should no other HTTP operation on behalf of the Master be executed.
  • Default: 10s
• Heartbeat Timeout: 
  • The overall timeout that determines if a connection is considered to be lost permanently.
  • Includes the heartbeat period and the delay after which the Master will send its heartbeat.
  • Default: 60s
• Heartbeat Delay:
  • The delay that the JobScheduler 

Use Case

Kill Tasks in case of Connection Loss

• If the Agent receives no heartbeats from the Master within the double period that has been configured for this connection (default: 10s) 120 seconds then the Agent will 
  • assume the connection to be lost and
  • kill any running tasks that have been requested by that Master.
  • This behavior is intended to prevent simultaneous duplicate execution of tasks by an Agent. 
• If the Master receives no heartbeats from the Agent then within the interval between 50 and 60 seconds then it will 
  • consider the task being lost, e.g. its request for execution of a task not to have been received by the Agent, and will assign the task an error state,
  • try to re-establish the connection to the Agent,
  • repeat the request for task execution if the connection to the Agent can be established.
• In this situation the Agent will 
  • within a configurable grace period
    • continue any running tasks.
    • try to identify duplicate requests for task execution from the Master and drop duplicate requests if the task is running.
  • kill the running tasks if the grace period is exceeded.

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• Heartbeat Period: http_heartbeat_period
  • The period after which the Agent sends a heartbeat to Master should no other HTTP operation on behalf of the Master be executed.
  • Default: 10s
• Heartbeat Timeout: http_heartbeat_timeout
  • The overall timeout that determines if a connection is considered to be lost permanently.
  • Includes the heartbeat period and the delay after which the Master will send its heartbeat.
  • Default: 60s

Example

<?xml version="1.0" encoding="utf-8"?>
<process_class>
    <remote_schedulers>
        <remote_scheduler remote_scheduler="http://127.0.0.2:4445" http_heartbeat_period="10" http_heartbeat_timeout="60"/>
    </remote_schedulers>
</process_class>

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