whats the difference between issueReload and restartSplunkd in serverclass.conf ?

[damode]

As per the docs, issueReload determines whether the client's splunkd reloads after receiving an update and
restartSplunkd determines whether the client's splunkd restarts after receiving an update.

Can somebody please explain what happens internally in Splunk when client reloads vs client restarts ?

[duartet]

From: https://docs.splunk.com/Documentation/Splunk/8.0.6/Admin/Serverclassconf

restartSplunkd = <boolean>
* If true, restarts splunkd on the client when a member app or a directly
  configured app is updated.
* Can be overridden at the serverClass level and the serverClass:app level.
* Default: false

issueReload = <boolean>
* If true, triggers a reload of internal processors at the client when a
  member app or a directly configured app is updated.
* If you don't want to immediately start using an app that is pushed to a
  client, you should set this to false.
* Default: false

Here you have the behavior of combining the options:
https://docs.splunk.com/Documentation/Splunk/8.0.6/Updating/Useserverclass.conf

Interaction of restartSplunkd and issueReload

The behavior of the client varies depending on the settings of restartSplunkd and issueReload. These are the options:

issueReload restartSplunkd Behavior

true	false	Reload only. No restart. It might be necessary to issue a manual restart to fully activate the downloaded apps.
true	true	Client reloads. If some app components require a restart to activate, the client restarts.
false	false	The downloaded apps are not activated.
false	true	The client always restarts after app updates.