Adding Splunk logback appender prevents application termination - logback

Question

I have the following logback configuration and I am using it in a very simple Java application that does nothing except logging one line. When I uncomment the Splunk appender line it doesn't let the application exit, even though the application is finished.
Is there a way to terminate all the logging threads so that the main application exits?
logback.xml
<appender name="SPLUNK" class="com.splunk.logging.HttpEventCollectorLogbackAppender">
<url>${splunkUrl}</url>
<token>${splunkToken}</token>
<source>${projectName}</source>
<host>${COMPUTERNAME}</host>
<sourcetype>batch_application_log:json</sourcetype>
<disableCertificateValidation>true</disableCertificateValidation>
<!--<messageFormat>json</messageFormat>-->
<!--<retries_on_error>1</retries_on_error>-->
<layout class="ch.qos.logback.classic.PatternLayout">
<pattern>"%msg"</pattern>
</layout>
</appender>
<root level="INFO">
<!--<appender-ref ref="SPLUNK"/>--> if I uncomment this line application never exits
</root>
Java code
public class Main {
public static void main(String[] args) {
final Logger logger = LoggerFactory.getLogger(Main.class);
logger.info("******");
}
}

Answer 1

You could add a Logback shutdown hook, this will close all appenders and stop any active threads related to Logback.
For example:
<configuration debug="true">
<shutdownHook class="ch.qos.logback.core.hook.DelayingShutdownHook">
<!--
the default value is 0 millis, I have included a non default
value here just to show you how it can be supplied
-->
<delay>10</delay>
</shutdownHook>
...
<configuration>
With the shutdown hook in place and debug="true" Logback will emit its own log events like so ...
08:57:19,410 |-INFO in ch.qos.logback.core.hook.DelayingShutdownHook#2bafec4c - Sleeping for 10 milliseconds
08:57:19,421 |-INFO in ch.qos.logback.core.hook.DelayingShutdownHook#2bafec4c - Logback context being closed via shutdown hook
Note: there is no requirement to use debug="true", I have only o
included that to show you how to verify that the shutdown hook has been executed.