Java 11 Garbage Collection Logging Settings Are Not Correctly Applied on Confluence Start

Issue Summary

The default garbage collection configuration for Confluence running Java 11 is incorrectly applied resulting in unexpected logging formats.

Steps to Reproduce

1. Make a change to setenv.sh with new Java 11 garbage collection logging configuration
2. Start Confluence
3. Check Garbage Collection logging

Expected Results

The new garbage collection configuration is reflected in the logging.

Actual Results

The default garbage collection settings for Java are reflected in the logs

Cause

Java 8 and prior used the -Xloggc: syntax for formatting garbage collection log locations. With the introduction of Java 11, the syntax was moved to -Xlog:gc (note the moved colon). In order to maintain some backwards compatibility, the -Xloggc: syntax was remapped to the default Java 11 configuration. This configuration overrides anything else configured with the new syntax.

Details of this change are briefly mentioned at https://bugs.openjdk.java.net/browse/JDK-8170636

Workaround

Confluence Version 7.11.latest and Earlier

Remove the old Java 8 garbage collection configuration which by default is

CATALINA_OPTS="-Xloggc:$LOGBASEABS/logs/gc-`date +%F_%H-%M-%S`.log -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=5 -XX:GCLogFileSize=2M ${CATALINA_OPTS}"

Add the following in place

CATALINA_OPTS="-Xlog:gc*:file=$LOGBASEABS/logs/gc-%t.log:tags,time,uptime,level:filecount=5,filesize=2M ${CATALINA_OPTS}"

Confluence Version 7.12.0 and Later

Comment out the old Java 8 garbage collection configuration which by default is

CATALINA_OPTS="-Xloggc:$LOGBASEABS/logs/gc-`date +%F_%H-%M-%S`.log -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=5 -XX:GCLogFileSize=2M ${CATALINA_OPTS}"