[KARAF-6385] WARNING: sun.reflect.Reflection.getCallerClass is not supported. This will impact performance.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 4.3.0, 4.2.7
• Component/s: karaf

Environment

Karaf 4.3.0 + Java 11

• Assignee: Jean-Baptiste Onofré
• Reporter: Xtra Coder
• Created: 22/Aug/19 08:27
• Updated: 06/Sep/19 16:12
• Resolved: 06/Sep/19 16:12

Description

I've tried using Karaf 4.3.0 built from sources (to fix another issue) and on Java 11 now am always getting following message in console: 

WARNING: sun.reflect.Reflection.getCallerClass is not supported. This will impact performance.

It appears it comes from log4j (specifically this line) and is raised because on Java 11 reflection from Java8 does not work and "org.ops4j.pax.logging" does not include java9-compatible classes most probably because of this issue.

This message does not appear in Karaf 4.2.6 and after some debugging I see this is happening because in 4.2.6 version of "org.ops4j.pax.logging" is 1.10.2 and code goes through this line:
getServices() returns null and therefore event.getLocationInformation() is not invoked

    public void doAppend( PaxLoggingEvent event )
    {
        if (count != getTrackingCount()) {
            count = getTrackingCount();
            appenders = getServices();
        }
        if (appenders != null && appenders.length > 0) {
            // Bug in Karaf, as it expects the source to be available
            event.getLocationInformation();
            for (Object appender : appenders) {
                ((PaxAppender) appender).doAppend(event);
            }
        }
    }

In "org.ops4j.pax.logging" v1.11.0 (included in 4.3.0) code goes through this line:
because getServices(<empty array>) returns that same empty array, code falls into 'if' with that empty array and event.getLocationInformation(); is called (what throws the subject WARNING), whereas its output is not used because list of appenders is empty - no event.getLocationInformation() == no WARNING

        @Override
    public void doAppend(PaxLoggingEvent event) {
        if (count != getTrackingCount()) {
            count = getTrackingCount();
            appenders = getServices(new PaxAppender[0]);
        }
        if (appenders != null) {
            // Bug in Karaf, as it expects the source to be available
            event.getLocationInformation();
            for (PaxAppender appender : appenders) {
                appender.doAppend(event);
            }
        }
    }

So ... it seems it is bug in "org.ops4j.pax.logging" v1.11.0 and it is to early to include it into Karaf.

 

Issue Links

• is blocked by: KARAF-6403 Upgrade to Pax Logging 1.11.2