Monday, December 18, 2006

A JRockit Bug

Part of the fun debugging testsuites is discovering JVM Bugs.
This one is from the JRockit jdk5 JVM - to reproduce:


import java.lang.management.*;
import javax.management.*;

/**
* Simple test to demonstrate JRockit Bug on Windows and RHEL (and possibly other platforms)
*
* The problem only appears under JRockit and it is really a JVM bug.
* The same test passes with Sun's JVM.
*
* java version "1.5.0_06"
* Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-b05)
* BEA JRockit(R) (build R26.4.0-63-63688-1.5.0_06-20060626-2259-win-ia32, )
*
* OS/Kernel/Arch = RHEL4/U4 - Linux 2.6.9-42.0.2.ELsmp
* #1 SMP Thu Aug 17 17:57:31 EDT 2006 x86_64 x86_64 x86_64 GNU/Linux
* JVM = R26.4.0-63_CR284516-68626-1.5.0_06-20060926-0859-linux-x86_64
*
* From jmx 1.2 spec, Chapter 2, MBean Instrumentation (pp57):
*
* MBeanAttributeInfo Class
* "The isIs method will return true if this attribute has a boolean type
* and a getter method with the is prefix (versus the get prefix); otherwise
* it will return false. Note that this information is only relevant
* for a standard MBean".
*
* Original Issue
* see http://jira.jboss.com/jira/browse/JBAS-3746
*/
public class TestMBeanAttributeInfo
{
public static void main(String args[]) throws Exception
{
MBeanServer server = ManagementFactory.getPlatformMBeanServer();
ObjectName oname = new ObjectName(":name=mbeanInfoTest");
server.registerMBean(new Simple(), oname);
MBeanInfo info = server.getMBeanInfo(oname);
MBeanAttributeInfo attr = info.getAttributes()[0];
System.out.println(
"Attribute '" + attr.getName() +
"' : type=" + attr.getType() +
", isReadable=" + attr.isReadable() +
", isWriteable=" + attr.isWritable() +
", isIs=" + attr.isIs());

if (attr.isIs() == false)
{
System.err.println("ERROR: MBeanAttributeInfo.isIs() returns false, it should be true");
System.exit(1);
}
}

public static class Simple implements SimpleMBean
{
private boolean someBoolean;

public boolean isSomeBoolean() { return someBoolean; }
public void setSomeBoolean(boolean someBoolean) { this.someBoolean = someBoolean; }
}

public interface SimpleMBean
{
boolean isSomeBoolean();
void setSomeBoolean(boolean someBoolean);
}
}

2 comments:

sla said...

You will be happy to know that we will release an updated JRockit later today which fixes this problem - as well as other improvements!

:-)

Regards,
/Staffan, JRockit Team

Dimitris Andreadis said...

Perfect, thanks!