Question

Commons-logging+jUnit - Bizzarre problem - may be JVM bug?

Asked by: swift99

This is really odd.

I have some jUnit test cases.  When i run them under the JBuilder TestRunner and the text TestRunner, everything is fine.  When I run them under the Swing TestRunner, they blow up because the logger interface casting check fails.

We are using the common-logging interface and log4j.

The exact method that is failing is org.apache.commons.logging.impl.LogFactoryImpl.getLogConstructor().

The exact point of failure is this snip:

            if (!Log.class.isAssignableFrom(logClass)) {
                throw new LogConfigurationException
                    ("Class " + logClassName + " does not implement Log");
            }

logClass is org.apache.commons.logging.impl.Log4JLogger.

I have confirmed both by code review and by visually checking the instance in the debugger (during a cycle where the test fails) that logClass implements the org.apache.commons.logging.Log interface.

I have confirmed that I am using exactly the same class path for all three test runners.

I have ensured that I only have one version of Log4J and commons-logging on my box.

I get the same results with JRE 1.4.1, and 1.4.2.

This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.

Subscribe now for full access to Experts Exchange and get

Instant Access to this Solution

  • Plus...
  • 30 Day FREE access, no risk, no obligation
  • Collaborate with the world's top tech experts
  • Unlimited access to our exclusive solution database
  • Never be left without tech help again

Subscribe Now

Asked On
2004-04-19 at 10:28:56ID20959373
Tags

junit

,

logging

,

commons

Topic

Java Programming Language

Participating Experts
2
Points
250
Comments
21

Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.

  • "The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
  • "Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
  • "Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.

See what Experts Exchange can do for you.

Got a question?

We've got the answer.

Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.

Screenshot of Experts Exchange Knowledgebase

Need individual assistance?

Our experts are ready to help.

If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.

Screenshot of Experts Exchange Knowledgebase

Want to learn from the best?

Read articles from industry experts.

Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.

Screenshot of an Article

Working on a long term project?

Store your work and research.

Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.

Screenshot of Experts Exchange Knowledgebase

Access the answers to your technology questions today.

Subscribe Now

30-day free trial. Register in 60 seconds.

What Makes Experts Exchange Unique?

Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Trusted by the world's most respected brands.

image of each brand's logo

Faithfully serving IT professionals since 1996.

Experts Exchange Logo

Try it out and discover for yourself.

Subscribe Now

30-day free trial. Register in 60 seconds.

Related Solutions

  1. Difference between JVM and JRE?
    Hello All Can anyone tell me the difference between Java Virtual Machine(JVM) and Java Runtime Environment(JRE) Thanks munira
  2. Understanding JRE
    Hi All, Cud u please help me understand this pls. As I understand to run a HelloWorld application program which prints HelloWorld on Console, I need JRE (WHICH COMES WITH JAVA.EXE) and so I can do java HellWorld and it runs HelloWorld. As in other question, I understand ...

Free Tech Articles

  1. WARNING: 5 Reasons why you should NEVER fix a computer for free.
    It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
  2. SCCM OSD Basic troubleshooting
    SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
  3. Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
    This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
  4. Create a Win7 Gadget
    This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
  5. Outlook continually prompting for username and password
    There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
  6. Backup Exchange 2010 Information Store using Windows Backup
    There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...

Cloud Class Webinars

  1. Avoiding Bugs in Microsoft Access
    Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
  2. Top 10 Best New Features in Visio 2010
    Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
  3. IT Consultant Business Secrets Revealed
    Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
  4. Disaster Recovery and Business Continuity
    Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
  5. Organize Your Visio Diagrams with Containers and Lists
    Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
  6. How to Us Objects, Properties, Events and Methods in Microsoft Access
    Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...

Join the Community

Give a Little. Get a Lot.

Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.

Join the Community

Answers

 

by: CEHJPosted on 2004-04-19 at 10:33:54ID: 10861735

>>they blow up because the logger interface casting check fails

What exactly is the error that shows?

 

by: swift99Posted on 2004-04-19 at 10:38:48ID: 10861766

The exact error is:

org.apache.commons.logging.LogConfigurationException: Class org.apache.commons.logging.impl.Log4JLogger does not implement Log.

I have traced into the commons-logging package and comfirmed that it is executing the snip of code identified in the original message.

 

by: CEHJPosted on 2004-04-19 at 10:41:05ID: 10861791

>>does not implement Log.

Make sure you pass the fully-qualified (inc package) class name into the method

 

by: swift99Posted on 2004-04-19 at 10:45:34ID: 10861832

If this were the problem, then wouldn't the text and JBuilder test runners display the same behavior?

I have confirmed visually that the logClass is <org.apache.commons.logging.impl.Log4JLogger> both when the test succeeds and when it fails.

 

by: CEHJPosted on 2004-04-19 at 10:46:22ID: 10861840

i.e.

if (!Log.class.isAssignableFrom(Class.forName("org.apache.commons.logging.Log"))) {
}

 

by: CEHJPosted on 2004-04-19 at 10:48:22ID: 10861852

>>If this were the problem

Could be down to different class loading behaviour. Give the above a try - it can't do any harm - and we can go from there

 

by: swift99Posted on 2004-04-19 at 10:49:52ID: 10861864

This code is part of the apache commons-logging package.  While modification is technically feasible, it should not be necessary.  This package, and its initialization code, is used without alteration by thousands of java apps around the world.

 

by: CEHJPosted on 2004-04-19 at 10:54:52ID: 10861907

>>This code is part of the apache commons-logging package

Do you mean it's their source!? If so then you need to do


Class classToTest = Class.forName("org.apache.commons.logging.Log");

and then pass it to their code

The trouble is, there are so many logging implementations around, if you are not very careful with packages and f.q. names you can get conflicts.

 

by: CEHJPosted on 2004-04-19 at 11:06:08ID: 10862005

If you pass -verbose

java -verbose YourMainClass

you should see where your classes are being loaded from in each case

 

by: swift99Posted on 2004-04-19 at 11:38:15ID: 10862320

Here's something odd from the verbose printout - see the last three lines.

It appears that two versions of Log are being loaded (!?)

[Loaded org.apache.commons.logging.LogFactory]
[Loaded org.apache.commons.logging.LogConfigurationException]
[Loaded java.io.UnsupportedEncodingException from D:\DevTools\JBuilder9\jdk1.4\jre\lib\rt.jar]
[Loaded java.lang.SecurityException from D:\DevTools\JBuilder9\jdk1.4\jre\lib\rt.jar]
[Loaded org.apache.commons.logging.LogFactory$1]
[Loaded org.apache.commons.logging.LogFactory$3]
[Loaded org.apache.commons.logging.LogFactory$2]
[Loaded org.apache.commons.logging.impl.LogFactoryImpl]
[Loaded org.apache.commons.logging.impl.LogFactoryImpl$1]
[Loaded org.apache.log4j.spi.AppenderAttachable]
[Loaded org.apache.log4j.Category]
[Loaded org.apache.log4j.Logger]
[Loaded org.apache.commons.logging.Log]
[Loaded org.apache.commons.logging.impl.Log4JLogger]
[Loaded org.apache.commons.logging.Log]

 

by: CEHJPosted on 2004-04-19 at 11:41:25ID: 10862345

What about the 'from' bit though?

 

by: swift99Posted on 2004-04-19 at 11:58:15ID: 10862494

Now THAT was   interesting ... Under text TestRunner, the JDK14 logger class is used - not the Log4J class.

I think that explains what is different, but not _why_ it is different.  Thanks for the ammo for more research.

 

by: swift99Posted on 2004-04-19 at 11:59:23ID: 10862501

There was no "from" bit for the logging packages.  What you see is what I got.

 

by: CEHJPosted on 2004-04-19 at 12:04:17ID: 10862548

>>Now THAT was   interesting ...

This is precisely the sort of thing i was talking about. Double check the classpath being used in each case

 

by: swift99Posted on 2004-04-19 at 12:09:13ID: 10862575

The class path is identical.  The batch file was copied and the junit.textui.TestRunner was changed to junit.swingui.TestRunner.

 

by: CEHJPosted on 2004-04-19 at 12:11:27ID: 10862592

>>The class path is identical.  

I thought in one case JBuilder was being used? It constructs its own classpath

 

by: swift99Posted on 2004-04-19 at 12:32:38ID: 10862747

Yes ... it is the ultimate origin of all other classpaths.

 

by: objectsPosted on 2004-04-19 at 16:35:00ID: 10864559

Your problem is probably caused by multiple versions of a library being available to the class loader.

 

by: swift99Posted on 2004-04-20 at 06:59:13ID: 10868911

Well ... we were all on the right track.

The jUnit swing TestRunner, under some circumstances, loads the classes twice.  Turning off the "Reload classes every run" checkbox on the TestRunner resolved the problem.  The existence of this checkbox suggests that others have had this problem.

Thanks!

 

by: CEHJPosted on 2004-04-20 at 07:02:10ID: 10868933

8-)

 

by: objectsPosted on 2004-04-20 at 15:17:30ID: 10873144

20120131-EE-VQP-002

3 Ways to Join

30-Day Free Trial

The Experts

98% positive feedback on 31,087 answers since March 2000. angeliii is a Microsoft Most Valuable Professional for his work with MS SQL Server & Develoment.

He has also proven his knowledge of Visual Basic Programming, PHP Scripting and Oracle Databases.

The Experts

97% positive feedback on 10,752 answers since July 2000. lrmoore has more than 18 years experience in the networking industry.

The six-time Mircosoft MVPs specialties include firewalls, virtual private networking, and network management.

Testimonials

"...and excellent source for support... Kind of like having your very own IT dept." Electriciansnet

Testimonials

"I was apprehensive at signing up at first. However... it has already made my life as an IT administrator much easier." JaCrews

Testimonials

"WOW! You guys have great, active, and knowledgeable people on here." moore50

Business Clients

Business Clients

In the Press

"If you’ve got a question... Experts Exchange can supply an answer.”

In the Press

"...an invaluable aid for both IT professionals and those who require tech support."

In the Press

"where IT professionals provide quick answers on just about any topic"

Business Account Plans

Loading Advertisement...