Rogue instance of older version of my Java app running in background?

Question

Hi,

I'm new to Java (come from C++/.NET background) and am experiencing very strange error. I am developing w/ Eclipse IDE on Windows XP on my local desktop. It seems that for some reason, an older (and of course buggier) instance of my application stays running for some very odd reason which I cannot understand.

Even when I close eclipse, this old version of my application is running in the background. So unless I reboot, when I try to test new version of the code, this 'old, rogue instance' is fighting for the resources that are used (files on a share) with the newer (hopfully less buggy) version of the code.

Has anyone experienced this? Does the JVM cache old versions of your Java application for some reason? What am I missing here? When I reboot my machine, the instance finally dies...

I was ripping my hair out trying to figure out why the new version of my code still had the same old bug until I realized this was happening... shrug

Thanks for any help!

Answer 1

Hello,

Java applications run under "java.exe", so you can look for that in the task list. Sadly, if several Java applications are running at the same time, it's hard to tell which is which.

I'm not terribly familiar with Eclipse, but it seems like Eclipse should tell your old version to terminate when you close Eclipse. The JVM doesn't cache past versions.

Hope this helps.

Answer 2

Could be a bug in Eclipse. Could be some code in your application that's spawning a new process. Impossible to tell from over here.

If you haven't already, check out the jps tool, which is included with the regular JDK. It might make it easier to diagnose the problem.

Answer 3

Do you by chance either run your program multiple times, or have forgotten to close one instance of it prior to re-running it from Eclipse?

One thing, that is not very obvious when using Eclipse, is that it allows to run any number of instances of Java programs simultaneously. When you have the Console view active, you have the option to terminate the latest launch.

To switch the console to a different launch (if there are multiple running) you can select from a list, by pressing the "Display Selected Console" icon, which is the monitor icon to the top-right in the Console view. You can also remove any and all terminated launch console outputs from the Console view, by pressing "Remove All Terminated Launches", if every launch have been terminated it should now display "No consoles to display at this time", otherwise the next-newest running launch will be brought to the top.

If this isn't the problem, and indeed Eclipse have lost track of a launch (which is quite rare, but can happen - especially if you spawn sub processes yourself), you can safely terminate any run-amock java.exe process from the Task Manager, as Eclipse runs wrapped in a Windows executable on the Windows platform.