eclipse ant build failed Unable to delete file lib\build

Question

When running certain build.xml targets, the clean has a hit or miss on deleting the ivy jar directory. The "locked" files are by eclipse, using explorer on the directory or rerunning ant from eclipse refuses to delete it until restart of eclipse. This is very time consuming. Some reason eclipse is holding on to this files after running ant build/clean.
It's not all the projects and only at certain times for unknown reasons.

There is this existing discussion. Eclipse won't delete files

but it doesn't answer the question for me about how to get eclipse to run ant without having to restart every time.

Is there a way to use eclipse -console to see the file handles what is holding it? or does somebody know a root cause to why eclipse/ant/ivy wont let go of these targets after a build or two (1st time after a fresh start of Eclipse works fine) but then some subsequent ant build after that it becomes unhappy.

In my case it is eclipse which is locking the file for sure. Restarting Eclipse is not a solution. Otherwise, I'll just go back to a command line window. I've tried setting the run in same jvm, and all sorts of settings.

Do I need to debug the eclipse plugins? Is there an easier way to find out what's not release the lock within Eclipse and it's plugins? This is my first time ever to see this and I suspect it's IVY causing it.

Running juno, ivy, spring, ant and have the problem when run-as Ant Build from Eclipse that clean is unable to delete the lib/build directory of the artifacts.

eclipse.buildId=M20130204-1200
java.version=1.6.0_43
java.vendor=Sun Microsystems Inc.
BootLoader constants: OS=win32, ARCH=x86, WS=win32, NL=en_US
Framework arguments:  -product org.eclipse.epp.package.jee.product
Command-line arguments:  -os win32 -ws win32 -arch x86 -product org.eclipse.epp.package.jee.product

!ENTRY org.apache.ivyde.eclipse 1 0 2013-06-04 11:36:50.344 
!MESSAGE starting IvyDE plugin

ant target:

    <target name="clean-retrieved" >
    <delete includeemptydirs="true" >
            <fileset dir="${basedir}">
                <include name="lib/**" />
            </fileset>
    </delete>
</target>

ERROR:

clean-retrieved:

BUILD FAILED
C:\scripts\common-build-targets.xml:238: Unable to delete file C:\scripts\lib\build\annotations-1.3.8.jar <<just first jar file in directory..

Answer 1

This occurs when a process is using said file. I've had this issue happen usually when the program that uses said jar is still running. Verify that you aren't still running your program in eclipse. The easiest way to see that visually is to see this:

That red square (stop button) being enabled means that your program is still running. If you press that, you'd be stopping your process. However, if your program wasn't running it'd look something like this:

Since the "stop" button isn't enabled, it means the program isn't running. However, it's possible that there are other processes also running, other than the one shown at the time. To see that, you can see a "computer screen" icon on this next screenshot:

That computer screen being enabled signifies that you have ran multiple programs/processes. Clicking on the down arrow lets you change to other programs. Check to see if those are running, and stop those also. An easier way is to press the double X's symbol. That will close every section related to a finished process, and might show you one that is still running, that you can stop. Continue pressing the double x and the stop button until all are gone, and you should be able to delete your jar, and build without issue.

Answer 2

I've started to see this problem with more recent Eclipse updates. It turns out that the ant plugin would lock all the jar files referenced in build files even before the tasks are executed. To disable this strange "feature" I did the following and it made the problem go away:

1. Open menu Window > Preferences > Ant > Editor > Content Assist
2. Disable the option Provide proposals for user defined tasks
3. Restart Eclipse