[Bug 3351] closing jarfile on member of classpath is causing this member to be unusable for all classloaders

[bugzilla-daemon at icedtea.classpath.org]

http://icedtea.classpath.org/bugzilla/show_bug.cgi?id=3351

--- Comment #8 from stefan at kemtrak.com ---
I returned to office this week and I improved the code based on your comments,
thank you very much for the tips and for the nice discussions.
I also saw your more recent comments, really good you managed to reproduce and
locate the issue.
You can see two short comments below if you want.


(In reply to JiriVanek from comment #3)
> (In reply to stefan from comment #2)
> > Hi, I'll break you the good news first, we have the code working!!
> > Still some warnings in the terminal window but it runs at least.
> > See below
> 
> good!
> 
> > 
> > (In reply to JiriVanek from comment #1)
> > > Hi!
> ...
> > 
> > I am just thinking here: If it was Java's JarURLConnection problem, wouldn't
> > that mean that the applet would fail in other implementations as well
> > ?(which it does not).
> 
> Other implementations means proprietary Oracle javaws. HAve you tried on IBM
> javaws? They may even be returning different stream then JarURLConnection.
> This is not safe retyping...
> 
> Last time I was looking into oracle plugin (and so a bit also to javaws)
> there was a lot of copypasted code from Openjdk. With small tweeks. MAybe
> Tehre was also JarURLConnection overwritten.
> That something ITW can not afford.
> 
> 
> > 
> > In any case the code with the localJarFile.close(); commented away is in the
> > usual place and you can see it running now :)
> > 
> > Still some warning messages come up in the console but they are not "fatal"
> > anyway.
> 
> thank you for uplading the app again. As for wornings, I think you can
> ignore happily all  http and bundle related.
> 
> 
> however the java.lang.ClassCastException: java.awt.Frame cannot be cast to
> javax.swing.JFrame is worty of thinking about. This is not first app having
> this problem:
> 
> topFrame =
> ((javax.swing.JFrame)javax.swing.SwingUtilities.getWindowAncestor(this));
> 
> If you can, try to cast it to something more deepr in inheritance. awt.Frame
> should be fine.

Fixed! Thank you very much for catching this!

> 
> > 
> > 
> > > 
> > > In all cases the fix will not be easy.
> > 
> > 
> > Should I leave the code with that line commented away? Is it OK if I do
> > *not* close that connection? I closed the connection after using it because
> > I thought it was good practice. And because Java does not complain, except
> > on the IcedTea case, the code has been running like that for years now.
> > Would it create any problems leaving the connection open? Or it closes when
> > the applet exits?
> 
> Dont forget we are no longer speaking about applet. But about javaws
> application. So having this opened will not harm to much (unlike applet,
> after closgin javaws, its done).
> 
> Anyway - I would recommend you to get rid of those calls at all.
> 
> If you simply call Class.forName on any class from jcalendar, you will
> immediately know if it is correctly downloaded and usable. No need to bother
> with urlstreams.
> Also when you have already have localURL = new java.net.URL("jar", "", cbase
> + "jcalendar.jar!/"); you can simply ocnvert it to File and you will have
> its size.
> 

Just for the sake of the discussion, that would not work. File.length() from
non-local URL/URIs returns 0 size . If the file size is needed, opening an http
or jar connection is recommended, that's why I had to do it like this in the
initial code.
However this is a redundant check (jar file size) and I removed it. I can
always catch the jar-file-not-exists-error by catching the failure of loading a
class from it. I can't be 100% sure that the class does not load because the
jar file is not there (it could be some permission problem) but it is the most
probable reason, so I recoded using that and got rid of the jar connection.
Thanks for the tip anyway!

> 
> 
> Still - note - this may be serious issue in itw. Please fix your application
> so it works on all desired platforms, but dont close this issue. I will
> creeate autoamted reproducer (so you can remove the app you exposed for me) 
> and debug internals of itw...
> 
> happy your app runs fine now. Please get rid of that jarurl connection :)
> 
> 
> 
> 
> 
> 
> > 
> > Thanks!
> 
> np!

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