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From Mark Eggers <its_toas...@yahoo.com>
Subject Re: [OT] Cannot cleanly undeploy a web application
Date Tue, 16 Jul 2013 23:47:37 GMT
On 7/16/2013 4:07 PM, Caldarale, Charles R wrote:
>> From: André Warnier [mailto:aw@ice-sa.com] Subject: Re: [OT] Cannot
>> cleanly undeploy a web application
>
>> What probably happens here, is that one level below the InputStream
>> which holds the filehandle in Java, is some native file object
>> which has the file open. The InputStream object is discarded at tbe
>> Java level, but is only really destroyed at the next GC.
>
> That sounds quite feasible.  The real error is that whoever owned the
> InputStream failed to close it, and simply removed all references to
> it, making it unreachable.  The next GC did the close() as part of
> its cleanup work.  The fix would be to find the InputStream and
> explicitly close it.
>
> - Chuck
>

Folks,

It's unfortunate that I can't include multiple parts into the reply.

Ultimately, it's a programmer error. Reading javadoc is good for what 
ails you.

Andre, exactly right. When I caught this on visualvm, there was an 
InputStream with reference to native code but nothing else.

Yep Chuck, I failed to close the InputStream - mainly because . . .

Mark, thanks for pointing out (gently) to RTFJD. While JarURLConnection 
does not have a close method, JarFile certainly does. As well as I 
should be checking the return value from JarURLConnection.getJarFile . . .

Taking those two thoughts in mind, a more correct (still ugly, but it 
works) method might be:

public ArrayList<String> getResources(String resourcePath,
                                       String ending) {
     Pattern p =
         Pattern.compile("^" + resourcePath + "/.+(" + ending + ")$");
     try {
         JarURLConnection urlCon =
             (JarURLConnection) url.openConnection();
         urlCon.setUseCaches(false);
         JarFile jar = urlCon.getJarFile();
         if (null != jar) {
             Enumeration<JarEntry> je = jar.entries();
             while (je.hasMoreElements()) {
                 String entry = je.nextElement().getName();
                 if (log.isDebugEnabled()) {
                     log.debug("JAR entry: " + entry);
                 }
                 Matcher m = p.matcher(entry);
                 if (m.matches()) {
                     resources.add(entry);
                 }
             }
             jar.close();
         } else {
             if (log.isErrorEnabled()) {
                 log.error("Failed to get JarFile entry");
             }
         }
     } catch (IOException ex) {
         if (log.isErrorEnabled()) {
             log.error("Could not open resource", ex);
         }
     }
     return this.resources;
}

Thanks, I was looking at the wrong javadoc.

. . . . sticking to admin stuff, it's less dangerous
/mde/

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