New Jobs app is back up

The new Jobs application (which uses a database to store jobs instead
of a flat file) is back up and is accessible from the trijug.org page. 
It was up briefly a few months ago but had to be taken down because of
problems with memory leaks on the web server.  

My current theory is that most Java web applications will leak memory
when the application is reloaded but since most webapps don't get
reloaded often the problem is generally not noticed.  The TriJUG
website runs on a widely-shared Resin web server which reloads
applications frequently and, thus, leaks like a sieve.

If you are curious, the source for the jobs application is in
Sourceforge as a project named jugjobs.  I have also collected a number
of links to various experts discussing the problem here:

http://haslups.com/stikiweb/viewPage.do?name=EEPProjectNotes.MemoryLeaks

If you read any of the links on the page you will know exactly what the
problem is and how to avoid it.  If you read TWO of the links you will
not be so sure because, although the authors of the linked discussions
write with great conviction and authority, they don't seem to agree on
the exact nature of the problem or on what is to be done about it.  If
you read ALL of the links you will have no clue whatsoever, except that
there is a strong consensus that Java web servers leak memory when
applications are reloaded.

I've rewritten the Jobs application to avoid the use of the Singleton
pattern which several of the discussions identify as a likely candidate
for preventing application class loaders from being garbage collected
when applications are reloaded.  If the TriJUG site suddenly disappears
because our hosting company has turned us off again that might mean
that that wasn't the right solution. 

Lee H


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