here's what I did. and changing all the code to use this.
==========================================
private static final String LOCK = "Lock";
public Document getDocument(Map objectModel,String attrname)
throws ParserConfigurationException
{
Request request = ObjectModelHelper.getRequest(objectModel);
Session session = request.getSession(true);
Document doc = (Document)session.getAttribute(attrname);
if (doc == null)
{
// It is possible for more than one thread to get here at
// the same time with doc == null
synchronized(LOCK)
{
// So check again. Only the first caller should
// actually create the
document.
doc = (Document)session.getAttribute(attrname);
if (doc == null)
{
DocumentBuilderFactory dbf =
DocumentBuilderFactory.newInstance();
doc = dbf.newDocumentBuilder().newDocument();
session.setAttribute(attrname, doc);
}
}
}
return doc;
}
=====================================
but why do we need static method?? please guide me
thanks
Kiran Kumar (Raj)
(502) 696-7203
-----Original Message-----
From: Ralph Goers [mailto:[EMAIL PROTECTED]
Sent: Sunday, April 17, 2005 12:27 PM
To: [email protected]
Subject: Re: Problem with sharing sessions/ multithreading
Torsten Curdt wrote:
>
>Don't want to be picky ...but better don't use DCL
>
>http://www.javaworld.com/javaworld/jw-05-2001/jw-0525-double.html
>
>cheers
>
>
Thanks, that article wasn't too helpful in figuring out why the
technique doesn't work. However, it refreences an article from Alan
Holub that does. From his description, the following version of the DCL
should work fine. I'm not sure the function actually has to be static.
From what I could tell synchronized should be sufficient.
Document getDocument()
{
Request request = ObjectModelHelper.getRequest(objectModel);
Session session = request.getSession(true);
Document doc = (Document)session.getAttribute("myAttribute");
if (doc == null)
{
// It is possible for more than one thread to get here at
the same time with doc == null
syncronize(LOCK);
{ // So check again. Only the first caller should
actually create the document.
doc = (Document)session.getAttribute("myAttribute");
if (doc == null)
{
DocumentBuilderFactory dbf =
DocumentBuilderFactory.newInstance();
doc = buildDocument(dbf);
session.setAttribute("myAttribute", doc);
}
}
}
return doc;
}
private static synchronized Document
buildDocument(DocumentBuilderFactory dbf)
{
return dbf.newDocumentBuilder().newDocument();
}
>--
>Torsten
>
>
