Hi guys,
What object were you synchronizing on? If the parser is static, for
example, or shared in some other way synchronizing the method won't help.
"synchronized( parser ) {...}" is the best way to go but it needs to go
around every use of the parser, not just in that function.
If that doesn't work then it's possible to get a ConcurrentMod even in a
single thread if the iterator usage is buggy...it could be worth trying a
newer version of Xerces.
--Scott
----- Original Message -----
From: "Scott Stirling" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, May 07, 2002 11:45 AM
Subject: RE: Help with ConcurrentModificationException!
> Hi png,
>
> Does the exception occur when only one client request at a time is sent
> into the method? If so, then digging deeper seems warranted. But if
> you experience this exception while multiple clients are concurrently
> accessing the Servlet that calls the method, then no further explanation
> seems necessary.
>
> Anyway, someone else might have a better suggestion. I was thinking
> maybe the whole method should be synchronized too. I'm going to
> download the Xerces-J source anyway, so I'll check out the class that
> throws the exception.
>
> Scott Stirling
>
> > -----Original Message-----
> > From: png [mailto:[EMAIL PROTECTED]
> > Sent: Tuesday, May 07, 2002 2:34 PM
> > To: '[EMAIL PROTECTED]'
> > Subject: RE: Help with ConcurrentModificationException!
> >
> >
> > Hi, thanks for your suggestion, but in one my revisions of
> > the code i had synchronized the parse.parse call... i'm
> > understand that SAXParsers are not re-entrant, but i'm not
> > sure how it applies in this situation where i make a call to
> > it from another object... or maybe i'm just missing it
> > completely... any more suggestions would be very much appreciated...
> >
> > Thanks!
> >
> > -----Original Message-----
> > From: Scott Stirling [mailto:[EMAIL PROTECTED]
> > Sent: Monday, May 06, 2002 8:28 PM
> > To: [EMAIL PROTECTED]
> > Subject: RE: Help with ConcurrentModificationException!
> >
> >
> > Hi Peter,
> >
> > SAX parsers are not allowed to be re-entrant. Servlets are
> > re-entrant by default unless they implement
> > SingleThreadModel. Try adding a synchronized block around
> > the parser.parse(new XSLTInputSource(is)); call.
> >
> > Best,
> > Scott Stirling
> >
> > > -----Original Message-----
> > > From: png [mailto:[EMAIL PROTECTED]
> > > Sent: Monday, May 06, 2002 6:27 PM
> > > To: '[EMAIL PROTECTED]'
> > > Subject: Help with ConcurrentModificationException!
> > >
> > >
> > > Hey all,
> > >
> > > Please let me know if this is not an appropriate topic for
> > > this mailing list. I apologize if it isn't.
> > >
> > > I get this exception when i'm using the Xerces SAXParser.
> > > I'm using Apache/Resin running Java 1.3.1/Xerces 1.4.4 The
> > > exception is: java.util.ConcurrentModificationException
> > > at
> > > org.apache.xerces.framework.XMLParser.parse(XMLParser.java:1111)
> > > at
> > > com.kargo.comfy.translator.Translator.process(Translator.java:155)
> > > at
> > > com.kargo.comfy.translator.TranslatorServlet.service(Translato
> > > rServlet.java:
> > > 181)
> > > at
> > javax.servlet.http.HttpServlet.service(HttpServlet.java:83)
> > > at
> > > com.caucho.server.http.QNamedDispatcher.service(QNamedDispatch
> > > er.java:153)
> > > at
> > > com.caucho.server.http.QNamedDispatcher.chain(QNamedDispatcher
> > > .java:100)
> > > at
> > > com.caucho.server.http.AbstractRequest.service(AbstractRequest
> > > .java:472)
> > > at
> > > com.caucho.server.http.AbstractRequest.service(AbstractRequest
> > > .java:395)
> > > at
> > > com.caucho.server.http.PageCache$Entry.service(PageCache.java:256)
> > > at
> > > com.caucho.server.http.PageCache.service(PageCache.java:105)
> > > at
> > > com.caucho.server.http.VirtualHost.service(VirtualHost.java:406)
> > > at com.caucho.server.http.Request.dispatch(Request.java:211)
> > > at
> > > com.caucho.server.http.RunnerRequest.handleRequest(RunnerReque
> > > st.java:307)
> > > at
> > > com.caucho.server.http.RunnerRequest.handleConnection(RunnerRe
> > > quest.java:257
> > > )
> > > at
> > com.caucho.server.TcpConnection.run(TcpConnection.java:139)
> > > at java.lang.Thread.run(Thread.java:484)
> > >
> > > The code that calls parse is this. Its within this
> > > Translator class I've
> > > built:
> > > /**
> > > * Sets the states for all filterhandlers using the
> > > * the servlet request and response objects then
> > > * instructs the SAX parser to begin parsing the
> > > * input stream using a stylesheet root for the translation
> > > *
> > > * @param deviceId The id of the device we're talking to
> > > * @param is xml to translate
> > > * @param os stream to send output
> > > * @param ssr compiled stylesheet to use for translation
> > > * @param req HttpServletRequest to be passed to filter handlers
> > > * @param res HttpServletResponse to be passed to
> > filter handlers
> > > * @return void
> > > * @throws org.xml.sax.SAXException, java.io.IOException
> > > */
> > > public void process(InputStream is,
> > > OutputStream os, StylesheetRoot ssr,
> > > HttpServletRequest req,
> > > HttpServletResponse res,
> > > String encoding)
> > > throws SAXException, IOException, Exception
> > > {
> > > setFilterStates(req, res);
> > > processor.setOutputStream(os);
> > > processor.setStylesheet(ssr);
> > > // this won't really work...
> > > processor.setStylesheetParam("encoding",
> > > processor.createXString(encoding));
> > > parser.parse(new XSLTInputSource(is));
> > > reset();
> > > }
> > >
> > > I believe there may be issues with perhaps using the single
> > > parser and processor multiple times and just resetting it.
> > > That is what the reset() method does. "parser" is a Xerces
> > > SAXParser and "processor" is an XSLTProcessor, both as
> > > instance variables. Any suggestions as to why this is
> > > throwing such an exception?
> > >
> > > Thanks!
> > >
> > > peter
> >
> >
> >
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> >
>
>
>
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