Hi Oliver,
Thanks for your response.
>Thereforeall your threads have to have their own session
My code doesn't share any session between threads. Only the repository is
shared.
> [...] or you have to synchronize session access to avoid
>the exception you get (which is similar to ConcurrentModificationException
> thrown by standard SDK collections/iterators).
Then a solution (as you suggest) would like something like this :
synchronized( repository ) {
Session session = this.repository.login(new SimpleCredentials("",
"".toCharArray()), null);
//Do something
session.save();
session.logout();
}
What is the preferred approach ?
Also, if I'm responsible for preventing concurrrent sessions, then why is
there those multithreading issues in JIRA :
http://issues.apache.org/jira/browse/JCR-18 &
http://issues.apache.org/jira/browse/JCR-155 ?
Regards,
Nicolas
Le 18:37 2005-07-06, vous avez écrit:
Nicolas,
the JCR spec does not require a session to be thread-safe so you are on
your own to take care for problems like the one you describe. Therefore
all your threads have to have their own session or you have to
synchronize session access to avoid the exception you get (which is
similar to ConcurrentModificationException thrown by standard SDK
collections/iterators).
Oliver
Nicolas Belisle wrote:
> Hi,
>
> I'm a Jackrabbit newbie. I'm doing some tests with the tool and I'm
> having problem with concurrent sessions.
>
> I have joined my (simple) test class (JCRTest) and the exception I get
> from running it.
>
> Anyone had similar problems ?
>
> Regards,
>
> Nicolas
>
>
> -->The exception report:
> java.util.NoSuchElementException: cdeab285-fdbc-4af3-918a-bf4316a29276
> at
> org.apache.jackrabbit.core.LazyItemIterator.next(LazyItemIterator.java:157)
>
> at
>
org.apache.jackrabbit.core.LazyItemIterator.nextNode(LazyItemIterator.java:98)
>
> at app.JCRTest$ThreadDeleter.run(JCRTest.java:107)
>
> -->The class:
> package app;
>
> import java.util.Hashtable;
>
> import javax.jcr.Node;
> import javax.jcr.NodeIterator;
> import javax.jcr.Repository;
> import javax.jcr.RepositoryException;
> import javax.jcr.Session;
> import javax.jcr.SimpleCredentials;
> import javax.jcr.observation.Event;
> import javax.jcr.observation.EventIterator;
> import javax.jcr.observation.EventListener;
> import javax.naming.Context;
> import javax.naming.InitialContext;
>
> import org.apache.jackrabbit.core.jndi.RegistryHelper;
> import org.apache.jackrabbit.core.value.StringValue;
>
> public class JCRTest {
>
> private Repository repository;
>
> public JCRTest(Repository repository) {
> this.repository = repository;
> }
>
> public void execute() throws Exception {
> Session session = this.repository.login(new
> SimpleCredentials("", "".toCharArray()), null);
>
> Node rn = session.getRootNode();
> new ThreadObserver().start();
> Node n = rn.addNode("node" +
> System.currentTimeMillis(), "nt:unstructured");
> n.setProperty("testprop", new StringValue("Hello,
> World."));
> new ThreadDeleter().start();
>
> session.save();
> session.logout();
> }
>
> public static void main(String[] args) {
> try {
> String configFile = "repository/repository.xml";
> String repHomeDir = "repository";
>
> Hashtable env = new Hashtable();
> env.put(Context.INITIAL_CONTEXT_FACTORY,
> "org.apache.jackrabbit.core.jndi.provider.DummyInitialContextFactory");
> env.put(Context.PROVIDER_URL, "localhost");
> InitialContext ctx = new InitialContext(env);
>
> RegistryHelper.registerRepository(ctx, "repo",
> configFile, repHomeDir, true);
> Repository r = (Repository) ctx.lookup("repo");
>
> for (int i = 0; i < 20; i++) {
> JCRTest test = new JCRTest(r);
> test.execute();
> }
>
> } catch (Exception e){
> e.printStackTrace();
> }
> }
>
> public class ThreadObserver extends Thread {
> public void run() {
> System.out.println("Observing thread started");
> try {
> Session session = repository.login(new
> SimpleCredentials("", "".toCharArray()));
> EventListener el = new EventListener() {
> public void
> onEvent(EventIterator events) {
> while
> (events.hasNext()) {
> try {
> Thread.sleep(100);
> } catch (InterruptedException e) {}
>
> Event e = events.nextEvent();
> if
> (e.getType() == Event.NODE_ADDED) {
> try {
>
> System.out.println("Node added : " + e.getPath());
> }
> catch (RepositoryException re) {
>
> re.printStackTrace();
> }
> }
> }
> }
> };
>
> session.getWorkspace().getObservationManager().addEventListener(el,
> Event.NODE_ADDED, "/", true, null, null, false);
> session.save();
> //Some time to listen
> Thread.sleep(500);
> session.logout();
> } catch (Exception e) {
> e.printStackTrace();
> }
> }
> }
>
> public class ThreadDeleter extends Thread {
> public void run() {
> System.out.println("Deleter thread started");
> try {
> Session session = repository.login(new
> SimpleCredentials("", "".toCharArray()));
>
> Node rn = session.getRootNode();
> for (NodeIterator ni = rn.getNodes();
> ni.hasNext(); ) {
> Thread.sleep(100);
> Node currentNode = ni.nextNode();
> if
> (currentNode.getName().startsWith("node")) {
> currentNode.remove();
> }
> }
> session.save();
> session.logout();
>
> } catch (Exception e) {
> e.printStackTrace();
> }
> }
> }
> }
>
--
Oliver Rossmueller
Software Engineer and IT-Consultant
Hamburg, Germany
http://www.rossmueller.com
