I had to run the test code on 2.3.4 many times before I got the
ConcurrentModificationException. I was not able to get a
org.apache.jackrabbit.core.state.ItemStateException or
javax.jcr.InvalidItemStateException on that version.
While I understand that the 1.6 branch is no longer maintained, I would
like to be sure that I understand correct JCR behavior. Is it a bug in
1.6.x that the org.apache.jackrabbit.core.state.ItemStateExceptions are
occurring or that they are being wrapped with a
javax.jcr.RepositoryException rather than a
javax.jcr.InvalidItemStateException? A sample 1.6.5 full stack is:
javax.jcr.RepositoryException: Unable to update item: node /: Child node
entry with id 04afd8db-6515-4997-ac4e-83f066e39f53 has been removed, but
is not present in the changelog: Child node entry with id
04afd8db-6515-4997-ac4e-83f066e39f53 has been removed, but is not
present in the changelog
at org.apache.jackrabbit.core.ItemImpl.save(ItemImpl.java:1134)
at org.apache.jackrabbit.core.SessionImpl.save(SessionImpl.java:915)
at test.JackrabbitTest$1.run(JackrabbitTest.java:38)
at
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Caused by: org.apache.jackrabbit.core.state.ItemStateException: Child
node entry with id 04afd8db-6515-4997-ac4e-83f066e39f53 has been
removed, but is not present in the changelog
at
org.apache.jackrabbit.core.state.SharedItemStateManager.validateModified(SharedItemStateManager.java:1383)
at
org.apache.jackrabbit.core.state.SharedItemStateManager.validateHierarchy(SharedItemStateManager.java:1150)
at
org.apache.jackrabbit.core.state.SharedItemStateManager.access$1100(SharedItemStateManager.java:116)
at
org.apache.jackrabbit.core.state.SharedItemStateManager$Update.begin(SharedItemStateManager.java:717)
at
org.apache.jackrabbit.core.state.SharedItemStateManager.beginUpdate(SharedItemStateManager.java:1473)
at
org.apache.jackrabbit.core.state.SharedItemStateManager.update(SharedItemStateManager.java:1503)
at
org.apache.jackrabbit.core.state.LocalItemStateManager.update(LocalItemStateManager.java:351)
at
org.apache.jackrabbit.core.state.XAItemStateManager.update(XAItemStateManager.java:354)
at
org.apache.jackrabbit.core.state.LocalItemStateManager.update(LocalItemStateManager.java:326)
at
org.apache.jackrabbit.core.state.SessionItemStateManager.update(SessionItemStateManager.java:326)
at org.apache.jackrabbit.core.ItemImpl.save(ItemImpl.java:1128)
... 5 more
org.apache.jackrabbit.core.state.ItemStateException: Child node entry
with id 04afd8db-6515-4997-ac4e-83f066e39f53 has been removed, but is
not present in the changelog
at
org.apache.jackrabbit.core.state.SharedItemStateManager.validateModified(SharedItemStateManager.java:1383)
at
org.apache.jackrabbit.core.state.SharedItemStateManager.validateHierarchy(SharedItemStateManager.java:1150)
at
org.apache.jackrabbit.core.state.SharedItemStateManager.access$1100(SharedItemStateManager.java:116)
at
org.apache.jackrabbit.core.state.SharedItemStateManager$Update.begin(SharedItemStateManager.java:717)
at
org.apache.jackrabbit.core.state.SharedItemStateManager.beginUpdate(SharedItemStateManager.java:1473)
at
org.apache.jackrabbit.core.state.SharedItemStateManager.update(SharedItemStateManager.java:1503)
at
org.apache.jackrabbit.core.state.LocalItemStateManager.update(LocalItemStateManager.java:351)
at
org.apache.jackrabbit.core.state.XAItemStateManager.update(XAItemStateManager.java:354)
at
org.apache.jackrabbit.core.state.LocalItemStateManager.update(LocalItemStateManager.java:326)
at
org.apache.jackrabbit.core.state.SessionItemStateManager.update(SessionItemStateManager.java:326)
at org.apache.jackrabbit.core.ItemImpl.save(ItemImpl.java:1128)
at org.apache.jackrabbit.core.SessionImpl.save(SessionImpl.java:915)
at test.JackrabbitTest$1.run(JackrabbitTest.java:38)
at
java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Thanks!
On 12/22/2011 03:46 PM, Stefan Guggisberg wrote:
On Thu, Dec 22, 2011 at 8:39 PM, Mat Lowery<[email protected]> wrote:
My understanding of concurrent modifications is that I can receive an
InvalidItemStateException if I have a stale view of the repository when my
session is saved or my transaction is committed. However, I can get other
exceptions using the code below. Furthermore, I thought Jackrabbit would
allow concurrent child node additions to a single node given the child node
names were unique.
correct
So I wasn't even expecting an InvalidItemStateException
for the code below.
I understand that locking can prevent the InvalidItemStateException but I'm
using transactions and committing the transaction for the sole purpose of
exposing a lock is something I'd like to avoid at this time. I'd like to
just catch the InvalidItemStateException and alert the user with a friendly
message.
Why do I get the given exceptions for the given code? I can supply full
stacks if necessary; for now, just the class and error message are shown.
strange. i ran your test 20 times in a row on my macbook pro (os-x
10.7, java 6)
against the current head (svn r1222443). none of the runs failed.
cheers
stefan
Jackrabbit 1.6.0:
* org.apache.jackrabbit.core.state.ItemStateException: there's already a
property state instance with id
243f6e39-7a3e-4d48-b051-9b4198a6a16b/{http://www.jcp.org/jcr/1.0}primaryType
* javax.jcr.InvalidItemStateException: Item cannot be saved because it has
been modified externally: node /
* javax.jcr.InvalidItemStateException: node /: the node cannot be saved
because it has been modified externally.
Jackrabbit 1.6.5:
* javax.jcr.InvalidItemStateException: node /: the node cannot be saved
because it has been modified externally.
* javax.jcr.InvalidItemStateException: Item cannot be saved because it has
been modified externally: node /
* org.apache.jackrabbit.core.state.ItemStateException: Child node entry with
id 04afd8db-6515-4997-ac4e-83f066e39f53 has been removed, but is not present
in the changelog
Jackrabbit 2.3.4:
* java.util.ConcurrentModificationException
at java.util.WeakHashMap$HashIterator.nextEntry(WeakHashMap.java:762)
at java.util.WeakHashMap$KeyIterator.next(WeakHashMap.java:795)
at
org.apache.jackrabbit.core.cache.CacheManager.logCacheStats(CacheManager.java:164)
package test;
import java.io.File;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
import javax.jcr.Repository;
import javax.jcr.RepositoryException;
import javax.jcr.Session;
import javax.jcr.SimpleCredentials;
import org.apache.jackrabbit.core.TransientRepository;
public class JackrabbitTest {
public static void main(final String[] args) throws Exception {
File dir = File.createTempFile("jackrabbit-test", "");
dir.delete();
dir.mkdir();
System.out.println("created temporary directory: " +
dir.getAbsolutePath());
dir.deleteOnExit();
final Repository jcrRepo = new TransientRepository(dir);
final AtomicBoolean passed = new AtomicBoolean(true);
final AtomicInteger counter = new AtomicInteger(0);
ExecutorService executor = Executors.newFixedThreadPool(50);
Runnable runnable = new Runnable() {
@Override
public void run() {
try {
Session session = jcrRepo.login(
new SimpleCredentials("admin",
"admin".toCharArray()));
session.getRootNode().addNode("n" +
counter.getAndIncrement()); //unique name
session.save();
session.logout();
} catch (RepositoryException e) {
e.printStackTrace();
passed.set(false);
}
}
};
System.out.println("Running threads");
for (int i = 0; i< 500; i++) {
executor.execute(runnable);
}
executor.shutdown(); //Disable new tasks from being submitted
if (!executor.awaitTermination(120, TimeUnit.SECONDS)) {
System.err.println("timeout");
System.exit(1);
}
if (!passed.get()) {
System.err.println("one or more threads got an exception");
System.exit(1);
} else {
System.out.println("all threads ran with no exceptions");
System.exit(0);
}
}
}
