ConcurrentModificationException in transactional operations

Question

I'm trying to do simple puts on a transactional cache with these settings. The puts do not conflict with each other on their keys.
connection.setAutoCommit(false);
connection.setIsolationLevel(Isolation.READ_COMMITTED);
connection.setEager(false);As soon as a few transactions have completed I start seeing these errors. After that all other transactions also fail with confusing exceptions - some about ClassNotFound and some about txns already being committed.
java.util.ConcurrentModificationException
     at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
     at java.util.AbstractList$Itr.next(AbstractList.java:343)
     at com.tangosol.coherence.transaction.internal.TranscriptImpl.getModifiedTables(TranscriptImpl.java:66)
     at com.tangosol.coherence.transaction.internal.storage.Session.getModifiedTables(Session.java:79)
     at com.tangosol.coherence.transaction.internal.storage.Session.queueOperation(Session.java:35)
     at com.tangosol.coherence.transaction.internal.router.LocalDirector.route(LocalDirector.java:41)
     at com.tangosol.coherence.transaction.internal.Endpoint.dispatch(Endpoint.java:105)
     at com.tangosol.coherence.transaction.internal.OptimisticNamedCacheImpl.invoke(OptimisticNamedCacheImpl.java:708)
     at com.tangosol.coherence.transaction.internal.OptimisticNamedCacheImpl.put(OptimisticNamedCacheImpl.java:370)
java.lang.IllegalStateException: Operation called in illegal state: COMMITTED
     at com.tangosol.coherence.transaction.internal.TransactionImpl.assertStateChange(TransactionImpl.java:313)
     at com.tangosol.coherence.transaction.internal.TransactionImpl.setCommitted(TransactionImpl.java:140)
     at com.tangosol.coherence.transaction.internal.component.ClientAutoCommit.invoke(ClientAutoCommit.java:76)
     at com.tangosol.coherence.transaction.internal.Endpoint.dispatch(Endpoint.java:95)
     at com.tangosol.coherence.transaction.internal.router.StaticEndpointConcern.apply(StaticEndpointConcern.java:48)
     at com.tangosol.coherence.transaction.internal.router.OperationFilter.apply(OperationFilter.java:51)
     at com.tangosol.coherence.transaction.internal.router.OutboundRouterImpl.route(OutboundRouterImpl.java:36)
     at com.tangosol.coherence.transaction.internal.Endpoint.dispatch(Endpoint.java:105)
     at com.tangosol.coherence.transaction.internal.router.StaticEndpointConcern.apply(StaticEndpointConcern.java:48)
     at com.tangosol.coherence.transaction.internal.router.OperationFilter.apply(OperationFilter.java:51)
     at com.tangosol.coherence.transaction.internal.router.OutboundRouterImpl.route(OutboundRouterImpl.java:36)
     at com.tangosol.coherence.transaction.internal.Endpoint.dispatch(Endpoint.java:105)
     at com.tangosol.coherence.transaction.internal.router.StaticEndpointConcern.apply(StaticEndpointConcern.java:48)
     at com.tangosol.coherence.transaction.internal.router.OperationFilter.apply(OperationFilter.java:51)
     at com.tangosol.coherence.transaction.internal.router.OutboundRouterImpl.route(OutboundRouterImpl.java:36)
     at com.tangosol.coherence.transaction.internal.Endpoint.dispatch(Endpoint.java:105)
     at com.tangosol.coherence.transaction.internal.router.StaticEndpointConcern.apply(StaticEndpointConcern.java:48)
     at com.tangosol.coherence.transaction.internal.router.OperationFilter.apply(OperationFilter.java:51)
     at com.tangosol.coherence.transaction.internal.router.OutboundRouterImpl.route(OutboundRouterImpl.java:36)
     at com.tangosol.coherence.transaction.internal.router.LocalDirector.route(LocalDirector.java:56)
     ... 22 moreSometimes:
java.lang.IllegalStateException: Operation called in illegal state: ERROR
...Any ideas?
Thanks,
Ashwin.

Answer 1

I suppose this is the correct way to use optimistic, transactional caches:
* Author: Ashwin Jayaprakash / Date: 1/4/12 / Time: 12:32 PM
public class TxnTest {
    protected static final ThreadLocal<Connection> connections = new ThreadLocal<Connection>();
    protected static DefaultConnectionFactory connectionFactory;
    public static void main(String[] args) throws Exception {
        connectionFactory = new DefaultConnectionFactory();
        for (int i = 0; i < 5; i++) {
            runTest();
    private static void runTest() throws InterruptedException {
        Runnable job = new Runnable() {
            @Override
            public void run() {
                String name = Thread.currentThread().getName();
                for (int i = 0; i < 100; i++) {
                    for (int j = 0; j < 3; j++) {
                        if (j > 0) {
                            System.out.printf("Txn [%s-%d] retry attempt [%d]%n", name, i, j);
                        Connection connection = connectionFactory.createConnection();
                        connection.setAutoCommit(false);
                        connection.setIsolationLevel(Isolation.READ_COMMITTED);
                        connection.setEager(false);
                        OptimisticNamedCache users = connection.getNamedCache("tx-users");
                        try {
                            users.put("bill", new User("bill-" + name, i));
                            users.put("mary", new User("mary-" + name, i));
                            users.put("john", new User("john-" + name, i));
                            connection.commit();
                            break;
                        catch (Exception e) {
                            connection.rollback();
                        finally {
                            connection.close();
        Thread t1 = new Thread(job);
        Thread t2 = new Thread(job);
        t1.start();
        t2.start();
        t1.join();
        t2.join();
        System.out.println("Entries: " + CacheFactory.getCache("tx-users").size());
        for (Object o : CacheFactory.getCache("tx-users").values()) {
            System.out.println("   " + o);
    public static class User implements Serializable {
        String name;
        int age;
        public User() {
        public User(String name, int age) {
            this.name = name;
            this.age = age;
        public String getName() {
            return name;
        public int getAge() {
            return age;
        @Override
        public String toString() {
            final StringBuilder sb = new StringBuilder();
            sb.append(getClass().getName());
            sb.append("{name='").append(name).append('\'');
            sb.append(", age=").append(age);
            sb.append('}');
            return sb.toString();
}