JCS Disable auxiliary cache due ConcurrentModification

Question

i'm working with jcs with more clients of one single remote cache server.

Here the server configuration:

registry.host=xx.xx.xx.xx registry.port=1104

remote.cache.service.port=1104

remote.cache.rmiSocketFactoryTimeoutMillis=5000

remote.cluster.LocalClusterConsistency=true

remote.cluster.AllowClusterGet=true

jcs.default=DC

jcs.default.cacheattributes=org.apache.commons.jcs.engine.CompositeCacheAttributes jcs.default.cacheattributes.MaxObjects=100 jcs.default.cacheattributes.MaxMemoryIdleTimeSeconds=1800 jcs.default.cacheattributes.UseMemoryShrinker=true

jcs.default.elementattributes.IsEternal=false jcs.default.elementattributes=org.apache.commons.jcs.engine.ElementAttributes

jcs.auxiliary.DC=org.apache.commons.jcs.auxiliary.disk.indexed.IndexedDiskCacheFactory jcs.auxiliary.DC.attributes=org.apache.commons.jcs.auxiliary.disk.indexed.IndexedDiskCacheAttributes

jcs.auxiliary.DC.attributes.DiskPath=/home/java/conf/data jcs.auxiliary.DC.attributes.MaxPurgatorySize=1000

jcs.auxiliary.DC.attributes.MaxKeySize=1000 jcs.auxiliary.DC.attributes.OptimizeAtRemoveCount=300 jcs.auxiliary.DC.attributes.OptimizeOnShutdown=true jcs.auxiliary.DC.attributes.ClearDiskOnStartup=true jcs.auxiliary.DC.attributes.DiskLimitType=SIZE

And the client configuration:

jcs.auxiliary.RC=org.apache.commons.jcs.auxiliary.remote.RemoteCacheFactory jcs.auxiliary.RC.attributes=org.apache.commons.jcs.auxiliary.remote.RemoteCacheAttributes jcs.auxiliary.RC.attributes.FailoverServers=xx.xx.xx.xx:1104 jcs.auxiliary.RC.attributes.RemoveUponRemotePut=false

jcs.auxiliary.RC.attributes.Receive=false jcs.auxiliary.RC.elementattributes.UseMemoryShrinker=true

Here the client code put:

    public class JcsSharedCache<K, V> implements ICache<K, V> {
        private CompositeCache<K, V> internal;
        public void put(K key, V value) throws BeCacheException {
            try {
                synchronized(this){
                      internal.update(new CacheElement<>(internal.getCacheName(), key, value, internal.getElementAttributes()));
                 }
            } catch (Exception ex) {
                throw new BeCacheException(ex);
            }

        }
    }

Sometimes a client get a ConcurrentModificationException and jcs disable the remote put. Every client had a synchronyzed version of put, but this happens(in my opinion) when two client try to put something in the same cache concurrently.

Is there a manner to avoid this behavior?

Below the stack trace:

2018-07-10 18:02:52 ERROR RemoteCache:141 - Disabling remote cache due to error: Failed to put [da4a81e6-85df-426a-b6f6-a5b6777b0891] to nodes java.util.ConcurrentModificationException at java.util.HashMap$HashIterator.nextNode(HashMap.java:1442) at java.util.HashMap$KeyIterator.next(HashMap.java:1466) at java.util.HashSet.writeObject(HashSet.java:287) at sun.reflect.GeneratedMethodAccessor135.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1128) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348) at java.util.HashMap.internalWriteEntries(HashMap.java:1790) at java.util.HashMap.writeObject(HashMap.java:1363) at sun.reflect.GeneratedMethodAccessor132.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1128) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1548) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1509) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348) at java.util.ArrayList.writeObject(ArrayList.java:766) at sun.reflect.GeneratedMethodAccessor128.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1128) at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496) at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432) at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178) at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348) at org.apache.commons.jcs.utils.serialization.StandardSerializer.serialize(StandardSerializer.java:55) at org.apache.commons.jcs.utils.serialization.SerializationConversionUtil.getSerializedCacheElement(SerializationConversionUtil.java:74) at org.apache.commons.jcs.auxiliary.remote.AbstractRemoteAuxiliaryCache.processUpdate(AbstractRemoteAuxiliaryCache.java:421) at org.apache.commons.jcs.auxiliary.AbstractAuxiliaryCacheEventLogging.updateWithEventLogging(AbstractAuxiliaryCacheEventLogging.java:65) at org.apache.commons.jcs.auxiliary.AbstractAuxiliaryCacheEventLogging.update(AbstractAuxiliaryCacheEventLogging.java:50) at org.apache.commons.jcs.engine.CacheAdaptor.handlePut(CacheAdaptor.java:96) at org.apache.commons.jcs.engine.AbstractCacheEventQueue$PutEvent.doRun(AbstractCacheEventQueue.java:362) at org.apache.commons.jcs.engine.AbstractCacheEventQueue$AbstractCacheEvent.run(AbstractCacheEventQueue.java:281) at org.apache.commons.jcs.engine.CacheEventQueue$QProcessor.run(CacheEventQueue.java:228)