Mule Cache - Cluster In Memory - deserialization issue - caching

Question

My Mule 3.9 application exposes a rest end point.
Application is clustered and on-prem managed through Runtime Manager
Condition is: the end point which kicks off the batch process should be singleton meaning only 1 process should be running on the entire cluster. If a rest endpoint is invoked again, it should result into http status 409
For this use case, I have utilized Mule Caching - Clustered - In Memory version with below configuration
<ee:object-store-caching-strategy name="caching_strategy" doc:name="caching_strategy" keyGenerationExpression="some_key" synchronized="false" entryTTL="14400000" persistent="false" />
My flow looks like below -
<flow name="some-flow" doc:description="some-flow">
<message-properties-transformer scope="invocation" doc:name="Intialize Message Properties" mimeType="application/java">
<add-message-property key="messageId" value="#[message.rootId]"/>
</message-properties-transformer>
<ee:cache doc:name="inititiation" cachingStrategy-ref="caching_strategy" >
<logger message="process cache miss" level="INFO" doc:name="process cache miss"/>
<set-payload doc:name="initialize cache map" value="#[{'id' : flowVars.messageId}]" />
</ee:cache>
<choice doc:name="Is process already running ?" >
<when expression="#[payload.id == flowVars.messageId]">
<logger message="New process started" level="INFO" />
</when>
<otherwise>
<logger message="Process is already running" level="WARN" />
</otherwise>
</choice>
</flow>
As you can see, I am putting java.util.HashMap with 1 key-value pair in cache and checking if it already exists or not
<set-payload doc:name="initialize cache map" value="#[{'id' : flowVars.messageId}]" />
Actual functionality works great in the cluster and serves the purpose !
HOWEVER application logs are full of below **WARN** statements
org.mule.util.store.MonitoredObjectStoreWrapper -
Running expirty on org.mule.util.store.ObjectStorePartition#4648ce75 threw java.lang.IllegalArgumentException:
Cannot deserialize with a null classloader:
Cannot deserialize with a null classloader
I am not sure what is issue? The object which is in the cache is java.util.HashMap which is serializable and only key-value pair is of String.
I sense some class loader issue, but could not bring myself close to it.
Does anybody have any clue?
Thanks
Vikas

Answer 1

Had my hands on the ground and managed to resolve the issue with below configuration -
<ee:object-store-caching-strategy name="caching_strategy" doc:name="caching_strategy" keyGenerationExpression="some_key" synchronized="false" >
<!-- this is because my flow eturns different message than cache"
<ee:serializable-event-copy-strategy/>
<!-- manged store without persistance -->
<managed-store storeName="MyTaskInMemoryStoreForClusteredCaching"
maxEntries="1" entryTTL="14400000"
expirationInterval="3660000" persistent="false"/>
</ee:object-store-caching-strategy>