Hi Nandika and all,
During simple load test we observed WSO2 BRS both 2.2.0-SNAPSHOT does OOM
[1]. After further investigation, found that our implementation misuses
drools engine.
When request is received by BRS, It creates knowledgeSession from
KnowledgeBase and feed facts and execute rules.
In Drools there are two types of Knowledge sessions
*(1) Stateful *[2]
Stateless knowledge sessions are long lived and knowledge keeps
reference until they get disposed. In BRS we have binded Stateful sessions
with Axis2 sessions.
*(2) Stateless*. [3]
Stateless knowledge session is similar to a function, feed facts,
execute rules and receive results. Stateless knowledge session simply wraps
Stateful knowledge session and dispose it at the end of execution.
Since the knowledge base[4] keeps reference for Stateful knowledge
sessions, memory consumed by knowledgeBase get increase and goes OOM, *if
we don't dispose them*. At the moment there is no dispose mechanism
included in BRS. Therefore it goes OOM when invoke deployed service
continuously.
To solve this we have to solve two things:
(a) Deviate operations that require stateful or stateless knowledge
sessions.
(b) Dispose stateful knowledge sessions when axis2 session get destroyed
I think to solve above mentioned (a), we need mechanism to deviate
operations require Stateful and Stateless knowledge sessions. One possible
solution is as follows:
Currently our operation config in .rsl file is as follows:
<brs:operation name="[OPERATION_NAME]">
<brs:input namespace="[NAMESPACE]" wrapperElementName="[WRAP_NAME]">
<brs:fact elementName="[ELEMENT_NAME]" namespace="[NAMESPACE]"
type="[FACT_TYPE]"/>
</brs:input>
<brs:output namespace="[NAMESPACE]"
wrapperElementName="[WRAP_NAME]">
<brs:fact elementName="[ELEMENT_NAME]" namespace="[NAMESPACE]"
type="[FACT_TYPE]"/>
</brs:output>
</brs:operation>
To deviate operation which require stateful knowledge sessions from
stateless, we can add new attribute, lets say "*operationType*" whith
possible values "*stateful*" and "*stateless*" so final operation config
will look like as follows:
<brs:operation name="[OPERATION_NAME]" operationType="[OPERATION_TYPE]">
<brs:input namespace="[NAMESPACE]" wrapperElementName="[WRAP_NAME]">
<brs:fact elementName="[ELEMENT_NAME]" namespace="[NAMESPACE]"
type="[FACT_TYPE]"/>
</brs:input>
<brs:output namespace="[NAMESPACE]"
wrapperElementName="[WRAP_NAME]">
<brs:fact elementName="[ELEMENT_NAME]" namespace="[NAMESPACE]"
type="[FACT_TYPE]"/>
</brs:output>
</brs:operation>
When request received to particular operation's messageReceiver, we can
create appropriate statful or stateless knowledge session for it.
WDYT, any ideas?
[1] mail: [BRS] BRS 2.2.0 - snapshot goes OOM in clustered setup during
load test
[2]
https://docs.jboss.org/jbpm/v5.1/javadocs/org/drools/runtime/StatefulKnowledgeSession.html
[3]
https://docs.jboss.org/jbpm/v5.1/javadocs/org/drools/runtime/StatelessKnowledgeSession.html
[4] https://docs.jboss.org/jbpm/v5.1/javadocs/org/drools/KnowledgeBase.html
Thanks,
Milinda
--
Milinda Perera
Software Engineer;
WSO2 Inc. http://wso2.com ,
Mobile: (+94) 714 115 032
_______________________________________________
Dev mailing list
[email protected]
http://wso2.org/cgi-bin/mailman/listinfo/dev
