High CPU Usage on OFBiz servers

[msakarwal]

Hello,
We are facing high CPU usage on the production servers and this happens twice a month. I could find out a thread in RUNNABLE state and the immediate one in the Blocked state which is eating CPU(more than 90 %). Following are the logs for

"http-0.0.0.0-8080-Processor7" daemon prio=10 tid=0x083dac00 nid=0x4aa6 runnable [0x41be0000..0x41be20b0]
   java.lang.Thread.State: RUNNABLE
        at java.lang.Class.$$YJP$$isInterface(Native Method)
        at java.lang.Class.isInterface(Class.java)
        at org.ofbiz.base.util.ObjectType.instanceOf(ObjectType.java:425)
        at org.ofbiz.base.util.ObjectType.instanceOf(ObjectType.java:415)
        at org.ofbiz.base.util.ObjectType.instanceOf(ObjectType.java:375)
        at org.ofbiz.base.util.ObjectType.instanceOf(ObjectType.java:343)
        at org.ofbiz.entity.GenericEntity.set(GenericEntity.java:391)
        - locked <0x61f29b38> (a org.ofbiz.entity.GenericValue)
        at org.ofbiz.entity.GenericEntity.setFields(GenericEntity.java:851)
        - locked <0x61f29b38> (a org.ofbiz.entity.GenericValue)


"http-0.0.0.0-8080-Processor6" daemon prio=10 tid=0x080e1800 nid=0x4aa5 waiting for monitor entry [0x41c31000..0x41c33130]
   java.lang.Thread.State: BLOCKED (on object monitor)
        at org.ofbiz.entity.GenericEntity.setFields(GenericEntity.java)
        - waiting to lock <0x61f29b38> (a org.ofbiz.entity.GenericValue)

We are seeing this happening in each and every log we get after the high CPU usage. We could not found any logical mistake in our application code base. The version of OFBiz we are using is 4 and we are using it since 2006. I could suspect some of the methods in GenericEntity.java. But I am not sure. The version of file GenericEntity.java. is $Rev: 418498 $.
Can you please help me out on this issue as its very critical.
Please let me know if you need more information.

Thanks.
Manoj