ORA-03135: connection lost contact

November started with blues. I recently encountered very strange issue with the custom workflow components. I am not underrating the term strange here but i am in habit of landing into these troubles frequently. My workflows were failing on server intermittently with error log suggesting

ObjMgrLog Error 1 000000044ccc6f90:0 2010-10-31 11:27:23 (oracon.cpp (3255)) SBL-DBC-00108: An error has occurred preparing a Sql statement.

SQLParseAndExecute Execute 5 000000044ccc6f90:0 2010-10-31 11:27:23 ORA-03135: connection lost contact

I was not sure what was causing this failure as there was no issue in the workflow as it was working fine in other environment. The more concerning factor was that there was no specific pattern for the failure of this workflow. But the best part with siebel is regardless of issue your luck never runs out. I found similar post on the siebel support[ID 762888.1] and resolution was to set the below parameter on the custom workflow process manager component level:

Name:OM-Model Cache Maximum parameter

Value: 0

We monitored our workflows for some time and bingo they started running again in good shape. But the change in this parameter comes with disclaimer regarding performance check.