[jboss-user] [JBoss Cache: Core Edition] - Re: Stress Tests

manik.surtani@jboss.com do-not-reply at jboss.com
Mon Aug 4 12:50:09 EDT 2008

"lovelyliatroim" wrote : Just back to this question
  | anonymous wrote : 
  |   | I would have thought that having an ISOLATION level of NONE would turn out to be quicker but apparently not. What goes on behind the scenes when its set to "NONE"?. 
  |   | 
  | Any ideas as to why it would perform better with an isolation level set compared to NONE??
  | Thanks,
  | LL

I suspect this has to do with the error levels you are seeing.  With NONE, all access to the cache is unguarded.  Which is good for memory (no lock objects, CHM segments, etc.) and *possibly* good for performance (if there is no contention).  The moment there is contention you will start to see concurrent modification exceptions and this is possibly what JMeter is seeing as an error.  You also need to look at how JMeter calculates this throughput - e.g., if it doesn't count erroneous connections as successful (i.e., remove from numerator), doesn't count them at all (remove from numerator and denominator) or adds the time taken to generate and throw an exception.  :-)

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