title: How Can I Tell If JMeter Needs More Heap To Produce "Correct" Results?
body: <p>This is a theoretical question that just occurred to me.</p>
  
  <p>Normally when running an JMeter load test, I find the default heap settings are adequate.</p>
  
  <p>Sometimes when running an intensive JMeter load test, JMeter will throw an OutOfMemory exception, indicating it requires more heap (normally).</p>
  
  <p>I'm concerned about the cases inbetween these two. If JMeter does <em>not</em> throw an OutOfMemory, is there any way to reassure myself that garbage-collecting (on JMeter's side) did not adversely affect the results? Do I have to monitor the gc logs everytime I run JMeter?</p>
  
  <p>I suppose the more practical side of this is; can I compare output from two separate JMeter tests where Jmeter used different heap-sizes?</p>
  
  <p>EDIT: One thing I have noticed, is that the Jmeter UI has an icon to indicate that the GC Overhead Limit has been breached. But this comes from the JVM and is triggered where 98% of CPU time is used doing GC and I reckon my results would be skewed long before I reach this point.</p>