If a client tries to start two tests in the same remote engine, then failures may result. This is not really a bug, as it probably does not make sense to run multiple tests in the same engine. But worth recording in case it can be fixed easily - either by allowing multiple concurrent tests, or by preventing them. Sample error from Branch 2.2 (r567702) 2007/08/20 14:41:56 ERROR - jmeter.engine.StandardJMeterEngine: Error occurred compiling the tree: java.util.ConcurrentModificationException at java.util.LinkedHashMap$LinkedHashIterator.nextEntry (LinkedHashMap.java:358) at java.util.LinkedHashMap$ValueIterator.next(LinkedHashMap.java:373) at org.apache.jmeter.testelement.property.PropertyIteratorImpl.next (PropertyIteratorImpl.java:50) at org.apache.jmeter.engine.util.ValueReplacer.replaceValues (ValueReplacer.java:113) at org.apache.jmeter.engine.util.ValueReplacer.replaceValues (ValueReplacer.java:65) at org.apache.jmeter.engine.PreCompiler.addNode(PreCompiler.java:58) at org.apache.jorphan.collections.HashTree.traverse(HashTree.java:956) at org.apache.jmeter.engine.StandardJMeterEngine.compileTree (StandardJMeterEngine.java:174) at org.apache.jmeter.engine.StandardJMeterEngine.run (StandardJMeterEngine.java:316) at java.lang.Thread.run(Thread.java:534) Meanwhile, this is documented as a known restriction.
Fixed in rev 1066684 in release 2.5 *** This bug has been marked as a duplicate of bug 50659 ***
Fixed by preventing client from starting a new test while a test is running.
This issue has been migrated to GitHub: https://github.com/apache/jmeter/issues/1995