Hello everyone, I'm using ECJ for rule-creation and -evaluation. Recently I can use ECJ on 20 cores of a server which runs very fast at the beginning. But after a while the CPU-usage goes down to 1 core which I don't understand. The evaluation process looks so: Step 1: Create a valid rule from GPTree Step 2: If rule contains nothing useful skip everything else, set bad score and go to Step 6 Step 3: Rule contains something useful, so load the testdata Step 4: Run the rule through Drools and testdata (Drools is a ruleengine which also runs multithreaded) Step 5: Compare the output of Drools and a goldstandard (the goldstandard and some more information are one time loaded at setup) Step 6: Put the score, returned by the comparison, into the koza fitness I don't know why but after some time, ECJ is only using 1 core. Does someone got an idea where the problem could come from? Greetings Bojan