> This one: > lucene/core/src/test/org/apache/lucene/search/TestSort.java
Yeah, I figured by comparing the size of these three... So, to make it short -- every thread should get its own Random instance from a call to LuceneTestCase's public static Random random() { return RandomizedContext.current().getRandom(); } More specifically, the inside of this method returns per-thread Random instance. The first time a thread calls this method it initializes to the same (master) seed. These are not super-easy things to rewrite, Andi. Don't know if you want to emulate the entire randomized testing infrastructure or just make it work consistently with one seed. Dawid