If the name of the Thread Group is "X-Hive Concurrency Test", the values of the ${__threadNum} variable become "Hive Concurrency Test 1 - 1", "Hive Concurrency Test 1 - 2", ... , "Hive Concurrency Test 1 - N" instead of "1", "2", ..., "N" So basically everything after the dash (-) becomes part of the prefix of the ${__threadNum} values. This could be a feature, but to me it looks like a bug. If it is a feature, at least it is a documentation bug.
Indeed, a bug. I've changed indexOf("-") to lastIndexOf("-") and it now works OK. The change has been made in the 2_0 branch
This issue has been migrated to GitHub: https://github.com/apache/jmeter/issues/1507