Currently, the jtreg option '-testThreadFactoryPath' doesn't support relativepath.
Below test command will cause test run failed:
jtreg -v:fail,error -nr -w tmp -testThreadFactoryPath:build/linux-x86_64-server-release/images/test/jtreg_test_thread_factory/jtregTestThreadFactory.jar -testThreadFactory:Virtual -jdk:build/linux-x86_64-server-release/images/jdk test/jdk/java/lang/Long/GetLong.java

I think jtreg can support relativepath for option '-testThreadFactoryPath', like to '-jdk' or '-nativepath'.