Hotspot still has the code to use either T1 or T2 libthread in Solaris. T1 libthread has been removed from Solaris in release 10. JDK9 requires Solaris 10u9 or higher. It's time to remove the T1 libthread support.
JDK-8074026Deprecated UseBoundThreads, DefaultThreadPriority and NoYieldsInMicrolock VM options still defined in globals.hpp
JDK-8149901[Solaris] Use of -XX:+UseThreadPriorities crashes fastdebug