Summary

Re-specify Thread::countStackFrames to unconditionally throw UnsupportedOperationException in advance of removing the method in a future release. The method has been deprecated since Java SE 1.2, and deprecated for removal since Java SE 9.

Problem

This method has always been ill-defined and useless. It requires the target thread to be suspended, an operation that is inherently deadlock prone. The StackWalker API has provided a better solution for stack walking needs since Java SE 9.

Solution

Re-specify Thread::countStackFrames to unconditionally throw UnsupportedOperationException.

Specification

Change specification to:

    /**
     * Throws {@code UnsupportedOperationException}.
     *
     * @return     nothing
     *
     * @deprecated This method was originally designed to count the number of
     *             stack frames but the results were never well-defined and it
     *             depended on thread-suspension.
     *             This method is subject to removal in a future version of Java SE.
     * @see        StackWalker
     */