Final callback from terminating worker, as well as upon failure
to construct or start a worker. Removes record of worker from
array, and adjusts counts. If pool is shutting down, tries to
complete termination.
@param wt the worker thread, or null if construction failed
@param ex the exception causing failure, or null if none
Final callback from terminating worker, as well as upon failure to construct or start a worker. Removes record of worker from array, and adjusts counts. If pool is shutting down, tries to complete termination.
@param wt the worker thread, or null if construction failed @param ex the exception causing failure, or null if none