8001384: G1: assert(!is_null(v)) failed: narrow oop value can never be zero
Summary: Flush any deferred card mark before a Java thread exits.
Reviewed-by: brutisso, jmasa
8005875: G1: Kitchensink fails with ParallelGCThreads=0
Summary: Check that the concurrent marking worker gang exists in ConcurrentMark::print_worker_threads_on(). Changes were also reviewed by Vitaly Davidovich <vitalyd@gmail.com>.
Reviewed-by: brutisso