diff -r 51ae48d8072f -r 3529d0e8d09c src/share/vm/runtime/thread.cpp --- a/src/share/vm/runtime/thread.cpp Wed Aug 13 08:56:44 2008 -0400 +++ b/src/share/vm/runtime/thread.cpp Fri Aug 15 10:08:20 2008 -0700 @@ -2756,7 +2756,13 @@ // For now, just manually iterate through them. tc->do_thread(VMThread::vm_thread()); Universe::heap()->gc_threads_do(tc); - tc->do_thread(WatcherThread::watcher_thread()); + { + // Grab the Terminator_lock to prevent watcher_thread from being terminated. + MutexLockerEx mu(Terminator_lock, Mutex::_no_safepoint_check_flag); + WatcherThread *wt = WatcherThread::watcher_thread(); + if (wt != NULL) + tc->do_thread(wt); + } // If CompilerThreads ever become non-JavaThreads, add them here }