--- old/src/hotspot/share/runtime/threadSMR.cpp	Tue Nov 21 14:45:02 2017
+++ new/src/hotspot/share/runtime/threadSMR.cpp	Tue Nov 21 14:45:01 2017
@@ -29,7 +29,7 @@
 #include "services/threadService.hpp"
 
 // 'entries + 1' so we always have at least one entry.
-ThreadsList::ThreadsList(int entries) : _length(entries), _threads(NEW_C_HEAP_ARRAY(JavaThread*, entries + 1, mtGC)), _next_list(NULL) {
+ThreadsList::ThreadsList(int entries) : _length(entries), _threads(NEW_C_HEAP_ARRAY(JavaThread*, entries + 1, mtThread)), _next_list(NULL) {
   *(JavaThread**)(_threads + entries) = NULL;  // Make sure the extra entry is NULL.
 }
 
--- old/src/hotspot/share/runtime/threadSMR.hpp	Tue Nov 21 14:45:05 2017
+++ new/src/hotspot/share/runtime/threadSMR.hpp	Tue Nov 21 14:45:04 2017
@@ -28,6 +28,55 @@
 #include "memory/allocation.hpp"
 #include "runtime/timer.hpp"
 
+// Thread Safe Memory Reclaimation (Thread-SMR) support.
+//
+// ThreadsListHandles are used to safely perform operations on one or more
+// threads without the risk of the thread or threads exiting during the
+// operation. It is no longer necessary to hold the Threads_lock to safely
+// perform an operation on a target thread.
+//
+// There are several different ways to refer to java.lang.Thread objects
+// so we have a few ways to get a protected JavaThread *:
+//
+// JNI jobject example:
+//   jobject jthread = ...;
+//   :
+//   ThreadsListHandle tlh;
+//   JavaThread* jt = NULL;
+//   bool is_alive = tlh.cv_internal_thread_to_JavaThread(jthread, &jt, NULL);
+//   if (is_alive) {
+//     :  // do stuff with 'jt'...
+//   }
+//
+// JVM/TI jthread example:
+//   jthread thread = ...;
+//   :
+//   JavaThread* jt = NULL;
+//   ThreadsListHandle tlh;
+//   jvmtiError err = JvmtiExport::cv_external_thread_to_JavaThread(tlh.list(), thread, &jt, NULL);
+//   if (err != JVMTI_ERROR_NONE) {
+//     return err;
+//   }
+//   :  // do stuff with 'jt'...
+//
+// JVM/TI oop example (this one should be very rare):
+//   oop thread_obj = ...;
+//   :
+//   JavaThread *jt = NULL;
+//   ThreadsListHandle tlh;
+//   jvmtiError err = JvmtiExport::cv_oop_to_JavaThread(tlh.list(), thread_obj, &jt);
+//   if (err != JVMTI_ERROR_NONE) {
+//     return err;
+//   }
+//   :  // do stuff with 'jt'...
+//
+// A JavaThread * that is included in the ThreadsList that is held by
+// a ThreadsListHandle is protected as long as the ThreadsListHandle
+// remains in scope. The target JavaThread * may have logically exited,
+// but that target JavaThread * will not be deleted until it is no
+// longer protected by a ThreadsListHandle.
+
+
 // A fast list of JavaThreads.
 //
 class ThreadsList : public CHeapObj<mtThread> {
@@ -183,7 +232,7 @@
   uint _index;
 
 public:
-  JavaThreadIteratorWithHandle() : _tlh(), _index(0) {}
+  JavaThreadIteratorWithHandle() : _index(0) {}
 
   uint length() const {
     return _tlh.length();
--- old/test/hotspot/jtreg/runtime/ErrorHandling/ErrorHandler.java	Tue Nov 21 14:45:08 2017
+++ new/test/hotspot/jtreg/runtime/ErrorHandling/ErrorHandler.java	Tue Nov 21 14:45:07 2017
@@ -23,6 +23,7 @@
 
 /*
  * @test
+ * @requires (vm.debug == true)
  * @bug 6888954
  * @bug 8015884
  * @summary Exercise HotSpot error handling code by invoking java with
@@ -39,6 +40,7 @@
 public class ErrorHandler {
 
     public static OutputAnalyzer runTest(int testcase) throws Exception {
+        // The -XX:ErrorHandlerTest=N option requires debug bits.
         return new OutputAnalyzer(
             ProcessTools.createJavaProcessBuilder(
             "-XX:-TransmitErrorReport", "-XX:-CreateCoredumpOnCrash", "-XX:ErrorHandlerTest=" + testcase)
@@ -46,10 +48,6 @@
     }
 
     public static void main(String[] args) throws Exception {
-        // Test is only applicable for debug builds
-        if (!Platform.isDebugBuild()) {
-            return;
-        }
         // Keep this in sync with hotspot/src/share/vm/utilities/debug.cpp
         int i = 1;
         String[] strings = {
--- old/test/hotspot/jtreg/runtime/ErrorHandling/NestedThreadsListHandleInErrorHandlingTest.java	Tue Nov 21 14:45:11 2017
+++ new/test/hotspot/jtreg/runtime/ErrorHandling/NestedThreadsListHandleInErrorHandlingTest.java	Tue Nov 21 14:45:10 2017
@@ -33,6 +33,7 @@
 
 /*
  * @test
+ * @requires (vm.debug == true)
  * @bug 8167108
  * @summary Nested ThreadsListHandle info should be in error handling output.
  * @modules java.base/jdk.internal.misc
@@ -47,11 +48,7 @@
 public class NestedThreadsListHandleInErrorHandlingTest {
   public static void main(String[] args) throws Exception {
 
-    if (!Platform.isDebugBuild()) {
-        // -XX:ErrorHandlerTest=N option requires debug bits.
-        return;
-    }
-
+    // The -XX:ErrorHandlerTest=N option requires debug bits.
     ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
         "-XX:+UnlockDiagnosticVMOptions",
         "-Xmx100M",
--- old/test/hotspot/jtreg/runtime/ErrorHandling/ThreadsListHandleInErrorHandlingTest.java	Tue Nov 21 14:45:14 2017
+++ new/test/hotspot/jtreg/runtime/ErrorHandling/ThreadsListHandleInErrorHandlingTest.java	Tue Nov 21 14:45:13 2017
@@ -33,6 +33,7 @@
 
 /*
  * @test
+ * @requires (vm.debug == true)
  * @bug 8167108
  * @summary ThreadsListHandle info should be in error handling output.
  * @modules java.base/jdk.internal.misc
@@ -47,11 +48,7 @@
 public class ThreadsListHandleInErrorHandlingTest {
   public static void main(String[] args) throws Exception {
 
-    if (!Platform.isDebugBuild()) {
-        // -XX:ErrorHandlerTest=N option requires debug bits.
-        return;
-    }
-
+    // The -XX:ErrorHandlerTest=N option requires debug bits.
     ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
         "-XX:+UnlockDiagnosticVMOptions",
         "-Xmx100M",