--- /dev/null	2019-02-14 11:31:37.500399000 +0100
+++ new/src/hotspot/share/gc/z/zNMethodTableIteration.cpp	2019-02-20 21:51:25.531075219 +0100
@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2017, 2019, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+#include "precompiled.hpp"
+#include "gc/z/zNMethodClosure.hpp"
+#include "gc/z/zNMethodTableEntry.hpp"
+#include "gc/z/zNMethodTableIteration.hpp"
+#include "runtime/atomic.hpp"
+#include "utilities/debug.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+ZNMethodTableIteration::ZNMethodTableIteration() :
+    _table(NULL),
+    _size(0),
+    _claimed(0) {}
+
+bool ZNMethodTableIteration::in_progress() const {
+  return _table != NULL;
+}
+
+void ZNMethodTableIteration::nmethods_do_begin(ZNMethodTableEntry* table, size_t size) {
+  assert(!in_progress(), "precondition");
+
+  _table = table;
+  _size = size;
+  _claimed = 0;
+}
+
+void ZNMethodTableIteration::nmethods_do_end() {
+  assert(_claimed >= _size, "Failed to claim all table entries");
+
+  // Finish iteration
+  _table = NULL;
+}
+
+void ZNMethodTableIteration::nmethods_do(ZNMethodClosure* cl) {
+  for (;;) {
+    // Claim table partition. Each partition is currently sized to span
+    // two cache lines. This number is just a guess, but seems to work well.
+    const size_t partition_size = (ZCacheLineSize * 2) / sizeof(ZNMethodTableEntry);
+    const size_t partition_start = MIN2(Atomic::add(partition_size, &_claimed) - partition_size, _size);
+    const size_t partition_end = MIN2(partition_start + partition_size, _size);
+    if (partition_start == partition_end) {
+      // End of table
+      break;
+    }
+
+    // Process table partition
+    for (size_t i = partition_start; i < partition_end; i++) {
+      const ZNMethodTableEntry entry = _table[i];
+      if (entry.registered()) {
+        cl->do_nmethod(entry.method());
+      }
+    }
+  }
+}