--- /dev/null	2019-07-22 09:12:57.024271711 +0200
+++ new/src/hotspot/share/gc/z/zObjArrayAllocator.cpp	2019-08-02 15:16:50.941610795 +0200
@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 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/zObjArrayAllocator.hpp"
+#include "gc/z/zUtils.inline.hpp"
+#include "memory/universe.hpp"
+#include "oops/arrayKlass.hpp"
+#include "runtime/interfaceSupport.inline.hpp"
+#include "runtime/handles.hpp"
+#include "runtime/os.hpp"
+#include "utilities/globalDefinitions.hpp"
+
+// To avoid delaying safepoints, clearing of arrays is split up in segments
+// with safepoint polling inbetween. However, we can't have a not-yet-cleared
+// array of oops on the heap when we safepoint since the GC will then stumble
+// across uninitialized oops. To avoid this we let an array of oops be an
+// array of longs until the clearing has completed. We use longs as substitue
+// for oops because they have the same size and alignment when using ZGC (i.e.
+// compressed oops is disabled). A max segment size of 64K was chosen because
+// it offers a good trade-off between allocation time and time-to-safepoint.
+
+static Klass* substitute_oop_array_klass(Klass* klass) {
+  return klass == Universe::objectArrayKlassObj() ? Universe::longArrayKlassObj() : klass;
+}
+
+ZObjArrayAllocator::ZObjArrayAllocator(Klass* klass, size_t word_size, int length, Thread* thread) :
+    ObjArrayAllocator(substitute_oop_array_klass(klass), word_size, length, false /* do_zero */, thread),
+    _final_klass(klass) {}
+
+oop ZObjArrayAllocator::finish(HeapWord* mem) const {
+  HandleMark hm;
+  Handle array(_thread, ObjArrayAllocator::finish(mem));
+
+  // Clear array
+  const size_t segment_max = ZUtils::bytes_to_words(64 * K);
+  const size_t skip = arrayOopDesc::header_size(ArrayKlass::cast(_klass)->element_type());
+  size_t remaining = _word_size - skip;
+
+  while (remaining > 0) {
+    // Clear segment
+    const size_t segment = MIN2(remaining, segment_max);
+    Copy::zero_to_words((HeapWord*)array() + (_word_size - remaining), segment);
+    remaining -= segment;
+
+    // Safepoint
+    ThreadBlockInVM tbivm((JavaThread*)_thread);
+  }
+
+  if (_klass != _final_klass) {
+    // Set final klass
+    oopDesc::release_set_klass((HeapWord*)array(), _final_klass);
+  }
+
+  return array();
+}