--- /dev/null	2019-04-18 12:37:53.502576822 +0200
+++ new/src/hotspot/share/gc/z/zUncommitter.cpp	2019-05-02 09:57:53.449179113 +0200
@@ -0,0 +1,74 @@
+/*
+ * 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/zHeap.inline.hpp"
+#include "gc/z/zUncommitter.hpp"
+#include "runtime/mutexLocker.hpp"
+#include "runtime/os.hpp"
+
+ZUncommitter::ZUncommitter() :
+    _monitor(Monitor::leaf, "ZUncommitter", false, Monitor::_safepoint_check_never),
+    _stop(false) {
+  set_name("ZUncommitter");
+  create_and_start();
+}
+
+bool ZUncommitter::idle(uint64_t timeout) {
+  // Idle for at least one second
+  const uint64_t expires = os::elapsedTime() + MAX2(timeout, 1ul);
+
+  for (;;) {
+    // We might wake up spuriously from wait, so always recalculate
+    // the timeout after a wakeup to see if we need to wait again.
+    const uint64_t now = os::elapsedTime();
+    const uint64_t remaining = expires - MIN2(expires, now);
+
+    MonitorLocker ml(&_monitor, Monitor::_no_safepoint_check_flag);
+    if (remaining > 0 && !_stop) {
+      ml.wait(remaining * MILLIUNITS);
+    } else {
+      return !_stop;
+    }
+  }
+}
+
+void ZUncommitter::run_service() {
+  for (;;) {
+    // Try uncommit unused memory
+    const uint64_t timeout = ZHeap::heap()->uncommit(ZUncommitDelay);
+
+    log_trace(gc, heap)("Uncommit Timeout: " UINT64_FORMAT "s", timeout);
+
+    // Idle until next attempt
+    if (!idle(timeout)) {
+      return;
+    }
+  }
+}
+
+void ZUncommitter::stop_service() {
+  MonitorLocker ml(&_monitor, Monitor::_no_safepoint_check_flag);
+  _stop = true;
+  ml.notify();
+}