--- /dev/null	2019-10-08 16:01:21.069130487 +0800
+++ new/src/hotspot/share/gc/g1/g1ConcurrentHeapResizeThread.cpp	2020-01-03 17:56:50.339813048 +0800
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2001, 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/g1/g1CollectedHeap.inline.hpp"
+#include "gc/g1/g1ConcurrentHeapResizeThread.hpp"
+#include "gc/g1/g1Policy.hpp"
+
+G1ConcurrentHeapResizeThread::G1ConcurrentHeapResizeThread(G1ConcurrentHeapResize* heap_resize) :
+  ConcurrentGCThread(),
+  _concurrent_heap_resize(heap_resize),
+  _state(Idle),
+  _start_monitor(NULL),
+  _done_monitor(NULL) {
+
+  _start_monitor = new Monitor(Mutex::nonleaf, "Concurrent resize start monitor", true,
+                           Monitor::_safepoint_check_never);
+  _done_monitor = new Monitor(Mutex::nonleaf, "Concurrent resize done monitor", true,
+                           Monitor::_safepoint_check_never);
+
+  set_name("G1 concurrent heap resizer");
+  create_and_start();
+}
+
+void G1ConcurrentHeapResizeThread::run_service() {
+
+  G1CollectedHeap* g1h = G1CollectedHeap::heap();
+  G1Policy* policy = g1h->policy();
+
+  while (!should_terminate()) {
+    // wait until working is set.
+    sleep_before_next_cycle();
+    if (should_terminate()) {
+      break;
+    }
+    concurrent_heap_resize()->do_work();
+    concurrent_heap_resize()->notify_work_done();
+  }
+}
+
+void G1ConcurrentHeapResizeThread::stop_service() {
+  MutexLocker ml(_start_monitor, Mutex::_no_safepoint_check_flag);
+  _start_monitor->notify_all();
+}
+
+void G1ConcurrentHeapResizeThread::sleep_before_next_cycle() {
+  assert(!working(), "should have been cleared");
+
+  MonitorLocker ml(_start_monitor, Mutex::_no_safepoint_check_flag);
+  while (!working() && !should_terminate()) {
+    ml.wait();
+  }
+}