--- /dev/null	2020-02-18 07:38:19.571312140 +0100
+++ new/src/java.base/linux/classes/jdk/internal/platform/CgroupSubsystemFactory.java	2020-02-18 13:40:28.477779074 +0100
@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2020, Red Hat Inc.
+ * 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.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * 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.
+ */
+
+package jdk.internal.platform;
+
+import java.io.IOException;
+import java.lang.System.Logger;
+import java.lang.System.Logger.Level;
+import java.nio.file.Paths;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import jdk.internal.platform.cgroupv1.CgroupV1Subsystem;
+import jdk.internal.platform.cgroupv2.CgroupV2Subsystem;
+
+class CgroupSubsystemFactory {
+
+    private static final String CPU_CTRL = "cpu";
+    private static final String CPUACCT_CTRL = "cpuacct";
+    private static final String CPUSET_CTRL = "cpuset";
+    private static final String BLKIO_CTRL = "blkio";
+    private static final String MEMORY_CTRL = "memory";
+
+    static CgroupMetrics create() {
+        Map<String, CgroupInfo> infos = new HashMap<>();
+        try {
+            List<String> lines = CgroupUtil.readAllLinesPrivileged(Paths.get("/proc/cgroups"));
+            for (String line : lines) {
+                if (line.startsWith("#")) {
+                    continue;
+                }
+                CgroupInfo info = CgroupInfo.fromCgroupsLine(line);
+                switch (info.getName()) {
+                case CPU_CTRL:      infos.put(CPU_CTRL, info); break;
+                case CPUACCT_CTRL:  infos.put(CPUACCT_CTRL, info); break;
+                case CPUSET_CTRL:   infos.put(CPUSET_CTRL, info); break;
+                case MEMORY_CTRL:   infos.put(MEMORY_CTRL, info); break;
+                case BLKIO_CTRL:    infos.put(BLKIO_CTRL, info); break;
+                }
+            }
+        } catch (IOException e) {
+            return null;
+        }
+
+        // For cgroups v1 all controllers need to have non-zero hierarchy id
+        boolean isCgroupsV2 = true;
+        boolean anyControllersEnabled = false;
+        boolean anyCgroupsV2Controller = false;
+        boolean anyCgroupsV1Controller = false;
+        for (CgroupInfo info: infos.values()) {
+            anyCgroupsV1Controller = anyCgroupsV1Controller || info.getHierarchyId() != 0;
+            anyCgroupsV2Controller = anyCgroupsV2Controller || info.getHierarchyId() == 0;
+            isCgroupsV2 = isCgroupsV2 && info.getHierarchyId() == 0;
+            anyControllersEnabled = anyControllersEnabled || info.isEnabled();
+        }
+
+        // If no controller is enabled, return no metrics.
+        if (!anyControllersEnabled) {
+            return null;
+        }
+        // Warn about mixed cgroups v1 and cgroups v2 controllers. The code is
+        // not ready to deal with that on a per-controller basis. Return no metrics
+        // in that case
+        if (anyCgroupsV1Controller && anyCgroupsV2Controller) {
+            Logger logger = System.getLogger("jdk.internal.platform");
+            logger.log(Level.DEBUG, "Mixed cgroupv1 and cgroupv2 not supported. Metrics disabled.");
+            return null;
+        }
+
+        if (isCgroupsV2) {
+            CgroupSubsystem subsystem = CgroupV2Subsystem.getInstance();
+            return subsystem != null ? new CgroupMetrics(subsystem) : null;
+        } else {
+            CgroupV1Subsystem subsystem = CgroupV1Subsystem.getInstance();
+            return subsystem != null ? new CgroupV1MetricsImpl(subsystem) : null;
+        }
+    }
+}