8371337: [CRaC] Fastdebug build fails when calling OperatingSystemMxBean.getProcessCpuLoad after restore

src/jdk.management/linux/native/libmanagement_ext/UnixOperatingSystem.c

@@ -285,10 +285,10 @@ static double get_cpuload_internal(int which, double *pkernelLoad, CpuLoadTarget
         } else if (get_totalticks(which, pticks) < 0) {
             failed = 1;
         }
+        // After restoring with CRaC the new process can appear 'younger'
+        // than last value in counters - we will return -1 (unavailable).
+        if (!failed && pticks->usedKernel >= tmp.usedKernel) {
 
-        if (!failed) {
-
-            assert(pticks->usedKernel >= tmp.usedKernel);
             kdiff = pticks->usedKernel - tmp.usedKernel;
             tdiff = pticks->total - tmp.total;
             udiff = pticks->used - tmp.used;

test/jdk/jdk/crac/java/lang/management/OperatingSystemMxBeanTest.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2025, Azul Systems, Inc. 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 Azul Systems, 385 Moffett Park Drive, Suite 115, Sunnyvale
+ * CA 94089 USA or visit www.azul.com if you need additional information or
+ * have any questions.
+ */
+
+import com.sun.management.OperatingSystemMXBean;
+import jdk.crac.Core;
+import jdk.test.lib.crac.*;
+
+import java.lang.management.ManagementFactory;
+
+import static jdk.test.lib.Asserts.*;
+
+/*
+ * @test
+ * @requires (os.family == "linux")
+ * @library /test/lib
+ * @build OperatingSystemMxBeanTest
+ * @run driver jdk.test.lib.crac.CracTest
+ */
+public class OperatingSystemMxBeanTest implements CracTest {
+    @Override
+    public void test() throws Exception {
+        // The restore must be in a new process => cannot use simengine
+        new CracBuilder().engine(CracEngine.CRIU).doCheckpointAndRestore();
+    }
+
+    @Override
+    public void exec() throws Exception {
+        OperatingSystemMXBean bean = ManagementFactory.getPlatformMXBean(OperatingSystemMXBean.class);
+        System.out.println("System CPU load:  " + bean.getCpuLoad());
+        System.out.println("Process CPU load: " + bean.getProcessCpuLoad());
+        Core.checkpointRestore();
+        // We're restoring on the same system, so total CPU load should not have failed
+        assertLTE(0.0, bean.getCpuLoad());
+        // Per process ticks should be lower after restore than before checkpoint => load unavailable
+        assertEquals(-1.0, bean.getProcessCpuLoad());
+        // Second invocation should work with the updated value => correct
+        assertLTE(0.0, bean.getProcessCpuLoad());
+    }
+}