Fix integration tests failure (#2067)

Fixed integration tests failure on Linux with Kernel 5.16.x

Signed-off-by: Andrey Pleskach <ples@aiven.io>

server/src/main/java/org/opensearch/monitor/os/OsProbe.java

@@ -51,6 +51,7 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
@@ -401,6 +402,7 @@ public class OsProbe {
         long numberOfPeriods = -1;
         long numberOfTimesThrottled = -1;
         long timeThrottledNanos = -1;
+
         for (final String line : lines) {
             final String[] fields = line.split("\\s+");
             switch (fields[0]) {
@@ -415,9 +417,17 @@ public class OsProbe {
                     break;
             }
         }
-        assert numberOfPeriods != -1;
+        if (isCpuStatWarningsLogged.getAndSet(true) == false) {
-        assert numberOfTimesThrottled != -1;
+            if (numberOfPeriods == -1) {
-        assert timeThrottledNanos != -1;
+                logger.warn("Expected to see nr_periods filed but found nothing");
+            }
+            if (numberOfTimesThrottled == -1) {
+                logger.warn("Expected to see nr_throttled filed but found nothing");
+            }
+            if (timeThrottledNanos == -1) {
+                logger.warn("Expected to see throttled_time filed but found nothing");
+            }
+        }
         return new OsStats.Cgroup.CpuStat(numberOfPeriods, numberOfTimesThrottled, timeThrottledNanos);
     }
 
@@ -440,7 +450,7 @@ public class OsProbe {
     @SuppressForbidden(reason = "access /sys/fs/cgroup/cpu")
     List<String> readSysFsCgroupCpuAcctCpuStat(final String controlGroup) throws IOException {
         final List<String> lines = Files.readAllLines(PathUtils.get("/sys/fs/cgroup/cpu", controlGroup, "cpu.stat"));
-        assert lines != null && lines.size() == 3;
+        assert lines != null && lines.isEmpty() == false;
         return lines;
     }
 
@@ -588,11 +598,18 @@ public class OsProbe {
         return OsProbeHolder.INSTANCE;
     }
 
-    OsProbe() {
+    private final Logger logger;
 
+    private AtomicBoolean isCpuStatWarningsLogged = new AtomicBoolean(false);
+
+    OsProbe() {
+        this(LogManager.getLogger(OsProbe.class));
     }
 
-    private final Logger logger = LogManager.getLogger(getClass());
+    /*For testing purpose*/
+    OsProbe(final Logger logger) {
+        this.logger = logger;
+    }
 
     OsInfo osInfo(long refreshInterval, int allocatedProcessors) throws IOException {
         return new OsInfo(

server/src/test/java/org/opensearch/monitor/os/OsProbeTests.java

@@ -50,9 +50,17 @@ import java.util.List;
 import java.util.Locale;
 import java.util.stream.Collectors;
 
+import org.apache.logging.log4j.Logger;
 import org.apache.lucene.util.Constants;
 import org.opensearch.test.OpenSearchTestCase;
 
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.reset;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
 public class OsProbeTests extends OpenSearchTestCase {
 
     public void testOsInfo() throws IOException {
@@ -277,6 +285,24 @@ public class OsProbeTests extends OpenSearchTestCase {
         assertNull(cgroup);
     }
 
+    public void testLogWarnCpuMessageOnlyOnes() {
+        final Logger logger = mock(Logger.class);
+
+        final OsProbe noCpuStatsOsProbe = new OsProbe(logger) {
+            @Override
+            List<String> readSysFsCgroupCpuAcctCpuStat(String controlGroup) throws IOException {
+                return Collections.singletonList("nr_periods 1");
+            }
+        };
+
+        noCpuStatsOsProbe.osStats();
+        // no nr_throttled and throttled_time
+        verify(logger, times(2)).warn(anyString());
+        reset(logger);
+        noCpuStatsOsProbe.osStats();
+        verify(logger, never()).warn(anyString());
+    }
+
     private static List<String> getProcSelfGroupLines(String hierarchy) {
         return Arrays.asList(
             "10:freezer:/",
@@ -361,4 +387,5 @@ public class OsProbeTests extends OpenSearchTestCase {
             }
         };
     }
+
 }