JVM Garbage collection metrics

2 files changed, 64 insertions, 1 deletions

diff --git a/container-disc/src/test/java/com/yahoo/container/jdisc/metric/GarbageCollectionMetricsTest.java b/container-disc/src/test/java/com/yahoo/container/jdisc/metric/GarbageCollectionMetricsTest.java
new file mode 100644
index 00000000000..76ad430f4b9
--- /dev/null
+++ b/container-disc/src/test/java/com/yahoo/container/jdisc/metric/GarbageCollectionMetricsTest.java
@@ -0,0 +1,60 @@
+package com.yahoo.container.jdisc.metric;
+
+import com.yahoo.jdisc.Metric;
+import org.junit.Test;
+
+import java.lang.management.ManagementFactory;
+import java.time.Clock;
+import java.util.LinkedList;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.is;
+import static org.mockito.Matchers.any;
+import static org.mockito.Matchers.anyString;
+import static org.mockito.Mockito.atLeast;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+/**
+ * @author ollivir
+ */
+public class GarbageCollectionMetricsTest {
+    @Test
+    public void gc_metrics_reported_at_intervals() {
+        Clock clock = mock(Clock.class);
+        Metric metric = mock(Metric.class);
+        int base = ManagementFactory.getGarbageCollectorMXBeans().size();
+
+        long iv = GarbageCollectionMetrics.REPORTING_INTERVAL;
+        when(clock.millis()).thenReturn(10L);
+        GarbageCollectionMetrics garbageCollectionMetrics = new GarbageCollectionMetrics(clock);
+        assertThat(garbageCollectionMetrics.getGcStatistics().keySet().size(), is(base));
+
+        when(clock.millis()).thenReturn(iv);
+        garbageCollectionMetrics.emitMetrics(metric);
+        assertWindowLengths(garbageCollectionMetrics, 2);
+
+        when(clock.millis()).thenReturn(10L + iv);
+        garbageCollectionMetrics.emitMetrics(metric);
+        assertWindowLengths(garbageCollectionMetrics, 3);
+
+        when(clock.millis()).thenReturn(20L + iv);
+        garbageCollectionMetrics.emitMetrics(metric);
+        assertWindowLengths(garbageCollectionMetrics, 3);
+
+        when(clock.millis()).thenReturn(20L + iv + iv);
+        garbageCollectionMetrics.emitMetrics(metric);
+        assertWindowLengths(garbageCollectionMetrics, 2);
+
+        verify(metric, times(base * 4 * 2)).set(anyString(), any(), any());
+    }
+
+    private static void assertWindowLengths(GarbageCollectionMetrics gcm, int count) {
+        for(LinkedList<GarbageCollectionMetrics.GcStats> window: gcm.getGcStatistics().values()) {
+            assertThat(window.size(), is(count));
+        }
+    }
+}
diff --git a/container-disc/src/test/java/com/yahoo/container/jdisc/metric/MetricUpdaterTest.java b/container-disc/src/test/java/com/yahoo/container/jdisc/metric/MetricUpdaterTest.java
index f10af7593a4..e9e04eab3b4 100644
--- a/container-disc/src/test/java/com/yahoo/container/jdisc/metric/MetricUpdaterTest.java
+++ b/container-disc/src/test/java/com/yahoo/container/jdisc/metric/MetricUpdaterTest.java
@@ -5,6 +5,7 @@ import com.yahoo.jdisc.Metric;
 import com.yahoo.jdisc.statistics.ContainerWatchdogMetrics;
 import org.junit.Test;
 
+import java.lang.management.ManagementFactory;
 import java.time.Duration;
 
 import static org.mockito.Matchers.any;
@@ -20,11 +21,13 @@ public class MetricUpdaterTest {
     
     @Test
     public void metrics_are_updated_in_scheduler_cycle() throws InterruptedException {
+        int gcCount = ManagementFactory.getGarbageCollectorMXBeans().size();
+
         Metric metric = mock(Metric.class);
         ContainerWatchdogMetrics containerWatchdogMetrics = mock(ContainerWatchdogMetrics.class);
         new MetricUpdater(new MockScheduler(), metric, containerWatchdogMetrics);
         verify(containerWatchdogMetrics, times(1)).emitMetrics(any());
-        verify(metric, times(8)).set(anyString(), any(), any());
+        verify(metric, times(8 + 2 * gcCount)).set(anyString(), any(), any());
     }
 
     private static class MockScheduler implements MetricUpdater.Scheduler {