memoize gauge snapshots

palantir · Sep 7, 2024 · 660e148 · 660e148
1 parent 9f4405b
commit 660e148
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Showing 2 changed files with 35 additions and 15 deletions.
diff --git a/...utobatch/src/main/java/com/palantir/atlasdb/autobatch/AutobatcherTelemetryComponents.java b/...utobatch/src/main/java/com/palantir/atlasdb/autobatch/AutobatcherTelemetryComponents.java
@@ -18,8 +18,11 @@
 
 import com.codahale.metrics.Gauge;
 import com.codahale.metrics.Histogram;
+import com.codahale.metrics.Snapshot;
+import com.google.common.base.Suppliers;
 import com.palantir.tritium.metrics.registry.TaggedMetricRegistry;
 import java.time.Duration;
+import java.util.function.Supplier;
 
 public final class AutobatcherTelemetryComponents {
     private final String safeLoggablePurpose;
@@ -83,24 +86,34 @@ public static AutobatcherTelemetryComponents create(
     }
 
     private void registerGauges() {
+        // capturing a snapshot is expensive, so memoize for 10 milliseconds to reduce overhead during metrics read 50%.
+        Duration memoizeDuration = Duration.ofMillis(10);
+        Supplier<Snapshot> waitTimerSnapshot = Suppliers.memoizeWithExpiration(waitTimer::getSnapshot, memoizeDuration);
+        Supplier<Snapshot> waitTimeHistogramSnapshot =
+                Suppliers.memoizeWithExpiration(waitTimeHistogram::getSnapshot, memoizeDuration);
+        Supplier<Snapshot> runningTimerSnapshot =
+                Suppliers.memoizeWithExpiration(runningTimer::getSnapshot, memoizeDuration);
+        Supplier<Snapshot> totalTimerSnapshot =
+                Suppliers.memoizeWithExpiration(totalTimer::getSnapshot, memoizeDuration);
+
         overheadMetrics.waitTimeNanosP1(
-                (Gauge<Double>) () -> waitTimer.getSnapshot().getValue(0.01));
+                (Gauge<Double>) () -> waitTimerSnapshot.get().getValue(0.01));
         overheadMetrics.waitTimeNanosMedian(
-                (Gauge<Double>) () -> waitTimer.getSnapshot().getValue(0.5));
+                (Gauge<Double>) () -> waitTimerSnapshot.get().getValue(0.5));
 
         overheadMetrics.waitTimePercentageP1(
-                (Gauge<Double>) () -> waitTimeHistogram.getSnapshot().getValue(0.01));
+                (Gauge<Double>) () -> waitTimeHistogramSnapshot.get().getValue(0.01));
         overheadMetrics.waitTimePercentageMedian(
-                (Gauge<Double>) () -> waitTimeHistogram.getSnapshot().getValue(0.5));
+                (Gauge<Double>) () -> waitTimeHistogramSnapshot.get().getValue(0.5));
 
         overheadMetrics.runningTimeNanosP1(
-                (Gauge<Double>) () -> runningTimer.getSnapshot().getValue(0.01));
+                (Gauge<Double>) () -> runningTimerSnapshot.get().getValue(0.01));
         overheadMetrics.runningTimeNanosMedian(
-                (Gauge<Double>) () -> runningTimer.getSnapshot().getValue(0.5));
+                (Gauge<Double>) () -> runningTimerSnapshot.get().getValue(0.5));
 
         overheadMetrics.totalTimeNanosP1(
-                (Gauge<Double>) () -> totalTimer.getSnapshot().getValue(0.01));
+                (Gauge<Double>) () -> totalTimerSnapshot.get().getValue(0.01));
         overheadMetrics.totalTimeNanosMedian(
-                (Gauge<Double>) () -> totalTimer.getSnapshot().getValue(0.5));
+                (Gauge<Double>) () -> totalTimerSnapshot.get().getValue(0.5));
     }
 }
diff --git a/atlasdb-autobatch/src/test/java/com/palantir/atlasdb/autobatch/DisruptorAutobatcherTest.java b/atlasdb-autobatch/src/test/java/com/palantir/atlasdb/autobatch/DisruptorAutobatcherTest.java
@@ -76,17 +76,24 @@ private void assertWaitTimeAndRunningTimeAndTotalTimeMetricsAreProduced(
     }
 
     private void assertNoWaitTimeAndRunningTimeMetricsAreProduced(TaggedMetricRegistry registry) {
-        assertThat(getWaitTimeHistogram(registry)).isNull();
-        assertThat(getWaitTimePercentageHistogram(registry)).isNull();
-        assertThat(getRunningTimeHistogram(registry)).isNull();
-        assertThat(getTotalTimeHistogram(registry)).isNull();
+        assertThat(getWaitTimeHistogram(registry))
+                .satisfies(histogram -> assertThat(histogram.getCount()).isZero());
+        assertThat(getWaitTimePercentageHistogram(registry))
+                .satisfies(histogram -> assertThat(histogram.getCount()).isZero());
+        assertThat(getRunningTimeHistogram(registry))
+                .satisfies(histogram -> assertThat(histogram.getCount()).isZero());
+        assertThat(getTotalTimeHistogram(registry))
+                .satisfies(histogram -> assertThat(histogram.getCount()).isZero());
     }
 
     private void assertOnlyWaitTimeMetricsAreProduced(TaggedMetricRegistry registry, int waitTimeNanos) {
         assertThat(getWaitTimeHistogram(registry).getSnapshot().getValues()).containsExactly(waitTimeNanos);
-        assertThat(getWaitTimePercentageHistogram(registry)).isNull();
-        assertThat(getRunningTimeHistogram(registry)).isNull();
-        assertThat(getTotalTimeHistogram(registry)).isNull();
+        assertThat(getWaitTimePercentageHistogram(registry))
+                .satisfies(histogram -> assertThat(histogram.getCount()).isZero());
+        assertThat(getRunningTimeHistogram(registry))
+                .satisfies(histogram -> assertThat(histogram.getCount()).isZero());
+        assertThat(getTotalTimeHistogram(registry))
+                .satisfies(histogram -> assertThat(histogram.getCount()).isZero());
     }
 
     private static Histogram getWaitTimeHistogram(TaggedMetricRegistry registry) {