Batch export 3 Timeseries at one RPC call (#836)

* Batch export 3 Timeseries at one RPC call

* Update to use Lists.partition

(cherry picked from commit bf7c35d)

Author: songy23

exporters/stats/stackdriver/src/main/java/io/opencensus/exporter/stats/stackdriver/StackdriverExporterWorkerThread.java

@@ -23,6 +23,7 @@
 import com.google.monitoring.v3.CreateMetricDescriptorRequest;
 import com.google.monitoring.v3.CreateTimeSeriesRequest;
 import com.google.monitoring.v3.ProjectName;
+import com.google.monitoring.v3.TimeSeries;
 import io.opencensus.common.Duration;
 import io.opencensus.stats.View;
 import io.opencensus.stats.ViewData;
@@ -48,6 +49,8 @@ final class StackdriverExporterWorkerThread extends Thread {
   private static final Logger logger =
       Logger.getLogger(StackdriverExporterWorkerThread.class.getName());
 
+  @VisibleForTesting static final int MAX_BATCH_EXPORT_SIZE = 3;
+
   private final long scheduleDelayMillis;
   private final String projectId;
   private final ProjectName projectName;
@@ -113,13 +116,24 @@ void export() {
       registerView(view);
       viewDataList.add(viewManager.getView(view.getName()));
     }
-    CreateTimeSeriesRequest.Builder builder =
-        CreateTimeSeriesRequest.newBuilder().setNameWithProjectName(projectName);
+    List<TimeSeries> timeSeriesList = Lists.newArrayList();
     for (ViewData viewData : viewDataList) {
-      builder.addAllTimeSeries(StackdriverExportUtils.createTimeSeriesList(viewData, projectId));
+      timeSeriesList.addAll(StackdriverExportUtils.createTimeSeriesList(viewData, projectId));
     }
-    if (!builder.getTimeSeriesList().isEmpty()) {
-      metricServiceClient.createTimeSeries(builder.build());
+
+    for (List<TimeSeries> batchedTimeSeries :
+        Lists.partition(timeSeriesList, MAX_BATCH_EXPORT_SIZE)) {
+      // Batch export 3 TimeSeries at one call, to avoid exceeding RPC header size limit.
+      CreateTimeSeriesRequest.Builder builder =
+          CreateTimeSeriesRequest.newBuilder().setNameWithProjectName(projectName);
+      for (TimeSeries timeSeries : batchedTimeSeries) {
+        builder.addTimeSeries(timeSeries);
+      }
+      try {
+        metricServiceClient.createTimeSeries(builder.build());
+      } catch (Throwable e) {
+        logger.log(Level.WARNING, "Exception thrown when exporting TimeSeries.", e);
+      }
     }
   }
 

exporters/stats/stackdriver/src/test/java/io/opencensus/exporter/stats/stackdriver/StackdriverExporterWorkerThreadTest.java

@@ -16,6 +16,7 @@
 
 package io.opencensus.exporter.stats.stackdriver;
 
+import static com.google.common.truth.Truth.assertThat;
 import static org.mockito.Matchers.any;
 import static org.mockito.Matchers.eq;
 import static org.mockito.Mockito.doReturn;
@@ -103,6 +104,11 @@ public void setUp() {
     doReturn(null).when(mockCreateTimeSeriesCallable).call(any(CreateTimeSeriesRequest.class));
   }
 
+  @Test
+  public void testConstants() {
+    assertThat(StackdriverExporterWorkerThread.MAX_BATCH_EXPORT_SIZE).isEqualTo(3);
+  }
+
   @Test
   public void export() throws IOException {
     View view =