Fix slow test on java 8, 11, 17

Author: jack-berg

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/state/DeltaSynchronousMetricStorage.java

@@ -81,13 +81,16 @@ void doRecordDouble(double value, Attributes attributes, Context context) {
     }
   }
 
+  @SuppressWarnings("ThreadPriorityCheck")
   private DeltaAggregatorHandle<T> acquireHandleForRecord(Attributes attributes, Context context) {
     while (true) {
       DeltaAggregatorHandle<T> handle =
           getDeltaAggregatorHandle(this.aggregatorHolder, attributes, context);
       if (handle != null) {
         return handle;
       }
+      // Holder or handle is locked for collection; yield to let the collector advance
+      Thread.yield();
     }
   }
 

sdk/metrics/src/test/java/io/opentelemetry/sdk/metrics/SynchronousInstrumentStressTest.java

@@ -41,7 +41,6 @@
 import io.opentelemetry.sdk.metrics.internal.data.ImmutableMetricData;
 import io.opentelemetry.sdk.metrics.internal.data.ImmutableSumData;
 import io.opentelemetry.sdk.testing.exporter.InMemoryMetricReader;
-import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -65,7 +64,6 @@
 class SynchronousInstrumentStressTest {
 
   private static final String INSTRUMENT_NAME = "instrument";
-  private static final Duration ONE_MICROSECOND = Duration.ofNanos(1000);
   private static final List<Double> BUCKET_BOUNDARIES =
       ExplicitBucketHistogramUtils.DEFAULT_HISTOGRAM_BUCKET_BOUNDARIES;
   private static final double[] BUCKET_BOUNDARIES_ARR =
@@ -93,6 +91,7 @@ void stressTest(
     }
   }
 
+  @SuppressWarnings("ThreadPriorityCheck")
   private void stressTestOnce(
       AggregationTemporality aggregationTemporality,
       InstrumentType instrumentType,
@@ -130,15 +129,17 @@ private void stressTestOnce(
     int threadCount = 4;
     List<Thread> recordThreads = new ArrayList<>();
     CountDownLatch latch = new CountDownLatch(threadCount);
+    CountDownLatch startSignal = new CountDownLatch(1);
     for (int i = 0; i < threadCount; i++) {
       recordThreads.add(
           new Thread(
               () -> {
+                Uninterruptibles.awaitUninterruptibly(startSignal);
                 for (Long measurement : measurements) {
                   for (Attributes attr : attributes) {
                     instrument.record(measurement, attr);
                   }
-                  Uninterruptibles.sleepUninterruptibly(ONE_MICROSECOND);
+                  Thread.yield();
                 }
                 latch.countDown();
               }));
@@ -150,8 +151,9 @@ private void stressTestOnce(
     Thread collectThread =
         new Thread(
             () -> {
+              Uninterruptibles.awaitUninterruptibly(startSignal);
               while (latch.getCount() != 0) {
-                Uninterruptibles.sleepUninterruptibly(ONE_MICROSECOND);
+                Thread.yield();
                 collectedMetrics.addAll(
                     reader.collectAllMetrics().stream()
                         .map(SynchronousInstrumentStressTest::copy)
@@ -163,9 +165,10 @@ private void stressTestOnce(
                       .collect(toList()));
             });
 
-    // Start all the threads
+    // Start all the threads, then release the start signal so they begin simultaneously
     collectThread.start();
     recordThreads.forEach(Thread::start);
+    startSignal.countDown();
 
     // Wait for the collect thread to end, which collects until the record threads are done
     Uninterruptibles.joinUninterruptibly(collectThread);