add jmh

Author: amarziali

dd-trace-core/src/jmh/java/datadog/trace/core/CoreTracerClassloaderNamingBenchmark.java

@@ -0,0 +1,62 @@
+package datadog.trace.core;
+
+import static java.util.concurrent.TimeUnit.MICROSECONDS;
+import static java.util.concurrent.TimeUnit.SECONDS;
+
+import datadog.trace.bootstrap.instrumentation.api.AgentSpan;
+import java.util.WeakHashMap;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Level;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Param;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+import org.openjdk.jmh.infra.Blackhole;
+
+@State(Scope.Benchmark)
+@Warmup(iterations = 1, time = 15, timeUnit = SECONDS)
+@Measurement(iterations = 3, time = 30, timeUnit = SECONDS)
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(MICROSECONDS)
+@Fork(value = 1)
+/**
+ * Benchmark (simulateOverhead) Mode Cnt Score Error Units
+ * CoreTracerClassloaderNamingBenchmark.benchSpanCreation false avgt 3 0.747 ± 0.040 us/op
+ * CoreTracerClassloaderNamingBenchmark.benchSpanCreation true avgt 3 0.695 ± 0.106 us/op
+ */
+public class CoreTracerClassloaderNamingBenchmark {
+  CoreTracer tracer;
+
+  WeakHashMap<ClassLoader, String> weakCache;
+
+  @Param({"false", "true"})
+  boolean simulateOverhead;
+
+  @Setup(Level.Iteration)
+  public void init(Blackhole blackhole) {
+    tracer =
+        CoreTracer.builder()
+            .writer(new BlackholeWriter(blackhole, new TraceCounters(), 0))
+            .strictTraceWrites(false)
+            .build();
+    weakCache = new WeakHashMap<>();
+    weakCache.put(Thread.currentThread().getContextClassLoader(), "test");
+  }
+
+  @Benchmark
+  public void benchSpanCreation(Blackhole blackhole) {
+    final AgentSpan span = tracer.startSpan("", "");
+    if (simulateOverhead) {
+      // simulates an extra getContextClassLoader + a WeakHashMap.get
+      weakCache.get(Thread.currentThread().getContextClassLoader());
+    }
+    span.finish();
+    blackhole.consume(span);
+  }
+}