Improve warmup phase for overhead tests (#5700)

* improve warmup phase for overhead tests

* add jfr config file that has just the minimal set of items we care about.

* Update benchmark-overhead/src/test/java/io/opentelemetry/OverheadTests.java

Co-authored-by: Trask Stalnaker <[email protected]>

Co-authored-by: Trask Stalnaker <[email protected]>

Author: breedx-splk

benchmark-overhead/src/test/java/io/opentelemetry/OverheadTests.java

@@ -88,7 +88,7 @@ void runAppOnce(TestConfig config, Agent agent) throws Exception {
     writeStartupTimeFile(agent, start);
 
     if (config.getWarmupSeconds() > 0) {
-      doWarmupPhase(config);
+      doWarmupPhase(config, petclinic);
     }
 
     long testStart = System.currentTimeMillis();
@@ -115,28 +115,37 @@ private void startRecording(Agent agent, GenericContainer<?> petclinic) throws E
       "jcmd",
       "1",
       "JFR.start",
-      "settings=profile",
+      "settings=/app/overhead.jfc",
       "dumponexit=true",
       "name=petclinic",
       "filename=" + outFile
     };
     petclinic.execInContainer(command);
   }
 
-  private void doWarmupPhase(TestConfig testConfig) {
-    long start = System.currentTimeMillis();
-    System.out.println(
-        "Performing startup warming phase for " + testConfig.getWarmupSeconds() + " seconds...");
-    while (TimeUnit.MILLISECONDS.toSeconds(System.currentTimeMillis() - start)
-        < testConfig.getWarmupSeconds()) {
+  private void doWarmupPhase(TestConfig testConfig, GenericContainer<?> petclinic) throws IOException, InterruptedException {
+    System.out.println("Performing startup warming phase for " + testConfig.getWarmupSeconds() + " seconds...");
+
+    // excluding the JFR recording from the warmup causes strange inconsistencies in the results
+    System.out.println("Starting disposable JFR warmup recording...");
+    String[] startCommand = {"jcmd", "1", "JFR.start", "settings=/app/overhead.jfc", "dumponexit=true", "name=warmup", "filename=warmup.jfr"};
+    petclinic.execInContainer(startCommand);
+
+    long deadline = System.currentTimeMillis() + TimeUnit.SECONDS.toMillis(testConfig.getWarmupSeconds());
+    while(System.currentTimeMillis() < deadline) {
       GenericContainer<?> k6 =
           new GenericContainer<>(DockerImageName.parse("loadimpact/k6"))
               .withNetwork(NETWORK)
               .withCopyFileToContainer(MountableFile.forHostPath("./k6"), "/app")
-              .withCommand("run", "-u", "5", "-i", "25", "/app/basic.js")
+              .withCommand("run", "-u", "5", "-i", "200", "/app/basic.js")
               .withStartupCheckStrategy(new OneShotStartupCheckStrategy());
       k6.start();
     }
+
+    System.out.println("Stopping disposable JFR warmup recording...");
+    String[] stopCommand = {"jcmd", "1", "JFR.stop", "name=warmup"};
+    petclinic.execInContainer(stopCommand);
+
     System.out.println("Warmup complete.");
   }
 

benchmark-overhead/src/test/java/io/opentelemetry/containers/PetClinicRestContainer.java

@@ -57,6 +57,8 @@ public GenericContainer<?> build() throws Exception {
             .withExposedPorts(PETCLINIC_PORT)
             .withFileSystemBind(
                 namingConventions.localResults(), namingConventions.containerResults())
+            .withCopyFileToContainer(
+                MountableFile.forClasspathResource("overhead.jfc"), "/app/overhead.jfc")
             .waitingFor(Wait.forHttp("/petclinic/actuator/health").forPort(PETCLINIC_PORT))
             .withEnv("spring_profiles_active", "postgresql,spring-data-jpa")
             .withEnv(