Create initial app and ExecutorService demo.

Author: sarahchen6

dd-smoke-tests/concurrent/build.gradle

@@ -0,0 +1,42 @@
+plugins {
+  id 'java'
+  id 'application'
+}
+
+apply from: "$rootDir/gradle/java.gradle"
+
+description = 'Concurrent Integration Tests.'
+
+repositories {
+  mavenCentral()
+}
+
+dependencies {
+  implementation project(':dd-trace-api')
+  testImplementation project(':dd-smoke-tests')
+
+  testImplementation platform('org.junit:junit-bom:5.10.0')
+  testImplementation 'org.junit.jupiter:junit-jupiter'
+}
+
+application {
+  mainClassName = 'datadog.smoketest.concurrent.ConcurrentApp'
+}
+
+test {
+  useJUnitPlatform()
+}
+
+jar {
+  manifest {
+    attributes(
+      'Main-Class': 'datadog.smoketest.concurrent.ConcurrentApp'
+      )
+  }
+}
+
+//tasks.withType(Test).configureEach {
+//  dependsOn "shadowJar"
+//
+//  jvmArgs "-Ddatadog.smoketest.shadowJar.path=${tasks.shadowJar.archiveFile.get()}"
+//}

dd-smoke-tests/concurrent/src/main/java/datadog/smoketest/concurrent/ConcurrentApp.java

@@ -0,0 +1,18 @@
+package datadog.smoketest.concurrent;
+
+public class ConcurrentApp {
+  public static void main(String[] args) {
+    System.out.println("=====ConcurrentApp start=====");
+
+    // demo ExecutorService
+    demoExecutorService.main(args);
+
+    // demo ForkJoin
+
+    // demo custom spans
+
+    // demo something else?
+
+    System.out.println("=====ConcurrentApp finish=====");
+  }
+}

dd-smoke-tests/concurrent/src/main/java/datadog/smoketest/concurrent/demoExecutorService.java

@@ -0,0 +1,64 @@
+package datadog.smoketest.concurrent;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+
+// examples from https://www.baeldung.com/java-executor-service-tutorial
+public class demoExecutorService {
+  public static void main(String[] args) {
+    System.out.println("=====demoExecutorService start=====");
+
+    // instantiate executorService and result
+    ExecutorService executorService = Executors.newFixedThreadPool(10);
+    List<String> result = new ArrayList<>();
+
+    // create callable task
+    Callable<String> callableTask =
+        () -> {
+          TimeUnit.MILLISECONDS.sleep(300);
+          return "callableTask executed!";
+        };
+
+    // invoke callable tasks three times
+    List<Callable<String>> callableTasks = new ArrayList<>();
+    callableTasks.add(callableTask);
+    callableTasks.add(callableTask);
+    callableTasks.add(callableTask);
+    List<Future<String>> futures;
+    try {
+      futures = executorService.invokeAll(callableTasks);
+    } catch (InterruptedException e) {
+      throw new RuntimeException(e);
+    }
+
+    // add futures result to 'result' var
+    for (Future<String> future : futures) {
+      try {
+        result.add(future.get());
+      } catch (InterruptedException | ExecutionException e) {
+        e.printStackTrace();
+      }
+    }
+
+    // shutdown executorService
+    executorService.shutdown();
+    try {
+      if (!executorService.awaitTermination(800, TimeUnit.MILLISECONDS)) {
+        executorService.shutdownNow();
+      }
+    } catch (InterruptedException e) {
+      executorService.shutdownNow();
+    }
+
+    // print result
+    System.out.println("ExecutorService result: " + result);
+
+    System.out.println("=====demoExecutorService finish=====");
+  }
+}

settings.gradle

@@ -96,6 +96,7 @@ include ':dd-smoke-tests:apm-tracing-disabled'
 include ':dd-smoke-tests:armeria-grpc'
 include ':dd-smoke-tests:backend-mock'
 include ':dd-smoke-tests:cli'
+include 'dd-smoke-tests:concurrent'
 include ':dd-smoke-tests:crashtracking'
 include ':dd-smoke-tests:custom-systemloader'
 include ':dd-smoke-tests:dynamic-config'
@@ -524,4 +525,3 @@ include ':dd-java-agent:benchmark'
 include ':dd-java-agent:benchmark-integration'
 include ':dd-java-agent:benchmark-integration:jetty-perftest'
 include ':dd-java-agent:benchmark-integration:play-perftest'
-