fix: Fix profiling integration test app startup

System property was declared after classname.
Also dump for log file if the application failed to run.

Author: PerfectSlayer

dd-smoke-tests/profiling-integration-tests/src/test/java/datadog/smoketest/CodeHotspotsTest.java

@@ -1,8 +1,8 @@
 package datadog.smoketest;
 
 import static datadog.smoketest.SmokeTestUtils.buildDirectory;
+import static datadog.smoketest.SmokeTestUtils.checkProcessSuccessfullyEnd;
 import static datadog.smoketest.SmokeTestUtils.createProcessBuilder;
-import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
@@ -136,9 +136,7 @@ void testReactive(Duration meanServiceTime, int arrivalRate, double minCoverage)
                 Long.toString(arrivalRate),
                 Integer.toString(timeout))
             .start();
-
-    int ret = targetProcess.waitFor();
-    assertEquals(0, ret);
+    checkProcessSuccessfullyEnd(targetProcess, logFilePath);
 
     long serviceRate = (long) (workers * 1_000_000_000d) / meanServiceTime.toNanos();
     double idleness = Math.max(0d, (serviceRate - arrivalRate) / (double) serviceRate);
@@ -179,9 +177,7 @@ void testBatch() throws Exception {
                 Long.toString(meanServiceTimeNs),
                 Integer.toString(timeout))
             .start();
-
-    int ret = targetProcess.waitFor();
-    assertEquals(0, ret);
+    checkProcessSuccessfullyEnd(targetProcess, logFilePath);
 
     Files.walk(dumpDir)
         .filter(Files::isRegularFile)
@@ -213,9 +209,7 @@ void testSaturatedFanout() throws Exception {
                 Long.toString(meanServiceTimeNs),
                 Integer.toString(timeout))
             .start();
-
-    int ret = targetProcess.waitFor();
-    assertEquals(0, ret);
+    checkProcessSuccessfullyEnd(targetProcess, logFilePath);
 
     Files.walk(dumpDir)
         .filter(Files::isRegularFile)
@@ -240,9 +234,7 @@ void testNativeLibrary(String libraryName) throws Exception {
                 logFilePath,
                 libraryName)
             .start();
-
-    int ret = targetProcess.waitFor();
-    assertEquals(0, ret);
+    checkProcessSuccessfullyEnd(targetProcess, logFilePath);
 
     Files.walk(dumpDir)
         .filter(Files::isRegularFile)
@@ -287,9 +279,7 @@ private void runTestGenerativeStackTraces(String mode, int depth) throws Excepti
                 "1000",
                 mode)
             .start();
-
-    int ret = targetProcess.waitFor();
-    assertEquals(0, ret);
+    checkProcessSuccessfullyEnd(targetProcess, logFilePath);
 
     Files.walk(dumpDir)
         .filter(Files::isRegularFile)

dd-smoke-tests/profiling-integration-tests/src/test/java/datadog/smoketest/SmokeTestUtils.java

@@ -1,7 +1,11 @@
 package datadog.smoketest;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 import datadog.trace.api.config.ProfilingConfig;
 import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -59,17 +63,18 @@ static ProcessBuilder createProcessBuilder(
                 "-XX:+IgnoreUnrecognizedVMOptions",
                 "-XX:+UnlockCommercialFeatures",
                 "-XX:+FlightRecorder",
-                "-Ddd." + ProfilingConfig.PROFILING_TEMPLATE_OVERRIDE_FILE + "=" + templateOverride,
-                "-cp",
-                profilingShadowJar(),
-                targetClass));
+                "-Ddd."
+                    + ProfilingConfig.PROFILING_TEMPLATE_OVERRIDE_FILE
+                    + "="
+                    + templateOverride));
     if (System.getenv("TEST_LIBASYNC") != null) {
       command.add(
           "-Ddd."
               + ProfilingConfig.PROFILING_DATADOG_PROFILER_LIBPATH
               + "="
               + System.getenv("TEST_LIBASYNC"));
     }
+    command.addAll(Arrays.asList("-cp", profilingShadowJar(), targetClass));
     command.addAll(Arrays.asList(args));
     final ProcessBuilder processBuilder = new ProcessBuilder(command);
     processBuilder.directory(new File(buildDirectory()));
@@ -97,4 +102,20 @@ static String agentShadowJar() {
   static String buildDirectory() {
     return System.getProperty("datadog.smoketest.builddir");
   }
+
+  static void checkProcessSuccessfullyEnd(final Process process, final Path log)
+      throws InterruptedException {
+    int exitCode = process.waitFor();
+    if (exitCode != 0) {
+      try {
+        System.out.println(
+            "=== Profiling application log start ==="
+                + String.join("\n", Files.readAllLines(log))
+                + "=== Profiling application log end ===");
+      } catch (IOException e) {
+        throw new RuntimeException(e);
+      }
+    }
+    assertEquals(0, exitCode, "Failed to run profiling process, exited in error");
+  }
 }