Fixed race condition on dumping future cleanup.

gradle/dump_hanging_test.gradle

@@ -1,27 +1,40 @@
+import java.util.concurrent.ConcurrentHashMap
 import java.util.concurrent.Executors
+import java.util.concurrent.ScheduledFuture
 import java.util.concurrent.TimeUnit
 
+project.ext.tasksDumps = new ConcurrentHashMap<String, ScheduledFuture<?>>()
+project.ext.taskDumpsScheduler = Executors.newScheduledThreadPool(4, { r ->
+  Thread t = new Thread(r, "dump-scheduler")
+  t.daemon = true
+  t
+})
+
 // Schedule thread and heap dumps collection near test timeout.
 tasks.withType(Test).configureEach { testTask ->
   doFirst {
-    def scheduler = Executors.newSingleThreadScheduledExecutor({ r ->
-      Thread t = new Thread(r, 'dump-scheduler')
-      t.daemon = true
-      t
-    })
+    if (project.ext.tasksDumps.containsKey(testTask.path)) {
+      logger.warn("Taking dumps already scheduled: ${testTask.path}; skipping.")
+      return
+    }
+
+    if (!testTask.timeout.present) {
+      logger.info("No timeout for ${testTask.path}; skipping dumps scheduler.")
+      return
+    }
 
     // Calculate delay for taking dumps as test timeout minus 1 minutes, but no less than 1 minute.
-    def delayMinutes = Math.max(1L, timeout.get().minusMinutes(1).toMinutes())
+    def delayMinutes = Math.max(1L, testTask.timeout.get().minusMinutes(1).toMinutes())
 
-    def future = scheduler.schedule({
-      logger.warn("Taking dumps for: ${testTask.getPath()} after ${delayMinutes} minutes.")
+    def future = project.ext.taskDumpsScheduler.schedule({
+      logger.warn("Taking dumps for: ${testTask.path} after ${delayMinutes} minutes.")
 
       try {
         // Use Gradle's build dir and adjust for CI artifacts collection if needed.
         def dumpsDir = layout.buildDirectory.dir('dumps').map {
           if (providers.environmentVariable("CI").isPresent()) {
             // Move reports into the folder collected by the collect_reports.sh script.
-            new File(it.getAsFile().absolutePath.replace('dd-trace-java/dd-java-agent', 'dd-trace-java/workspace/dd-java-agent'))
+            new File(it.asFile.absolutePath.replace('dd-trace-java/dd-java-agent', 'dd-trace-java/workspace/dd-java-agent'))
           } else {
             it.asFile
           }
@@ -62,22 +75,19 @@ tasks.withType(Test).configureEach { testTask ->
       } catch (Throwable e) {
         logger.warn("Dumping failed: ${e.message}")
       }
-      finally {
-        scheduler.shutdown()
-      }
     }, delayMinutes, TimeUnit.MINUTES)
 
-    // Store handles for cancellation in doLast.
-    testTask.ext.dumpFuture = future
-    testTask.ext.dumpScheduler = scheduler
+    // Store future for cancellation in doLast.
+    project.ext.tasksDumps.put(testTask.path, future)
   }
 
   doLast {
     // Cancel if the task finished before the scheduled dump.
     try {
-      testTask.ext.dumpFuture?.cancel(false)
-    } finally {
-      testTask.ext.dumpScheduler?.shutdownNow()
+      def future = project.ext.tasksDumps.remove(testTask.path)
+      future?.cancel(false)
+    } catch(Throwable e) {
+      logger.warn("Failed to cancel dump future for ${testTask.path}: ${e.message}")
     }
   }
 }