improve docs

Author: stIncMale

driver-core/src/main/com/mongodb/internal/async/function/AsyncCallbackLoop.java

@@ -128,13 +128,17 @@ boolean run(final boolean trampolining, final SingleResultCallback<Void> afterLo
         // the happens-before relation, the execution contains a data race and the read is allowed to observe the write.
         // If such observation happens when the iteration is executed asynchronously, then we have a false positive.
         // Furthermore, depending on the nature of the value read, it may not be trustworthy.
+        //
+        // Making `trampoliningResult` a `volatile`, or even making it an `AtomicReference`/`AtomicInteger` and calling `compareAndSet`
+        // does not resolve the issue: it gets rid of the data race, but still leave us with a race condition
+        // that allows for false positives.
         boolean[] trampoliningResult = {false};
         sameThreadDetector.set(SameThreadDetectionStatus.PROBING);
         body.run((r, t) -> {
             if (completeIfNeeded(afterLoopCallback, r, t)) {
                 // Bounce if we are trampolining and the iteration was executed synchronously,
-                // trampolining completes and so is the whole loop;
-                // otherwise, the whole loop simply completes.
+                // trampolining completes and so is the loop;
+                // otherwise, the loop simply completes.
                 return;
             }
             if (trampolining) {

driver-core/src/test/unit/com/mongodb/internal/async/VakoTest.java

@@ -42,7 +42,7 @@ class VakoTest {
 
     @BeforeAll
     static void beforeAll() {
-        executor = Executors.newScheduledThreadPool(2);
+        executor = Executors.newScheduledThreadPool(1);
     }
 
     @AfterAll