Addressed review comments

core/src/main/scala/org/apache/spark/internal/config/package.scala

@@ -2047,8 +2047,8 @@ package object config {
       .doc("The max size of a batch of shuffle blocks to be grouped into a single push request.")
       .version("3.1.0")
       .bytesConf(ByteUnit.BYTE)
-      // 2m is also the default value for TransportConf#memoryMapBytes so it is better to have
-      // the batch size greater than 2m. If it defaults to 2m as well it is very likely that each
+      // Default is 3m because it is greater than 2m which is the default value for
+      // TransportConf#memoryMapBytes. If this defaults to 2m as well it is very likely that each
       // batch of block will be loaded in memory with memory mapping, which has higher overhead
       // with small MB sized chunk of data.
       .createWithDefaultString("3m")

core/src/test/scala/org/apache/spark/shuffle/ShuffleBlockPusherSuite.scala

@@ -334,6 +334,8 @@ class ShuffleBlockPusherSuite extends SparkFunSuite with BeforeAndAfterEach {
     }
 
     def runPendingTasks(): Unit = {
+      // This ensures that all the submitted tasks - updateStateAndCheckIfPushMore and pushUpToMax
+      // are run synchronously.
       while (!tasks.isEmpty) {
         tasks.take().run()
       }