Fix Batch input issue with Scala Benchmark (apache#12848)

* add initial change

* add fix

* improved usage of Shape as well as warning message on performance

* change into parallel

* drop dropBack

* apply Andrew's comments

* remove add dim inside img 2 pixel

* addressed Naveen's comment

* update comments

Author: lanking520

scala-package/core/src/test/scala/org/apache/mxnet/ShapeSuite.scala

@@ -29,4 +29,19 @@ class ShapeSuite extends FunSuite with BeforeAndAfterAll {
     assert(Shape(1, 2, 3) === Shape(1, 2, 3))
     assert(Shape(1, 2) != Shape(1, 2, 3))
   }
+
+  test("drop") {
+    val s = Shape(1, 2, 3)
+    val s2 = s.drop(1)
+    assert(s == Shape(1, 2, 3))
+    assert(s2 == Shape(2, 3))
+    val s3 = s.drop(2)
+    assert(s3 == Shape(3))
+  }
+
+  test("slice") {
+    val s = Shape(1, 2, 3)
+    val s2 = s.slice(0, 1)
+    assert(s2 == Shape(1))
+  }
 }

scala-package/examples/src/main/scala/org/apache/mxnetexamples/InferBase.scala

@@ -21,7 +21,7 @@ import org.apache.mxnet._
 
 trait InferBase {
 
-  def loadModel(context: Array[Context]): Any
+  def loadModel(context: Array[Context], batchInference : Boolean): Any
   def loadSingleData(): Any
   def loadBatchFileList(batchSize: Int): List[Any]
   def loadInputBatch(source: Any): Any

scala-package/examples/src/main/scala/org/apache/mxnetexamples/benchmark/ScalaInferenceBenchmark.scala

@@ -31,9 +31,9 @@ object ScalaInferenceBenchmark {
 
   private val logger = LoggerFactory.getLogger(classOf[CLIParserBase])
 
-  def loadModel(objectToRun: InferBase, context: Array[Context]):
+  def loadModel(objectToRun: InferBase, context: Array[Context], batchInference : Boolean):
   Any = {
-    objectToRun.loadModel(context)
+    objectToRun.loadModel(context, batchInference)
   }
 
   def loadDataSet(objectToRun: InferBase):
@@ -134,7 +134,7 @@ object ScalaInferenceBenchmark {
       logger.info("Running single inference call")
       // Benchmarking single inference call
       NDArrayCollector.auto().withScope {
-        val loadedModel = loadModel(exampleToBenchmark, context)
+        val loadedModel = loadModel(exampleToBenchmark, context, false)
         val dataSet = loadDataSet(exampleToBenchmark)
         val inferenceTimes = runInference(exampleToBenchmark, loadedModel, dataSet, baseCLI.count)
         printStatistics(inferenceTimes, "single_inference")
@@ -144,7 +144,7 @@ object ScalaInferenceBenchmark {
         logger.info("Running for batch inference call")
         // Benchmarking batch inference call
         NDArrayCollector.auto().withScope {
-          val loadedModel = loadModel(exampleToBenchmark, context)
+          val loadedModel = loadModel(exampleToBenchmark, context, true)
           val batchDataSet = loadBatchDataSet(exampleToBenchmark, baseCLI.batchSize)
           val inferenceTimes = runBatchInference(exampleToBenchmark, loadedModel, batchDataSet)
           printStatistics(inferenceTimes, "batch_inference")

scala-package/examples/src/main/scala/org/apache/mxnetexamples/infer/imageclassifier/ImageClassifierExample.scala

@@ -175,9 +175,11 @@ class CLIParser extends CLIParserBase{
 
 class ImageClassifierExample(CLIParser: CLIParser) extends InferBase{
 
-  override def loadModel(context: Array[Context]): Classifier = {
+  override def loadModel(context: Array[Context],
+                         batchInference : Boolean = false): Classifier = {
     val dType = DType.Float32
-    val inputShape = Shape(1, 3, 224, 224)
+    val batchSize = if (batchInference) CLIParser.batchSize else 1
+    val inputShape = Shape(batchSize, 3, 224, 224)
 
     val inputDescriptor = IndexedSeq(DataDesc("data", inputShape, dType, "NCHW"))
 

scala-package/examples/src/main/scala/org/apache/mxnetexamples/infer/objectdetector/SSDClassifierExample.scala

@@ -203,9 +203,10 @@ class CLIParser extends CLIParserBase {
 
 class SSDClassifierExample(CLIParser: CLIParser)
   extends InferBase {
-  override def loadModel(context: Array[Context]): Any = {
+  override def loadModel(context: Array[Context], batchInference: Boolean = false): Any = {
     val dType = DType.Float32
-    val inputShape = Shape(1, 3, 512, 512)
+    val batchSize = if (batchInference) CLIParser.batchSize else 1
+    val inputShape = Shape(batchSize, 3, 512, 512)
     val inputDescriptors = IndexedSeq(DataDesc("data", inputShape, dType, "NCHW"))
     new ObjectDetector(CLIParser.modelPathPrefix, inputDescriptors, context)
   }

scala-package/examples/src/main/scala/org/apache/mxnetexamples/rnn/TestCharRnn.scala

@@ -115,7 +115,7 @@ class TestCharRnn(CLIParser: CLIParser) extends InferBase {
 
   private var vocab : Map[String, Int] = null
 
-  override def loadModel(context: Array[Context]): Any = {
+  override def loadModel(context: Array[Context], batchInference : Boolean = false): Any = {
     val batchSize = 32
     val buckets = List(129)
     val numHidden = 512

scala-package/infer/src/main/scala/org/apache/mxnet/infer/ImageClassifier.scala

@@ -76,13 +76,16 @@ class ImageClassifier(modelPathPrefix: String,
                     topK: Option[Int] = None): IndexedSeq[IndexedSeq[(String, Float)]] = {
 
     val scaledImage = ImageClassifier.reshapeImage(inputImage, width, height)
-    val pixelsNDArray = ImageClassifier.bufferedImageToPixels(scaledImage, inputShape)
+    val imageShape = inputShape.drop(1)
+    val pixelsNDArray = ImageClassifier.bufferedImageToPixels(scaledImage, imageShape)
+    val imgWithBatchNum = NDArray.api.expand_dims(pixelsNDArray, 0)
     inputImage.flush()
     scaledImage.flush()
+    handler.execute(pixelsNDArray.dispose())
 
-    val output = super.classifyWithNDArray(IndexedSeq(pixelsNDArray), topK)
+    val output = super.classifyWithNDArray(IndexedSeq(imgWithBatchNum), topK)
 
-    handler.execute(pixelsNDArray.dispose())
+    handler.execute(imgWithBatchNum.dispose())
 
     IndexedSeq(output(0))
   }
@@ -97,14 +100,16 @@ class ImageClassifier(modelPathPrefix: String,
   def classifyImageBatch(inputBatch: Traversable[BufferedImage], topK: Option[Int] = None):
   IndexedSeq[IndexedSeq[(String, Float)]] = {
 
-    val imageBatch = ListBuffer[NDArray]()
-    for (image <- inputBatch) {
-      val scaledImage = ImageClassifier.reshapeImage(image, width, height)
-      val pixelsNDArray = ImageClassifier.bufferedImageToPixels(scaledImage, inputShape)
-      imageBatch += pixelsNDArray
-    }
+    val inputBatchSeq = inputBatch.toIndexedSeq
+    val imageBatch = inputBatchSeq.indices.par.map(idx => {
+      val scaledImage = ImageClassifier.reshapeImage(inputBatchSeq(idx), width, height)
+      val imageShape = inputShape.drop(1)
+      val imgND = ImageClassifier.bufferedImageToPixels(scaledImage, imageShape)
+      val imgWithBatch = NDArray.api.expand_dims(imgND, 0).get
+      handler.execute(imgND.dispose())
+      imgWithBatch
+    }).toList
     val op = NDArray.concatenate(imageBatch)
-
     val result = super.classifyWithNDArray(IndexedSeq(op), topK)
     handler.execute(op.dispose())
     handler.execute(imageBatch.foreach(_.dispose()))
@@ -147,9 +152,9 @@ object ImageClassifier {
     * returned by this method after the use.
     * </p>
     * @param resizedImage     BufferedImage to get pixels from
-    * @param inputImageShape  Input shape; for example for resnet it is (1,3,224,224).
+    * @param inputImageShape  Input shape; for example for resnet it is (3,224,224).
                               Should be same as inputDescriptor shape.
-    * @return                 NDArray pixels array
+    * @return                 NDArray pixels array with shape (3, 224, 224) in CHW format
     */
   def bufferedImageToPixels(resizedImage: BufferedImage, inputImageShape: Shape): NDArray = {
     // Get height and width of the image

scala-package/infer/src/main/scala/org/apache/mxnet/infer/ObjectDetector.scala

@@ -72,9 +72,12 @@ class ObjectDetector(modelPathPrefix: String,
   : IndexedSeq[IndexedSeq[(String, Array[Float])]] = {
 
     val scaledImage = ImageClassifier.reshapeImage(inputImage, width, height)
-    val pixelsNDArray = ImageClassifier.bufferedImageToPixels(scaledImage, inputShape)
-    val output = objectDetectWithNDArray(IndexedSeq(pixelsNDArray), topK)
+    val imageShape = inputShape.drop(1)
+    val pixelsNDArray = ImageClassifier.bufferedImageToPixels(scaledImage, imageShape)
+    val pixelsNDWithBatch = NDArray.api.expand_dims(pixelsNDArray, 0)
     handler.execute(pixelsNDArray.dispose())
+    val output = objectDetectWithNDArray(IndexedSeq(pixelsNDWithBatch), topK)
+    handler.execute(pixelsNDWithBatch.dispose())
     output
   }
 
@@ -147,13 +150,16 @@ class ObjectDetector(modelPathPrefix: String,
   def imageBatchObjectDetect(inputBatch: Traversable[BufferedImage], topK: Option[Int] = None):
   IndexedSeq[IndexedSeq[(String, Array[Float])]] = {
 
-    val imageBatch = ListBuffer[NDArray]()
-    for (image <- inputBatch) {
-      val scaledImage = ImageClassifier.reshapeImage(image, width, height)
-      val pixelsNdarray = ImageClassifier.bufferedImageToPixels(scaledImage, inputShape)
-      imageBatch += pixelsNdarray
-    }
-    val op = NDArray.concatenate(imageBatch)
+    val inputBatchSeq = inputBatch.toIndexedSeq
+    val imageBatch = inputBatchSeq.indices.par.map(idx => {
+      val scaledImage = ImageClassifier.reshapeImage(inputBatchSeq(idx), width, height)
+      val imageShape = inputShape.drop(1)
+      val pixelsND = ImageClassifier.bufferedImageToPixels(scaledImage, imageShape)
+      val pixelsNDWithBatch = NDArray.api.expand_dims(pixelsND, 0).get
+      handler.execute(pixelsND.dispose())
+      pixelsNDWithBatch
+    })
+    val op = NDArray.concatenate(imageBatch.toList)
 
     val result = objectDetectWithNDArray(IndexedSeq(op), topK)
     handler.execute(op.dispose())

scala-package/infer/src/main/scala/org/apache/mxnet/infer/Predictor.scala

@@ -181,6 +181,7 @@ class Predictor(modelPathPrefix: String,
 
     // rebind with the new batchSize
     if (batchSize != inputBatchSize) {
+      logger.info(s"Latency increased due to batchSize mismatch $batchSize vs $inputBatchSize")
       val desc = iDescriptors.map((f : DataDesc) => new DataDesc(f.name,
         Shape(f.shape.toVector.patch(batchIndex, Vector(inputBatchSize), 1)), f.dtype, f.layout) )
       mxNetHandler.execute(mod.bind(desc, forceRebind = true,

scala-package/infer/src/test/scala/org/apache/mxnet/infer/ImageClassifierSuite.scala

@@ -65,9 +65,9 @@ class ImageClassifierSuite extends ClassifierSuite with BeforeAndAfterAll {
     val image1 = new BufferedImage(100, 200, BufferedImage.TYPE_BYTE_GRAY)
     val image2 = ImageClassifier.reshapeImage(image1, 2, 2)
 
-    val result = ImageClassifier.bufferedImageToPixels(image2, Shape(1, 3, 2, 2))
+    val result = ImageClassifier.bufferedImageToPixels(image2, Shape(3, 2, 2))
 
-    assert(result.shape == inputDescriptor(0).shape)
+    assert(result.shape == inputDescriptor(0).shape.drop(1))
   }
 
   test("ImageClassifierSuite-testWithInputImage") {