mridulm commented on code in PR #38064:
URL: https://github.com/apache/spark/pull/38064#discussion_r993007045
##########
core/src/main/scala/org/apache/spark/executor/Executor.scala:
##########
@@ -659,9 +659,9 @@ private[spark] class Executor(
val accumUpdates = task.collectAccumulatorUpdates()
val metricPeaks = metricsPoller.getTaskMetricPeaks(taskId)
// TODO: do not serialize value twice
- val directResult = new DirectTaskResult(valueBytes, accumUpdates,
metricPeaks)
- val serializedDirectResult = ser.serialize(directResult)
- val resultSize = serializedDirectResult.limit()
+ val directResult = new DirectTaskResult(valueByteBuffer, accumUpdates,
metricPeaks)
+ val serializedDirectResult =
SerializerHelper.serializeToChunkedBuffer(ser, directResult)
Review Comment:
Unlike the earlier invocation of `serializeToChunkedBuffer` (L#599) , here
we have a good estimate of the size - something to leverage and minimize the
cost of `serializeToChunkedBuffer`
##########
core/src/main/scala/org/apache/spark/util/io/ChunkedByteBuffer.scala:
##########
@@ -17,21 +17,22 @@
package org.apache.spark.util.io
-import java.io.{File, FileInputStream, InputStream}
+import java.io.{Externalizable, File, FileInputStream, InputStream,
ObjectInput, ObjectOutput, OutputStream}
import java.nio.ByteBuffer
import java.nio.channels.WritableByteChannel
import com.google.common.io.ByteStreams
import com.google.common.primitives.UnsignedBytes
import org.apache.commons.io.IOUtils
-
import org.apache.spark.SparkEnv
+
import org.apache.spark.internal.config
import org.apache.spark.network.buffer.{FileSegmentManagedBuffer,
ManagedBuffer}
import org.apache.spark.network.util.{ByteArrayWritableChannel,
LimitedInputStream}
import org.apache.spark.storage.{EncryptedManagedBuffer, StorageUtils}
import org.apache.spark.unsafe.array.ByteArrayMethods
import org.apache.spark.util.Utils
+import org.apache.spark.util.io.ChunkedByteBuffer.writeBufferToDest
Review Comment:
nit: Replace this import with inline invocation
##########
core/src/main/scala/org/apache/spark/util/io/ChunkedByteBuffer.scala:
##########
@@ -84,6 +92,64 @@ private[spark] class ChunkedByteBuffer(var chunks:
Array[ByteBuffer]) {
}
}
+ /**
+ * write to stream with zero copy if possible
+ */
+ def writeToStream(out: OutputStream): Unit = {
+ var buffer: Array[Byte] = null
+ val bufferLen = 1024 * 1024
+ writeBufferToDest(this, out.write)
+ }
+
+ /**
+ * write to ObjectOutput with zero copy if possible
+ */
+ override def writeExternal(out: ObjectOutput): Unit = {
+ // we want to keep the chunks layout
+ out.writeInt(chunks.length)
+ chunks.foreach(buffer => out.writeInt(buffer.limit()))
+ chunks.foreach(buffer => out.writeBoolean(buffer.isDirect))
+ writeBufferToDest(this, out.write)
+ }
+
+ override def readExternal(in: ObjectInput): Unit = {
+ val chunksNum = in.readInt()
+ val indices = 0 until chunksNum
+ val chunksSize = indices.map(_ => in.readInt())
+ val chunksDirect = indices.map(_ => in.readBoolean())
Review Comment:
Do we have cases where we want to preserve whether the buffer was direct or
not across VM ? The current usecase does not require it ?
+CC @Ngone51 ?
If not, drop this and simplify the impl ?
##########
core/src/main/scala/org/apache/spark/util/io/ChunkedByteBuffer.scala:
##########
@@ -84,6 +92,64 @@ private[spark] class ChunkedByteBuffer(var chunks:
Array[ByteBuffer]) {
}
}
+ /**
+ * write to stream with zero copy if possible
+ */
+ def writeToStream(out: OutputStream): Unit = {
+ var buffer: Array[Byte] = null
+ val bufferLen = 1024 * 1024
+ writeBufferToDest(this, out.write)
+ }
+
+ /**
+ * write to ObjectOutput with zero copy if possible
+ */
+ override def writeExternal(out: ObjectOutput): Unit = {
+ // we want to keep the chunks layout
+ out.writeInt(chunks.length)
+ chunks.foreach(buffer => out.writeInt(buffer.limit()))
+ chunks.foreach(buffer => out.writeBoolean(buffer.isDirect))
+ writeBufferToDest(this, out.write)
+ }
+
+ override def readExternal(in: ObjectInput): Unit = {
+ val chunksNum = in.readInt()
+ val indices = 0 until chunksNum
+ val chunksSize = indices.map(_ => in.readInt())
+ val chunksDirect = indices.map(_ => in.readBoolean())
+ val chunks = new Array[ByteBuffer](chunksNum)
+
+ val copyBufferLen = 1024 * 1024
Review Comment:
Pull this out as a constant - both `serializeToChunkedBuffer` and this
method is relying on this value implicitly for efficiency.
##########
core/src/main/scala/org/apache/spark/serializer/SerializerHelper.scala:
##########
@@ -0,0 +1,45 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.serializer
+
+import java.nio.ByteBuffer
+
+import scala.reflect.ClassTag
+
+import org.apache.spark.internal.Logging
+import org.apache.spark.util.io.{ChunkedByteBuffer,
ChunkedByteBufferOutputStream}
+
+private[spark] object SerializerHelper extends Logging {
+ def serializeToChunkedBuffer[T: ClassTag](
+ serializerInstance: SerializerInstance,
+ t: T): ChunkedByteBuffer = {
+ val cbbos = new ChunkedByteBufferOutputStream(1024 * 1024,
ByteBuffer.allocate)
Review Comment:
The default size here is fairly large - most results are fairly small
(except for a small subset).
Unfortunately, small `chunkSize` leads to suboptimal performance for
`ChunkedByteBufferOutputStream` - this change has a potential for causing
performance regressions - something to watch out for.
##########
core/src/main/scala/org/apache/spark/util/io/ChunkedByteBuffer.scala:
##########
@@ -207,6 +273,41 @@ private[spark] object ChunkedByteBuffer {
}
out.toChunkedByteBuffer
}
+
+ /**
+ * util function writing ChunkedByteBuffer to destination with zero copy if
possible(when
+ * ChunkedByteBuffer is backed by bytes array)
+ * @param src ChunkedByteBuffer as src
+ * @param write write function writing data to destination, following the
semantic of
+ * java.io.outputStream.write(buffer Array[Byte], off Int, len
Int)
+ */
+ private def writeBufferToDest(
+ src: ChunkedByteBuffer,
+ write: (Array[Byte], Int, Int) => Unit): Unit = {
+ var buffer: Array[Byte] = null
+ val bufferLen = 1024 * 1024
+
+ src.chunks.foreach { chunk => {
Review Comment:
Use getChunks instead of chunks directly and simplify the impl.
The `rewind` below, for example, is modifying the buffer directly.
##########
core/src/main/scala/org/apache/spark/util/io/ChunkedByteBuffer.scala:
##########
@@ -207,6 +273,41 @@ private[spark] object ChunkedByteBuffer {
}
out.toChunkedByteBuffer
}
+
+ /**
+ * util function writing ChunkedByteBuffer to destination with zero copy if
possible(when
+ * ChunkedByteBuffer is backed by bytes array)
+ * @param src ChunkedByteBuffer as src
+ * @param write write function writing data to destination, following the
semantic of
+ * java.io.outputStream.write(buffer Array[Byte], off Int, len
Int)
+ */
+ private def writeBufferToDest(
+ src: ChunkedByteBuffer,
+ write: (Array[Byte], Int, Int) => Unit): Unit = {
+ var buffer: Array[Byte] = null
+ val bufferLen = 1024 * 1024
+
+ src.chunks.foreach { chunk => {
+ if (chunk.hasArray) {
+ // zero copy if the bytebuffer is backed by bytes array
+ write(chunk.array(), chunk.arrayOffset(), chunk.limit())
+ } else {
+ // fallback to copy approach
+ if (buffer == null) {
+ buffer = new Array[Byte](bufferLen)
+ }
+ val originalPos = chunk.position()
+ chunk.rewind()
+ var bytesToRead = Math.min(chunk.remaining(), bufferLen)
+ while (bytesToRead > 0) {
+ chunk.get(buffer, 0, bytesToRead)
+ write(buffer, 0, bytesToRead)
+ bytesToRead = Math.min(chunk.remaining(), bufferLen)
+ }
+ chunk.position(originalPos)
+ }
+ }}
Review Comment:
Move this as `writeFully(out: OutputStream)` in `ChunkedByteBuffer` ?
##########
core/src/main/scala/org/apache/spark/util/io/ChunkedByteBuffer.scala:
##########
@@ -84,6 +92,64 @@ private[spark] class ChunkedByteBuffer(var chunks:
Array[ByteBuffer]) {
}
}
+ /**
+ * write to stream with zero copy if possible
+ */
+ def writeToStream(out: OutputStream): Unit = {
+ var buffer: Array[Byte] = null
+ val bufferLen = 1024 * 1024
+ writeBufferToDest(this, out.write)
+ }
Review Comment:
Why do we need this method ?
If not required, removing it will simplify `writeExternal`
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