liuzqt commented on code in PR #38064:
URL: https://github.com/apache/spark/pull/38064#discussion_r1001073725
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core/src/main/scala/org/apache/spark/util/io/ChunkedByteBuffer.scala:
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@@ -84,6 +91,57 @@ private[spark] class ChunkedByteBuffer(var chunks:
Array[ByteBuffer]) {
}
}
+ /**
+ * 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)
+ val chunksCopy = getChunks()
+ chunksCopy.foreach(buffer => out.writeInt(buffer.limit()))
+ var buffer: Array[Byte] = null
+ val bufferLen = ChunkedByteBuffer.estimateBufferChunkSize(size)
+
+ chunksCopy.foreach { chunk => {
+ if (chunk.hasArray) {
+ // zero copy if the bytebuffer is backed by bytes array
+ out.write(chunk.array(), chunk.arrayOffset(), chunk.limit())
Review Comment:
I think the `array()` will returns the reference of the byte array that
backs this buffer, which should not incur extra copy
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