From 96941b12f8b465df21423275f3cd3ade579b4fa1 Mon Sep 17 00:00:00 2001 From: "Zhang, Liye" Date: Thu, 31 Mar 2016 20:17:52 -0700 Subject: [SPARK-14242][CORE][NETWORK] avoid copy in compositeBuffer for frame decoder ## What changes were proposed in this pull request? In this patch, we set the initial `maxNumComponents` to `Integer.MAX_VALUE` instead of the default size ( which is 16) when allocating `compositeBuffer` in `TransportFrameDecoder` because `compositeBuffer` will introduce too many memory copies underlying if `compositeBuffer` is with default `maxNumComponents` when the frame size is large (which result in many transport messages). For details, please refer to [SPARK-14242](https://issues.apache.org/jira/browse/SPARK-14242). ## How was this patch tested? spark unit tests and manual tests. For manual tests, we can reproduce the performance issue with following code: `sc.parallelize(Array(1,2,3),3).mapPartitions(a=>Array(new Array[Double](1024 * 1024 * 50)).iterator).reduce((a,b)=> a).length` It's easy to see the performance gain, both from the running time and CPU usage. Author: Zhang, Liye Closes #12038 from liyezhang556520/spark-14242. --- .../main/java/org/apache/spark/network/util/TransportFrameDecoder.java | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/common/network-common/src/main/java/org/apache/spark/network/util/TransportFrameDecoder.java b/common/network-common/src/main/java/org/apache/spark/network/util/TransportFrameDecoder.java index bd1830e6ab..fcec7dfd0c 100644 --- a/common/network-common/src/main/java/org/apache/spark/network/util/TransportFrameDecoder.java +++ b/common/network-common/src/main/java/org/apache/spark/network/util/TransportFrameDecoder.java @@ -140,7 +140,7 @@ public class TransportFrameDecoder extends ChannelInboundHandlerAdapter { } // Otherwise, create a composite buffer. - CompositeByteBuf frame = buffers.getFirst().alloc().compositeBuffer(); + CompositeByteBuf frame = buffers.getFirst().alloc().compositeBuffer(Integer.MAX_VALUE); while (remaining > 0) { ByteBuf next = nextBufferForFrame(remaining); remaining -= next.readableBytes(); -- cgit v1.2.3