GitHub user caneGuy opened a pull request:
https://github.com/apache/spark/pull/18723
[SPARK-21517][CORE] Avoid copying memory when transfer chunks remotely
## What changes were proposed in this pull request?
In our production cluster,oom happens when NettyBlockRpcServer receive
OpenBlocks message.The reason we observed is below:
When BlockManagerManagedBuffer call ChunkedByteBuffer#toNetty, it will use
Unpooled.wrappedBuffer(ByteBuffer... buffers) which use default
maxNumComponents=16 in low-level CompositeByteBuf.When our component's number
is bigger than 16, it till execute consolidateIfNeeded
int numComponents = this.components.size();
if(numComponents > this.maxNumComponents) {
int capacity =
((CompositeByteBuf.Component)this.components.get(numComponents - 1)).endOffset;
ByteBuf consolidated = this.allocBuffer(capacity);
for(int c = 0; c < numComponents; ++c) {
CompositeByteBuf.Component c1 =
(CompositeByteBuf.Component)this.components.get(c);
ByteBuf b = c1.buf;
consolidated.writeBytes(b);
c1.freeIfNecessary();
}
CompositeByteBuf.Component var7 = new
CompositeByteBuf.Component(consolidated);
var7.endOffset = var7.length;
this.components.clear();
this.components.add(var7);
}
in CompositeByteBuf which will consume some memory.
## How was this patch tested?
Test in production cluster.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/caneGuy/spark zhoukang/fix-chunkbuffer
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/18723.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #18723
----
commit ab82c3ee043fdca6b1da15536c9e28a697856c91
Author: zhoukang <[email protected]>
Date: 2017-07-24T08:15:32Z
[SPARK][CORE] Avoid copying memory when transfer chunks remotely
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