performance issues with HttpRequestDecoder?

[Shivaram Lingamneni]

I've been trying to write a simple HTTP-based RPC server using Netty 3.2.1.
I basically took the Snoop example server and deleted code from it :-)

I profiled my application and found that a lot of time was being spent in
HttpRequestDecoder.decode. More specifically, it seems to be spinning on
ReplayingDecoderBuffer.readUnsignedByte (and its callee checkReadableBytes).
Has anyone run into this before?

This is my pipeline:

ChannelPipeline pipeline = pipeline();
pipeline.addLast("decoder", new HttpRequestDecoder());
pipeline.addLast("aggregator", new HttpChunkAggregator(1048576));
pipeline.addLast("encoder", new HttpResponseEncoder());
pipeline.addLast("deflater", new HttpContentCompressor());
HTTPRequestHandler handler = new HTTPRequestHandler();
handler.setBridge(bridge);
pipeline.addLast("handler", handler);

And this is the relevant part of my handler:

public void messageReceived(ChannelHandlerContext ctx, MessageEvent event)
throws Exception {
HttpRequest request = (HttpRequest) event.getMessage();
ChannelBuffer content = request.getContent();
String contentString = content.toString(CharsetUtil.UTF_8);
String rpcResponse = bridge.performRPC(contentString);

// Decide whether to close the connection or not.
boolean keepAlive = isKeepAlive(request);

// Build the response object.
HttpResponse response = new DefaultHttpResponse(HTTP_1_1, OK);
response.setContent(ChannelBuffers.copiedBuffer(rpcResponse,
CharsetUtil.UTF_8));
response.setHeader(CONTENT_TYPE, "text/plain; charset=UTF-8");

if (keepAlive) {
// Add 'Content-Length' header only for a keep-alive connection.
response.setHeader(CONTENT_LENGTH, response.getContent().readableBytes());
}

// Write the response.
ChannelFuture future = event.getChannel().write(response);

// Close the non-keep-alive connection after the write operation is done.
if (!keepAlive) {
future.addListener(ChannelFutureListener.CLOSE);
}
}

The expensive code path goes through future.addListener(); I've attached a
clumsy pair of screenshots from my profiler (YourKit 8.x).

Thanks very much for your time.
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