I am working on task involving reading from the socket trading quotes and I need to achieve minimum latency and high throughput.
I started with the simpliest possible java nio prototype like this
ByteBuffer buf = ByteBuffer.allocateDirect(BUFFER_SIZE);
try {
buf.clear();
int numBytesRead = socketChannel.read(buf);
if (numBytesRead == -1) {
socketChannel.close();
} else {
buf.flip();
byte[] byteArrived = new byte[buf.remaining];
buf.get(byteArrived,0,byteArrived.length);
// here we send byteArrived to the parser
}
} catch (IOException e) {
}
I guess it is lame to create byte[] array every time, but due to the lack of knowledge I dont know how to parse ByteBuffer ( because I need to unmarshall byte protocol into messages and pass them into business logic). Can you recommend how to avoid mass garbage creation?
Also I would like to ask about best practices how to organize socket reading with low latency and high throughput? I read about LMAX and disruptor framework and they achieved 6M transactions on the single thread.
You can achieve higher than that with Disruptor and other methods. A lot depends on the size and complexity of message (as well as what you do with the message !!)
If you want to serialize/deserialze with ByteBuffer, use the putXxxx and getXxxx methods. To make this process easier, I suggest putting the length of each message first so you can check you have a full message before attempting to parse it.
You might find this presentation interesting http://vanillajava.blogspot.com/2011/11/low-latency-slides.html