What are the Netty alternatives for high-performance networking? [closed]

Question

I am in the process of choosing a networking library to implement a client/server system that cannot spare any microsecond. It will implement its own protocol to send and receive messages. I am looking for a good NIO framework that will allow me to easily develop the server and the client, without having to worry too much about the low level selector details. Everyone recommends me Netty but I would like to experiment with 2 or 3 other alternatives before committing my team with a framework. One thing I did not like very much about Netty is how it handles ByteBuffers with its own ByteBuf implementation and reference counting. Can anyone share your thoughts and alternatives?

Answer 1

We have developed a NIO networking library that performs under 2 microseconds over loopback without producing any garbage for the GC. As Peter Lawrey mentioned, the native JDK selector produces a lot of garbage but we have fixed all these garbage leaks by implementing our own epoll selector. Busy waiting the selector thread is great for latency but there must be a balance not to burn the chip or consume a lot of energy. Our selector implementation use low-level tricks to implement a kind of energy saving mode that takes care of that balance.

Besides CoralReactor, you can also take a look on Grizzly and Mina, but we haven't played with these frameworks yet.

For some Netty TCP performance benchmarks you can take a look here.

Answer 2

This is assuming you really want to save every micro-second. Most applications don't have such strict requirements.

If you want to save micro-seconds, you will want to use busy waiting non-blocking NIO for threads on dedicated cpus. This doesn't scale well as you need to have plenty of CPU but does minimise the latency for handling IO. I suggest you also bind the isolated CPUs to minimise jitter.

You will want to avoid using Selectors as they block and/or create quite a bit of garbage adding to GC pauses.

Also to minimise latency you will want to use a low latency, kernel bypass network adapter such as Solarflare.

You will want to use a push parser so long messages can be decoded/parsed as they download. i.e. you won't want to wait until the whole messages is received before starting.

Using these tricks in combination can save 10 - 30 micro-seconds off every request or inbound event.

Netty is a better solution for scalability ie, higher net throughput, but at a small cost to latency, as do most frameworks which are based on support web services where milli-seconds delays are tolerable.