What is the primary use case for asynchronous I/O

My application is not web based, just need to use sockets to service around 1000 clients. Throughput and latency are of utmost importance to me. Currently using select() from NIO but thinking of moving on to asynchronous IO in NIO.2.

1. When should asynchronous I/O be开发者_C百科 used?
2. What is the primary use case for asynchronous I/O?

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If you are using Infiniband networks I would suggest looking at the Asynchronous IO.

Comparing Java 7 Async NIO with NIO.

However if you are using regular ethernet, it is just as likely to slower as faster. The coding is more complicated than using non-blocking IO which is more complicated than using blocking IO.

If latency is of utmost importance I suggest you look at using kernel by-pass network adapters like Solarflare. However if a 100 micro-second latency is acceptable to you, it is unlikely you need this.

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Asynchronous IO is very good in situations where you need to scale to handle many concurrent connections. Historically one way of doing this was to dedicate a thread per connection, but this approach has limitations you can read about here. With Asynchronous IO you can easier handle many things with less threads and thus scale better.

Depending on the problem it might or might not be the right approach as nothing can beat a single thread when it comes to latency. However, this is a very extreme end and means you care about microseconds. In many cases is a trade-off between latency and throughput/scalability.

In any case it comes down to what you want to solve and what your expectations (numbers) need to be. Asynchronous IO is great and many cases and so is synchronous. There might also be other things you might want to consider such as protocol. Multiple clients interested in the same data (streaming) could indicate you want to look at multicast. If traffic is dedicated per client, then that might not be the approach.

Not knowing your latency requirements, but assuming they are not in a few microseconds I would definitely look into asychronous IO just reading you have 1000 clients. Asynchronous IO is by no means slow and synchronous/single thread connections might not scale well for you.