DatagramChannel performance issue

[Remi Forax]

----- Mail original -----
> De: "Alan Bateman" <Alan.Bateman at oracle.com>
> À: "Martin Thompson" <mjpt777 at gmail.com>
> Cc: "nio-dev" <nio-dev at openjdk.java.net>
> Envoyé: Dimanche 2 Septembre 2018 21:48:34
> Objet: Re: DatagramChannel performance issue

> On 02/09/2018 20:06, Martin Thompson wrote:
>> :
>> I'm surprised you have not heard of performance issues with NIO
>> before. Most people I know that work in this space have issues with
>> Java. Maybe there could be better channels to solicit feedback and
>> help Java. Survivor bias would suggest we do not get to hear of the
>> failed cases that have to go with other languages and don't come back
>> to Java for IO code.
> It's important to report bugs performance issues. If folks don't have
> time to submit a bug then sending mail here is okay too. There are
> issues and changes discussed here all the time but mostly in other areas
> of NIO such as charsets, buffers, files, selectors or socket channels.
> DatagramChannel does not come up very often.
> 
>> :
>>
>> As I said I'd be happy to help. What would the process involve and
>> what would be the expectation of my efforts being a worthwhile
>> investment?
> If you are looking to contribute then you'll need to sign the SCA
> (details on the "Contributing" page [1]).

or better the OCA given that signing the SCA now requires a time machine :)

> 
> For the specific issue then I think prototype changes to pass in an area
> of memory to the native method so it can populate it with the
> family/address/port. That will allow you to create the socket address in
> java and avoid the expensive upcalls from the JNI code. You'll need to
> be careful with the endianness but it should otherwise be straight forward.
> 
>>
>>> As regards the benchmarks, can you package these up as and send an
>>> attachment? This is important because we can't accept contributions that
>>> don't come via OpenJDK infrastructure.
>> Attached a stripped down version of the repo.
> Thanks, I will look at them.
> 
> [1] http://openjdk.java.net/contribute/

regards,
Rémi