Is Rails 4 going to render JSON as a stream by default?

[Rodrigo Rosenfeld Rosas]

I have some pretty big data to be encoded to JSON in my application and
it would be faster if rendering my data as JSON could be done with a
stream response.

So, if the network is the bottleneck, the clients wouldn't notice some
seconds of delay before starting to receive the JSON response that is
required for the server to process JSON encoding before starting to send
it to the client...

Are you considering any kind of optimization like this for Rails 4?

[Piotr Sarnacki]

As far as I know there is no plans to make it the default, but nothing stops you from using ActionController::Live to stream JSON as soon as you generate it.

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Piotr Sarnacki
http://piotrsarnacki.com

[Rodrigo Rosenfeld Rosas]

It is not as simple as one might think.

It requires streaming support by the JSON library itself since the point is to start streaming the output *before* the JSON encoding is finished.

You should be able to pass the output streaming buffer object to the JSON formatter library. For instance, suppose you have something like this object:

{keyA: 'a value', keyB: anotherObject}

As the JSON formatter library reads this object, it would start with some key, right? Suppose it starts with "keyA". So the browser would get a chunk like this:

{"keyA": "a value"

Then it would get another chunk like:

, "keyB":

And it goes on until all object processing is finished. Of course I just simplified the idea. What would really give a boost in my case would be the ability to use multiple cores to format the JSON by splitting the task in multiple threads (or processes depending on what Ruby implementation the library is targetting to).

Since JSON became the de facto format to exchange data between servers and browsers any effort to speed up its encoding/decoding (specially encoding) would be of much value to any web framework.

I'd love to see some performance improvements over JSON responses.

Unfortunately I don't have time this year to work on such improvements since I'm currently with a very tight deadline that has been already missed due to Sandy's hurricane that affected our collocation service provider in NYC.

Please let me know if I wasn't clear enough of what performance improvements I'm suggesting to Rails 4 with regards to JSON responses.

Best,
Rodrigo.

[Piotr Sarnacki]

On Thu, Nov 1, 2012 at 4:35 PM, Rodrigo Rosenfeld Rosas <rr.r...@gmail.com> wrote:

It is not as simple as one might think.

I'm aware that you need to have the library support for that, but this is not a rails concern. Rails depends on multi_json (well, technically Active Support depends on it) and you can choose any library you want to render JSON with rails. If you need this kind of feature, you should rather talk with maintainers of one of the JSON libraries out there.

 

[Robert Pankowecki]

https://github.com/brianmario/yajl-ruby

Yajl is capable of doing it. So hacking together Yajl and ActionController::Live might give you streaming json as it is produced.

Robert Pankowecki

[Rodrigo Rosenfeld Rosas]

Thank you, Robert, I'll give it a try once Rails 4 is released.