Speed improvements for /admin/pages/

[jorrizza]

These changes try to make /admin/pages/ render a lot faster.
It works, albeit not nearly fast enough for > 2000 pages. It's still useful for smaller sites.

A true solution would be to render the page asynchronously in batches or something.

[TeatroIO]

I've prepared a stage to preview changes. Open stage or view logs.

[mtomov]

👍 I think this is great and it would be great to have this merged (not sure if needs a bit of code style cleanup).

I've profiled the production /pages with rack mini profiler and with only about 20-30 pages, the picture is not bells & roses:

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You're saying that this is still not enough, but where is the holdup? If you've eliminated the partial rendering and the SQL, what's there left, which is slowing it down. You might give the MiniProfiler a try (if you haven't done so already), more specifically the Flamegraphs.

[jorrizza]

I've been playing with MiniProfiler and the flamegraphs. The rough conclusion; the next major bottleneck is the Rails router (_path functions etc.). Removing calls to those is another ~ 3x speed up. We can't do that without breaking functionality. The rest is just plumbing needed for rights management and other very useful functions. I think this page is just asking way too much of Rails. Further optimising away calls to ActiveRecord for the per-user folding stuff will only (at max) give a 9% speed boost.

While I agree with you maintainability suffers a lot by shifting rendering of this page to the client; usability will be much better. Right now, even with these optimisations, Alchemy is not usable for sites with more than about 500 pages. Depending on your infrastructure of course.

Results for 469 pages on an Intel i7-5557U, Linux 4.3.0, Ruby 2.1.5 and Unicorn 5.0.1:

[jorrizza]

With the query optimisation just now, still not much better:

[tvdeyen]

This is not necessary, since Alchemy is Ruby >= 2 and utf-8 is default encoding

[jorrizza]

That was added automatically by Emacs. Feel free to remove it, although in my opinion it's not a bad idea to keep it there. Some editors don't detect file encoding automatically.

[tvdeyen]

Closing in favor of #923