Christmas approaches. The new Ruby release will be soon. 2.6.0-rc1 has dropped. It hasn’t changed that much since I reviewed preview3, but let’s have a quick look at it. Some of the timings have changed in interesting ways. Or boring ways, perhaps, but in a good way.

Quick Results

The JIT is absolutely, 100%, not faster for Rails yet. In fact, for whatever reason, it seems much slower than in preview3. On the other hand it doesn’t have that weird lumpy performance graph from last time - it’s slow, but it’s uniformly and predictably slow (see below.)

Remember how Ruby 2.5.0 had a nice little speed boost over Ruby 2.4? I’m not seeing that with 2.6. It really looks like Ruby 2.6 and 2.5 are the same speed. I actually got 2.6 looking very slightly slower in my measurements (see the graph.) But it’s within the margin of error — and as you can see, far closer together than Ruby 2.4.1 and 2.5, also shown below.

On the plus side, I saw no more segfaults or interpreter errors (some of those happened with preview3.) In my trials, Ruby 2.6 was rock solid, with or without JIT. I suspect some optimizations got removed or temporarily turned off for stability reasons — I know of that happening in at least one case, and there are probably others.

Here’s the raw version: