checking again:
CODE: 198235 LOC total
SPEC: 127708 LOC total
We do the same at Shopify, and running off the edge allow to catch bug much sooner and identify them much easier.
It also very significantly cuts down on maintenance cost because we no longer have to work-around bugs, we can fix them upstream and so a small update.
As for you pointing at the Rails 5 migration taking a very long time, it's true that certain major migrations were a pain this one in particular, but it's because a major API had been removed (attr_protected). We (both Shopify and GitHub) work with the edge also in part to make sure the community won't have to suffer this kind of harsh migrations ever again.
All this to say you are blowing things out of proportion. The Ruby and Rails teams at Shopify and GitHub are not an overhead, they pay for themselves, and any tech company as large as Shopify or GitHub you will find major contributors to the stack they use. e.g. There used to be a JVM team at Twitter (half smaller than Shopify even at peak).
I don't see the JVM team as the same thing as a team dedicated to working off a project's core. The JVM team looks closer to the YJIT project. Making a JIT also calls into question Shopify's scalability: Rails was slow enough that they allowed a JIT to be built internally? That's quite the trade-off to make.
That's the same team (Rails + Ruby)...
> Making a JIT also calls into question Shopify's scalability: Rails was slow enough that they allowed a JIT to be built internally?
You are conflating scaling ability with language speed, there is of course some relation between the two, but it's mostly orthogonal.
At the scale of Shopify (several thousands developers) having a few people focus on improving Rails and Ruby is a drop in the bucket and payoff immensely.
Rails and Ruby are both Open Source projects not backed by for-profit organization. It's perfectly normal for an user of such project to contribute patches... That's how Open Source is supposed to work...
There is plenty of organizations contributing patches to the Linux Kernel (Google, IBM, etc). Using your logic that means Linux is slow enough that Google allowed a new scheduler to be built internally?
That's quite the silly line of reasoning...