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Comment by chubot | Hacker News Reader

Nice article, but I wish these would have a date on them!

Joel addressed the build vs. buy argument here (20 years ago).

If it’s a core business function — do it yourself, no matter what.

https://www.joelonsoftware.com/2001/10/14/in-defense-of-not-...

I guess what's not obvious to many people is that maintaining and optimizing the kernel and JVM is a core business function for Twitter (but probably not writing a kernel!). Likewise CPU design is now a core business function for Apple. Anything "down" your dependency stack can be.

On the other hand, software for employees to file expense reports likely isn't, etc.

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I think Dan addresses this in the post. "Core business" just isn't well enough defined to be useful. Why is optimizing the kernel Twitter's core business, but not writing it? Because the ROI on the former is high for Twitter, but the ROI on the latter is low.

If you're going to stretch things to call the kernel maintenance and optimization Twitter's core business, then you have the consequence that you don't know what your core business is until you spend a lot of time exploring which things are going to be effective uses of your money. Imo, that's too much of a stretch.

Yeah now I see it even has the phrase "core business", which he says is vague. I don't think it's that vague if you just add the qualification about "down the stack".

It's hard for me to think anything that should be brought in house that isn't down the stack, i.e. on the critical path to serving Twitter. It's just not obvious to outsiders what is down the stack for a given company (the "I could write Twitter in a weekend" people), but it should be more obvious to people working there.

e.g. the example of expense reports is obviously not down the stack -- if it goes down or is generally terrible, you can still serve your customers. As another example, in the old days, the big tech companies used to actually hire chefs and kitchen staff themselves. These days I believe it's all done through contractors.

Also I'd say the post assumes that saving money is always important... in the earlier stages of a company, they are frequently really wasteful and prefer to grow the business. An example is Dropbox starting on AWS and then building their own data centers to become cost efficient.

Lots of things are "down the stack". The servers, the building they sit in, the electricity that runs the building, and the coal/water/solar/wind that produces that electricity. Should Twitter run a power plant? Maybe they should optimize the design of current power plants? Also, what about the toilets that their programmers use - they could probably be optimized as well!

There may be an ROI for it, but I don't think it's part of their core business. If we extrapolate it out and Twitter becomes the best kernel optimizer on the planet, they still can't really sell kernel optimization as a product.

But one of Dan's point is that it could become a part of their core business - they could launch e.g. a kernel optimization consulting service, much like Apple suddenly expanded into making their own CPUs.

The article list has dates: https://danluu.com/

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