[JoeAltmaier]

Perhaps too many moving parts. Engineers are criticized for 'reinventing the wheel' and writing code when open source is available. But use too much open source, and you have too many moving parts, you don't know how they work, and things like locks and latency are uncontrollable. A familiar storey!

[prof_hobart]

Apart from the OS (which isn't where the problem lies), there's no open source in it.

The reason there's lots of moving parts is because modern computers, OSs, languages, application servers, libraries, databases etc are built to do a lot of very complicated things.

We could have written the entire application from scratch, not using any 3rd party elements so that we had full control over every element. But that would have taken several orders of magnitude longer to deliver actual useful working software to the users.

[JoeAltmaier]

Or, to be non-Aristotelian about it, some parts could have been dispensed with and appropriate code written for the purpose, and other more robust parts could be kept.

[prof_hobart]

Until you discover the issues, you don't know which bits aren't robust enough.

And rewriting them, along with modifying the rest of the application to use them, takes time and can lead to further unexpected behaviour.

[JoeAltmaier]

The opposite of that. Using somebody else's code, written for a different app in a different environment, is where most unexpected behavior comes from.

Here's the bits that aren't robust enough: any open source that isn't either used by thousands, or used in exactly the way you will be using it.

[prof_hobart]

I would still be mostly using a 3rd part application framework if I rewrote some bit of it that I found problems with. I wouldn't be rewriting the whole lot - that would take forever. So I'd be left with a 95% of the framework being written by the 3rd party and 5% written by my team.

That 95% would still need to interact with my new 5%, and as it was never designed to do that, it could easily introduce new unexpected behaviour. Imagine trying to rip out (for example) the indexing code out of a database because it's performing badly and then rewriting it.

[JoeAltmaier]

Imagine having control over the behavior of your code! That's the advantage of writing it. And I thought we were talking about replacing open source packages, not doing open-heart surgery on a faulty package?