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Systems that defy detailed understanding

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Re: Systems that defy detailed understanding

#31

Post by dragonwriter »

karmakaze wrote: post #30
BurningFrog wrote: post #24

Earlier quoted context omitted.

> The key point is to keep refactoring “continuously“ to match our understanding of the domain, rather than just “adding features”. This is also what I wanted to say. One important part of that is that refactoring is a pretty difficult skill, and many programmers do not have it. So... for those people, some other advice is probably better.

I wish this process was called 'factoring' and you had to be able to name the concept that was being isolated. Often 'refactoring' just means moving code around or isolating code for it's own sake. If a factor was properly isolated you shouldn't have to do that one again. Sometimes you choose different factors, but that's much less common.

> If a factor was properly isolated you shouldn't have to do that one again.

This assumes that later code changes don't undo/blur the factoring, which while ideal is not at all consistently the case in the real world.

Refactoring is a little over arrow of a name, because code hygiene is more than just isolating factors, but the “re” part is right because you are always aiming to remove infelicities that were actively added in previous coding.

Re: Systems that defy detailed understanding

#32

Post by Koshkin »

Ididntdothis wrote: post #22

I often wonder if things would be better if systems were less forgiving. I bet people would pay more attention if the browser stopped rendering on JavaScript errors or misformed HTML/CSS. This forgiveness seems to encourage a culture of sloppiness which tends to spread out. I have the displeasure of looking at quite a bit of PHP code. When I point out that they should fix the hundreds of warnings the usual answer is…

Indeed, less rigidity and higher tolerances lead to reliability - similar to what we do in construction of buildings: a skyscraper would fall one day if it wasn't for its flexibility under effects of elements such as wind.

Re: Systems that defy detailed understanding

#33

Post by naasking »

Koshkin wrote: post #32
Ididntdothis wrote: post #22

I often wonder if things would be better if systems were less forgiving. I bet people would pay more attention if the browser stopped rendering on JavaScript errors or misformed HTML/CSS. This forgiveness seems to encourage a culture of sloppiness which tends to spread out. I have the displeasure of looking at quite a bit of PHP code. When I point out that they should fix the hundreds of warnings the usual answer is…

Indeed, less rigidity and higher tolerances lead to reliability - similar to what we do in construction of buildings: a skyscraper would fall one day if it wasn't for its flexibility under effects of elements such as wind.

That's not an apt analogy. A system with tight tolerances can still be flexible, we just know more precisely how it can flex and when it will break.

A better analogy would be if your construction workers didn't have standard or prescribed bolts in their design, so they just take what's lying around and hammer and weld bits together until it seemed sturdy enough. Suffice it to say, this is not a recipe that would work to build today's sky scrapers. There is considerable design and sanity checking that goes into this stuff which the web at every point completely lacked.

XHTML was a promising start in the right direction, but they unfortunately bungled it.

Re: Systems that defy detailed understanding

#34

Post by twic »

yuliyp wrote: post #23
Ididntdothis wrote: post #22

I often wonder if things would be better if systems were less forgiving. I bet people would pay more attention if the browser stopped rendering on JavaScript errors or misformed HTML/CSS. This forgiveness seems to encourage a culture of sloppiness which tends to spread out. I have the displeasure of looking at quite a bit of PHP code. When I point out that they should fix the hundreds of warnings the usual answer is…

This often devolves into extremely fragile systems instead. For instance, let's say you failed to load an image on your web site. Would you rather the web site still work with the image broken or just completely fail? What if that image is a tracking pixel? What if you failed to load some experimental module? Being able to still do something useful in the face of something not going according to plan is essential to…

Systems need to be robust against uncontrollable failures, like a cosmic ray destroying an image as it travels over the internet, because we can never prevent those.

But systems should quickly and reliably surface bugs, which are controllable failures.

A layer of suffering on top of that simple story is that it's not always clear what is and what is not a controllable failure. Is a logic error in a dependency of some infrastructure tooling somewhere in your stack controllable or not? Somebody somewhere could have avoided making that mistake, but it's not clear that you could.

An additional layer of suffering is that we have a habit of allowing this complexity to creep or flood into our work and telling ourselves that it's inevitable. The author writes:

> Once your system is spread across multiple nodes, we face the possibility of one node failing but not another, or the network itself dropping, reordering, and delaying messages between nodes. The vast majority of complexity in distributed systems arises from this simple possibility.

But somehow, the conclusion isn't "so we shouldn't spread the system across multiple nodes". Yo Martin, can we get the First Law of Distributed Object Design a bit louder for the people at the back?

https://www.drdobbs.com/errant-architectures/184414966

And let us never forget to ask ourselves this question:

https://www.whoownsmyavailability.com/

Re: Systems that defy detailed understanding

#35

Post by svat »

drvortex wrote: post #14

What a long winded article on what has been known to scientists for decades as "emergence". Emergent properties are systems level properties that are not obvious/predictable from properties of individual components. Looking and observing one ant is unlikely to tell you that several of these creatures can build an anthill.

Your comment was very puzzling to me, as I couldn't figure out what kind of misunderstanding about this article would prompt a comment such as this. But finally a possibility occurred to me: perhaps you think the point of this article was simply to say that there exist "systems that defy detailed understanding". It is possible that one could think that, if one went in with preconceived expectations based only on title of the post. (But this is a very dangerous habit in general, as outside of personal blogs like this one, almost always headlines in publications aren't chosen by the author.)

But we all know such systems already: for instance, people! No, this post is a supplement/subsidiary to the previous one ("Computers can be understood" — BTW here's another recent blog post making the same point: https://jvns.ca/blog/debugging-attitude-matters/), carving out exceptions to the general rule, and illustrating concretely why these are exceptions (and what works instead). It is useful to the practitioner as a rule-of-thumb for having a narrow set of criteria for when to avoid aiming to understand fully (and alternative strategies for such cases). Otherwise, it's very easy to throw up one's hands and say "computers are magic; I can't possibly understand this".

(The point of the article here is obvious from even just the first or last paragraphs of the article IMO.)

Re: Systems that defy detailed understanding

#36

Post by k__ »

Ididntdothis wrote: post #22

I often wonder if things would be better if systems were less forgiving. I bet people would pay more attention if the browser stopped rendering on JavaScript errors or misformed HTML/CSS. This forgiveness seems to encourage a culture of sloppiness which tends to spread out. I have the displeasure of looking at quite a bit of PHP code. When I point out that they should fix the hundreds of warnings the usual answer is…

If the web worked like that, it probably wouldn't be so popular today.

Re: Systems that defy detailed understanding

#37

Post by andai »

yuliyp wrote: post #23
Ididntdothis wrote: post #22

I often wonder if things would be better if systems were less forgiving. I bet people would pay more attention if the browser stopped rendering on JavaScript errors or misformed HTML/CSS. This forgiveness seems to encourage a culture of sloppiness which tends to spread out. I have the displeasure of looking at quite a bit of PHP code. When I point out that they should fix the hundreds of warnings the usual answer is…

This often devolves into extremely fragile systems instead. For instance, let's say you failed to load an image on your web site. Would you rather the web site still work with the image broken or just completely fail? What if that image is a tracking pixel? What if you failed to load some experimental module? Being able to still do something useful in the face of something not going according to plan is essential to…

That's an interesting distinction. I think each resource should be self contained. Malformed HTML? HTML error. Malformed or missing image? Browser displays an image error.

The key here is that the web wasn't designed for engineers but for amateurs to slap something together sloppily in the first place.

As an aside it's curious how ridiculously forgiving HTML and JS are while CSS craps itself on a single missing semicolon. As though it were okay for the thing to be semantically and functionally malformed and malfunctioning... as long as it looks good!

Re: Systems that defy detailed understanding

#38

Post by andai »

twic wrote: post #34
yuliyp wrote: post #23

Earlier quoted context omitted.

This often devolves into extremely fragile systems instead. For instance, let's say you failed to load an image on your web site. Would you rather the web site still work with the image broken or just completely fail? What if that image is a tracking pixel? What if you failed to load some experimental module? Being able to still do something useful in the face of something not going according to plan is essential to…

Systems need to be robust against uncontrollable failures, like a cosmic ray destroying an image as it travels over the internet, because we can never prevent those. But systems should quickly and reliably surface bugs, which are controllable failures. A layer of suffering on top of that simple story is that it's not always clear what is and what is not a controllable failure. Is a logic error in a dependency of some…

> systems should quickly and reliably surface bugs, which are controllable failures

I was thinking, if the error exists between keyboard and chair, I want the strictest failure mode to both catch it and force me to do things right the first time.

But once the thing is up and running, I want it to be as resilient as possible. Resource corrupted? Try again. Still can't load it? At this point, in "release mode" we want a graceful fallback -- also to prevent eventual bit rot. But during development it should be a red flag of the highest order.

Re: Systems that defy detailed understanding

#39

Post by 9wzYQbTYsAIc »

Koshkin wrote: post #32
Ididntdothis wrote: post #22

I often wonder if things would be better if systems were less forgiving. I bet people would pay more attention if the browser stopped rendering on JavaScript errors or misformed HTML/CSS. This forgiveness seems to encourage a culture of sloppiness which tends to spread out. I have the displeasure of looking at quite a bit of PHP code. When I point out that they should fix the hundreds of warnings the usual answer is…

Indeed, less rigidity and higher tolerances lead to reliability - similar to what we do in construction of buildings: a skyscraper would fall one day if it wasn't for its flexibility under effects of elements such as wind.

Interesting related trivia: engineers build safeguards around that flexibility - in the same way that a poorly built bridge will shake itself apart in the wind, a building without adaptive dampening or the right properties of flexibility could shake itself apart in the wind.

Re: Systems that defy detailed understanding

#40

Post by pdr2020 »

Ididntdothis wrote: post #22

I often wonder if things would be better if systems were less forgiving. I bet people would pay more attention if the browser stopped rendering on JavaScript errors or misformed HTML/CSS. This forgiveness seems to encourage a culture of sloppiness which tends to spread out. I have the displeasure of looking at quite a bit of PHP code. When I point out that they should fix the hundreds of warnings the usual answer is…

On a sidenote, I intensely dislike statements like this that hedge their point.
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