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Stratoscope

This of course requires a citation of the old joke...

There are two hard problems in computer science: naming things, cache invalidation, and off by one errors.

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There are three hard problems in CS: naming cache things, invalidation, off by one and concurrency. errors,

I thought off by one always had to go at the end.

I think that’s the joke - that concurrency errors is in the wrong place.

It’s that the “errors” from “off by one errros” comes after concurrency (the hard things being: cache invalidation, off by one errors, naming, and concurrency—not concurrency errors)

can’t tell if meta or whoosh

A thought, reasonable but that how you is fail concurrency. at

I think it’s like those tired old UDP multicast jokes which some people don’t get.

Well they sure beat the TCP joke, don't they?

"Hi, I’d like to hear a TCP joke."

"Hello, would you like to hear a TCP joke?"

"Yes, I’d like to hear a TCP joke."

"OK, I’ll tell you a TCP joke."

"Ok, I will hear a TCP joke."

"Are you ready to hear a TCP joke?"

"Yes, I am ready to hear a TCP joke."

"Ok, I am about to send the TCP joke. It will last 10 seconds, it has two characters, it does not have a setting, it ends with a punchline."

"Ok, I am ready to get your TCP joke that will last 10 seconds, has two characters, does not have an explicit setting, and ends with a punchline."

"I’m sorry, your connection has timed out. Hello, would you like to hear a TCP joke?"

https://www.reddit.com/r/Jokes/comments/2ezdl1/i_told_my_fri...

TCP has only 2 round trips, so more like

> C: I would like to tell a joke

> S: You may tell a joke

> C: We are now exchanging the joke

> C: "Knock knock ..."

What joke?

The joke is that UDP doesn't guarantee packet delivery (or order of arrival).

> What joke?

This is a UDP joke.

I don't care if you get it.

I still didn't get it.

You use UDP (as opposed to TCP) when you want to send data but don't need to wait for any response. A good example is streaming metrics when you can afford to miss some by the metrics aggregator or sending out player location data in a multiplayer game - if you miss the player location update in packet N, you'll just get the update in the N+1 packet or later and update their position at that time. This is totally different than TCP where you want the other server to acknowledge they got the packet else you send it again.

So the joke is a play on words. "You may not get it, the udp packet" (because that is how UDP works by design) and "you may not get it, the joke" (due to being unfamiliar with UDP).

Joke: "I would tell you a UDP joke but you might not get it."

Of course, I might be spoiling the point someone else is making by not posting the joke.

I've heard it:

"I've got a UDP joke for you. You might not get it... but I don't care.".

The nature of UDP

There are two hard problems in CS: cache invalidation, naming things, and cache invalidation.

There is only one hard problem in software engineering: people.

There are four hard problems in CS: naming cache things, invalidation, off by one and concurrency. errors, and memory alloca

There are 5 hard proble… to unlock send 2 BTC to 1lockerA7h……

Something something all problems fixed by blockchain

problems(problems)

There are problems.

It really doesn’t require it, not here anyway where comments are supposed to be substantive.

I hope it doesn’t seem supporting the HN guidelines is, against fun or anything. I think it’d be great to hear at some social get-together or even as part of a tech talk.

One problem with it here is as you can see are long cascading joke reply comments which make it hard for interesting comments to be seen.

And yet I found the parent comment interesting and on topic and yours tangential and pedantic.

Redditors often bemoan how comment threads are ruined by low-effort commenters making low-effort jokes. It's an easy, knee-jerk complaint that ignores the bigger, tougher problem of bad moderation. Subreddits are plagued by bad moderators whereas HN at least has a few good moderators who can regulate the discourse well.

Some commenters can't tell the difference: they think so lowly of their fellow commenters that even one joke is cancer. Quite a silly condescension given that this one "joke" thread is buried towards the middle of the page and is also producing interesting links like https://en.wikipedia.org/wiki/Naming_and_Necessity

I find it interesting that, while accusing commenters about thinking lowly about others and being condescending, you’re actually doing that exact same thing.

My point was that small minds use pedantry to compensate for insecurity. I’m sorry that it hits too close to home.

Actually the reference to the joke about cache invalidation being hard is about something else than the article is actually about: the article is about undesired dirty caches and concurrency, while the original joke is about designing algorithm to invalidate caches.

I see that my citation of that joke was not to your taste. I appreciate the feedback.

HN provides a solution for the long cascading joke thread. To the right of every comment is a [-] link which collapses the entire thread.

Have you watched The Marvelous Mrs. Maisel? I recommend it. There are so many scenes where she or another comedian just bombs. That is part of the life of a comedian, and learning from when you bombed is how you get better at your craft.

Regarding the off by one joke, personally I find it insightful and relevant to the life of a software engineer. Doesn't it get you thinking about all the ways an off by one error can sneak into your code?

Consider your everyday ruler or tape measure. What is the first whole number you see on it? 1, of course. But the ruler doesn't actually start at 1. It starts at 0.

Or consider a graphic system where you describe the coordinates of a rectangle. You may describe these as (left,top)-(right,bottom), or in other words (x1,y1)-(x2,y2).

Now how do you describe a single pixel? Is it (0,0)-(0,0)? That kind of makes sense. Or should you use (0,0)-(1,1) for a single pixel, and (0,0)-(0,0) is an empty rectangle?

These are not easy questions to answer. One of the best explanations I've seen was in Inside Macintosh, written by my friend Caroline Rose.

Here is a discussion with Guido's and Caroline's thoughts on zeroes and ones:

https://news.ycombinator.com/item?id=6602497

Let me leave you with an Amicus Curiae brief filed before the US Supreme Court:

https://www.supremecourt.gov/DocketPDF/22/22-293/242596/2022... [PDF]

The brief begins:

> The Onion is the world’s leading news publication, offering highly acclaimed, universally revered coverage of breaking national, international, and local news events. Rising from its humble beginnings as a print newspaper in 1756, The Onion now enjoys a daily readership of 4.3 trillion and has grown into the single most powerful and influential organization in human history.

It's funny that if you say "cache" invalidation is hard the CPU people will nod, the database people will nod, the CDN people will nod and they will all be thinking of different things.

I had always heard this saying as an undergrad in CS but never understood why names were supposed to be a hard problem until reading about modal logic about a decade later.

https://en.wikipedia.org/wiki/Naming_and_Necessity

The first two are the same problem so this is almost correct.

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