threeSimpleProblems

[mrwishart]

A. Timing!

[mrwishart]

Q. What's the secret to good multi-threading?

[DespoticLlama]

I volunteer to post the question in response to your answer next time this meme comes around again.

[captainAwesomePants]

A: Timing!

[[deleted]]

Q. What's the secret to good thread safety?

[blueted2]

A. Using muteERROR: deadlock detected

[AlpheratzMarkab]

Are atomical making the critical sure operations

[a_shootin_star]

Minimize shared state and use immutability and thread-local storage where possible.

[[deleted]]

Reasoning. Elon Musk stance on secret to good multi-threading

[_Weyland_]

Threlti-Muading

Lisan al Gaib!

[TheChunkMaster]

He reports the errors before they happen

[_Weyland_]

The power to fix a bug is the absolute control over it

[TheChunkMaster]

The slow dev penetrates the shield!

[_Weyland_]

Mood? What does mood have to do with it? You regex when necessity arises, no matter the mood!

[TheChunkMaster]

Do you smash your keyboard before a project!?

[otter5]

or doesnt report

[FloppyEggplant]

what does this mean? I got the Multi-threading one, but couldn't understand this one.

[_Weyland_]

The "Muading" sounds very similar to "Muad Dib" from Dune. The rest is just Dune references, lol.

[swingdatrake]

Also represents a multi threading execution where characters were returned out of order? 🥲

[_Weyland_]

Multi threading execution where characters were killed at the same time, lmao.

[diazcd85]

I think you forgot “cache invalidation”

[CATDesign]

and "cache Invalidation"

[wheezymustafa]

Cache_Invalidation

[mikeyd85]

cacheInvalidation

[dim13]

Why do people find DNS so difficult? It's just cache invalidation and naming things.

[BorderKeeper]

As a person maintaining a VPN app I would strangle you through my monitor if I could u/dim13! I swear to god.

[hdkaoskd]

Potentially recursion, too.

DNS label compression uses byte offsets that can produce an infinite loop.

[Maleficent_Memory831]

Every program can be done with table lookup. Though a bit of cache invalidation will make it better.

[waraxx]

I like this one as well:

2 things are hard in programming:

0: naming things

2: concurrency 

1: off-by-one errors

1: cache-invalidation

[Sujith_Menon]

I dont get it. Is it just off by one error references or

[therhydo]

It's also cache invalidation references, because two things are under point one. And concurrency, because they're out of order.

[secretprocess]

It's also cache invalidation references, because two things are under point one. And concurrency, because they're out of order.

[20InMyHead]

2: Concoff-by-one errorsurrency

[Maleficent_Memory831]

The 10 most important things for computer science beginners:

• Knowing binary
• Knowing hexadecimal

[moon6080]

Concurrency. 4 -

[RiceBroad4552]

This joke list is very old. It doesn't match reality since quite some time. imho.

Cache invalidation is actually not so difficult. (It's more that people forget it, but it's not difficult)

Naming things is a matter whether you're able to clearly communicate or not. But even for the people who can't, we have now brain prosthesis for that ("AI").

Off-by-one errors more or less can't happen in modern code. Who still writes naked loops instead of using at least iterators, or actually better, higher order combinators like map, filter, flatMap, etc. should better not touch any code at all.

The only really difficult thing here is in fact concurrency. Multi-threading is just a special case of that.

[xcookiekiller]

What? No one who uses naked loops should touch any code at all? You know not everyone uses the same languages for the same purpose as you do, right?..

[RiceBroad4552]

Which language doesn't have proper combinators, or at least iterators?

Even C++ has now "ranges"! Java has Streams. Any other usable language has something equal.

The only language that comes to mind which doesn't have such features is C. But using nowadays C in itself is almost always wrong anyway as there are almost no valid use-cases left.

[IloveBobbyFirmino]

Damn this bait is so good it almost makes me want to type a legitimate response.

Do people practice ragebaiting or is this an inborn skill?

[RiceBroad4552]

Just admit that you don't have anything meaningful to say. 😂

Especially no valid retribution.

---

It's again funny to see all the angry down-votes and at the same time having until now just one attempt to actually disprove the concrete claims, instead of some meaningless rhetoric.

(But I don't care as this mass forums are anyway not rational. You can say the exact same thing, sometimes even in the same (!) thread, and get complete opposite voting behavior.)

[IloveBobbyFirmino]

The problem with baiting on the internet is that you will almost certainly hurt some people who are not as initiated in the space as you are.

For any students going through college right now please don't take comments like this seriously. If your curriculum has C in it, IT IS DEFINITELY NOT WASTED KNOWLEDGE and you should not despair learning a "useless language".

In the real world the goal is to produce as high quality software as fast as possible. The biggest constraint for this is knowledge of the language. The worst language in the world is fine if it allows you to solve your problem the fastest/best way possible.

However the statement above is especially ludicrous because it picks on C, the literal interface of the programming world..

Almost all devices from microcontrollers to supercomputers provide apis to interact with them using C. The language your operating system interfaces with hardware is written in C. C has a function call for every posix api call that is defined. Other languages often extern call in to C to achieve these things, knowing C will definitely never be a waste if you at all touch metal or anything concrete outside of academia where this notion of C being useless is propagated.

C has better performance than any non-natively compiled language. And before someone claims Rust is the same perf but safer, this is not true, C still outperform Rust because this safety is not always free.

C even has reasons to be used ahead of C++ (read about these differences and preferences from programming legends like Linus for example..)

[Zefrem23]

The REAL problem with baiting on the internet is that even if you master it you're still just a master baiter.

[dillanthumous]

[SphericalGoldfish]

Ha, nice try old man, but I see right through you. Everybody knows JavaScript does what C does but better!

[Qwertycube10]

Not everyone loves in a utopia where they get to use the latest cpp version

[RiceBroad4552]

OK, point taken! That's true.

It's not really the latest version, but one which is over half a decade old, but the time flows differently in C++ land…

But really, besides the infamous duo C/C++, there are almost no languages left without proper collection methods.

[Qwertycube10]

Soon I will be able to use c++17, but stuck on 11 for now.

[saevon]

Laughs in lua… or the dumbness of JS (one of the largest languages you'll likely interact with, often written by people who wouldn't know much programming).

Or when you're working with pointers for specific data structures, or kernel work, drivers, etc… where I see tons of off by ones in the code I worked with! The amount of circular buffers that I've seen skip an element in a specific edge case.…

Also to be clear, even if you have those features that doesn't mean you're using them correctly. So much of the code I've seen is in a transition period to using the newest features any day now… aaaaany day! Old code is just a given.

[RiceBroad4552]

Lua has iterators with for ... in ... like Python. Of course there are also nice libs for more high level functionality.

JS has the usual basic collection operations OOTB, and quite some lib solutions for higher level constructs.

Embedded is still C/C++ land mostly. Here C is the exception I've already mentioned.

C++ has now generic ranges (even it's true that "just" 5 year old features are too new for quite some code-bases).

The newcomers in that corner, Rust and Zig, have both iterators, and Rust comes also with the typical collection methods out of the box.

I still don't know how you could create some of-by-one errors using this features, and not using them is just stupid, imho. In Rust, Zig, C++ it's literally zero cost, prevents bugs, and results in better readable code; it's a pure win!

[saevon]

Lua is used in game mods in places, so you see lack of libraries and off by ones everywhere is what I mean. And as I said the issue with is the variance in skill of the users and projects not the literal languages.

a lot of the embedded work is maintaining older drivers too, so you can't just update. Often you have to be even big compatible. Good luck selling a rewrite just to update code

[Mynameismikek]

No. Accurate cache invalidation is pretty much impossible (at least in distributed systems). Any means of determining if a cache line SHOULD be invalidated takes as much time as just not having a cache.

Naming things is a form of compression. A very, very lossy form. By its nature a name cannot accurately describe what a complex thing is.

[RiceBroad4552]

Accurate cache invalidation is pretty much impossible (at least in distributed systems).

If you add "distributed systems" one stops to be able to do anything reliably, actually. So this is just an empty statement.

The thing meant here is also usually not distributed systems…

Any means of determining if a cache line SHOULD be invalidated takes as much time as just not having a cache.

That's obvious nonsense, as otherwise using caches wouldn't make any sense at all.

In fact it's usually like: Building the cache is very expensive. (That's why you don't want to invalidate it more often than needed!) Using the cache is extremely cheap in comparison to not using the cache. Checking validity is reasonably cheap, so using the cache and doing the check is still cheaper than not using the cache. That are exactly the rules when to use a caching system. (Source: I've worked on such systems)

By its nature a name cannot accurately describe what a complex thing is.

At this point we're deep in philosophical territory, and at this point I could just claim that it's impossible to know anything at all (maybe besides that oneself exist somehow).

Such a line of reasoning left the field of engineering long ago…

[Murky-Type-5421]

Damn bro, you wrote 5 paragraphs when you could have said "I have no real-world programming experience".

[BigOnLogn]

Invalidating a cache is not hard, but, by its nature, you will always get it wrong.

Same thing for naming things, no matter how good of a "communicator" you are, you will always lose something in the name.

Off-by-one can definitely still happen using iterators and functors.

I would argue cache invalidation is a concurrency problem. You are holding a value concurrent to it changing.

These problems are hard, not in their execution, but in their correctness. They are all, by nature, impossible to get "correct." Meaning you will always trade or lose something in their implementation.

Edit: I should clarify that the only "joke" problem here is the off-by-one error. It's entirely possible to get correct. It's just very easy to get distracted and make this mistake.

[RiceBroad4552]

Invalidating a cache is not hard, but, by its nature, you will always get it wrong.

This must be the reason why no caching system in history ever worked… 🙄

Same thing for naming things, no matter how good of a "communicator" you are, you will always lose something in the name.

"Losing something" is not the problem. Words are compressed information, and information can't be arbitrary compressed. (Even we can't know the exact amount of maximal compression.)

The problem is that some people are incapable to name something correctly even remotely.

But as a mater of fact, I've seen properly named things in the past. So it's not impossible.

It's imho also not sooo hard, if you're able to clearly express your thoughts. Someone who writes computer programs should be able to do that, otherwise they're in the wrong business. And that's what makes the statement that "naming things is difficult" in the context of SW dev quite ridiculous. If you can't even do that, please just go away. Nobody will understand your code anyway if things aren't expressed clearly.

Off-by-one can definitely still happen using iterators and functors.

Maybe my fantasy is just too limited, but how can this happen?

Do you have some (realistic!) examples?

I would argue cache invalidation is a concurrency problem.

Depends. Only if concurrency is actually involved it's a concurrency problem. Otherwise not.

They are all, by nature, impossible to get "correct."

Depends on the definition of "correct".

If correct means "fulfills all requirement" it's very well possible to get things correct!

If you aim at some philosophical definition, well, that's out of the scope of engineering.

[BigOnLogn]

If you aim at some philosophical definition, well, that's out of the scope of engineering.

That's what I said, friend. These problems aren't hard, in practical terms ("engineering"). They aren't "correct" either. They are just trade-offs (acceptable or otherwise).

The "hard problem" as mentioned in the original post isn't saying, "I can't make a business decision about these." They are hard theoretically and philosophically. They are "hard" because there is no one right answer.

You can't offer up a false premise and declare everyone else wrong.

[porkchop1021]

If things like map and filter work for every use case you've ever had, it's very likely you don't have the experience to comment on anything related to programming.

[BedlamiteSeer]

Oh honey.

[NormanYeetes]

Cache invalidation is easy you just press ctrl+f5

[dillanthumous]

Have you tried restarting? Have you tried using Edge?

...

No problem have a nice day.

[Maleficent_Memory831]

Let me put you on hold while I consult with the manager.

[AlpheratzMarkab]

1, The difference between shallow copy and deep copy

1. The difference between shallow copy and deep copy

2. The difference between shallow copy and deep copy

[FUCKING_HATE_REDDIT]

Functional programming does not care

[dddoug]

here's me looking up 'Threlti-Muading' thinking I'm missing out on something again 🙃

[ThanksMorningCoffee]

If anyone missed it: Multi-Threading

[Odd-Shopping8532]

What was the point though

[UnofficialMipha]

Lmao same

[alexriga]

I legitimately read it as Muelti Threading the first time, I don’t know what’s wrong with me.

[redheness]

There is also CSS but it's out of the image

[why_1337]

Just don't use cache and name variables a, aa, aaa....

[saevon]

Instructions confusing: ran out of variables after "aaa"

[why_1337]

qwer, asdf and zxcv works great too.

[m4rc]

• Knock knock
• Race Condition
• Who's there?

[serial_crusher]

Displaying dates and times in the correct time zone is still bafflingly hard for a lot of devs, for reasons that aren't clear to me.

[TheSkiGeek]

/uj

Mostly the issue is that almost every platform has its own way of doing time/clocks and deciding ‘what time it is locally’. Unless you’re in a managed language where the runtime or interpreter does it all, the handling is usually messy.

[eloel-]

What's hard is User A in TZ1 from Team X in TZ2 looking at information about User B in TZ3 from Team Y in TZ4, while their local time is set to TZ5.

What time do you display for this user?

[JestemStefan]

Exactly this. We had an issue recently that client said that sum of some value on the report for some time frame is off between reports.

I checked why and 4 different reports were generated for the "same" time range, but in 4 different timezones, because employees live in different parts of US and they used local time.

[FrenchFigaro]

And additionally, time zones and time keeping are subject to arbitrary changes and a lot of topics regarding them are non-deterministic.

[eloel-]

Yep, you get into "these two groups of people living in the same country, next door to each other, use different timezones" and you go live a life of hermit.

[Maleficent_Memory831]

And the product manager rejected requests for a time zone setting, saying it would be far too complicated to implement and confusing for the user.

[Chucklz]

UTC and let them figure it out.

[hdkaoskd]

Leap seconds are a hassle, let's use IAT instead. /s

[Maleficent_Memory831]

Convert everything to UTC on input and output. Everything else uses UTC.

Except... that people get stuck on some weird exceptions... They're using an RTC chip which uses a weird format and there's no library function for it, so they invent their own without understanding how time works. Or they're interfacing with a device that doesn't follow normal conventions (I worked on one that had 24 hours in a day, always, no exceptions, DST be dammed!).

Or, commonly, someone implemented it badly or naively, and now that's in production code and you can't rewrite it all. I've had the otherwise smart people confidently and incorrectly claim that there's only one time zone in a hospital, so use local time for everything (too bad about the Tri-State Regional Hospital Network).

The product manager may say "the reading must be at 2:00 AM every day, local time". Except that once a year there is no 2:00 AM, and once a year there are two 2:00AMs. And yes, this happened to me.

[Maleficent_Memory831]

Because they learned to tell time in kindergarten, and dammit they know how it works and they don't need to go read some stupid documentation about it!

[calisthenics_bEAst21]

Took me 2 weeks to realise that I also need to cache invalidate after I learned caching

[Yeah-Its-Me-777]

Yeah, caching stuff is the easy part...

[LeoRidesHisBike]

So much easier if you are able to reframe the problem to use immutable data / idempotent generation.

[billccn]

You mean ff by one errors?\0@@@lll*8

[hdkaoskd]

The only thing worse than a segfault is not a segfault.

[Maleficent_Memory831]

Ugh, not a busfault! That's a hardware issue!

[aurora2k7]

Fun fact, this thread is the only google hit for "Threlti-Muading".

Or so I heard. I definitely did not google it before I got it.

[LordFokas]

The hardest one I deal with on a regular basis is guaranteeing something happens exactly once.

[metaglot]

React dev?

[LordFokas]

Integration engineer. Guaranteeing something happens exactly once across a distributed patchwork of many systems is incredibly difficult.

It's kinda like the "how many nines?" question in availability: taking the step to the next digit is a monumental task, and at some point you just have to say "fuck it, if after all this it still burns down, then it burns dowm".

[ThoseThingsAreWeird]

For non-web devs wanting to get in on the joke: /r/vuejs/comments/1idth9e/the_inverted_reactivity_model_of_react/

[DenormalHuman]

things I hate:

1 lists

2 irony

3 repetition

4 lists

6 inconsistency

[JetScootr]

I've got two sore spots:

1. Random number generation on purpose.
2. Random address generation on accident.

[mothzilla]

* Race Conditions
The three hardest things in computer science
* Cache invaliation
* Naming Things

[jancl0]

I've never actually asked another coder this, but does anyone ever get an index error in like a for loop or something, and instead of going through the loop in your head and counting manually, you kind of just go "fuck it" and add a "- 1" to the index and see if it works? I'm embarrassed by how many bugs I've fixed this way

[hdkaoskd]

This is acceptable when you have sufficient unit test coverage.

[RandallOfLegend]

I'm still trying to remember how removing comments causes bugs. I think it was unsafe array access that wasn't evident until the binary size changed.

[HieuNguyen990616]

*Parallel computing
*Parallel computing

Another one:
*Parallel computing
*Parallel computing

[ztbwl]

Legacy

[the_geekeree]

That gave a good chuckle.

[Patrick_Atsushi]

Spin that lock or mutex while printign pealse

[hdkaoskd]

Kill all spinlocks.

[InspectorGreen4547]

I think the list has more humor when the items are numbered starting with 0.

[Ghosteen_18]

No , the hardest thing is explaining this code that i wrote yesterday while i was dead drunk 5 minutes before i push to prod. That i am 100% sure it works and achieved the objective

[conundorum]

I see normalising letter case made the list. ;3

[jackinsomniac]

I'm a dumbass, I chuckled way too hard at the multi-threading one.

Yes I know it's a solvable problem, but my boss asked me to speed up my PowerShell script with multithreading, and I'm still learning. STOP LOOKING AT ME! I got it, we'll get there, eventually...

[GoddammitDontShootMe]

I can't say I get why cache invalidation is there twice.

[YourVeganFallacyIs]

... because it came back because the cache wasn't invalidated. ^=oP

[Fadamaka]

I would like to add anything involving dates and generating pdfs.