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Ask HN: What's your "it's not stupid if it works" story?

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Re: Ask HN: What's your "it's not stupid if it works" story?

#101

Post by whartung »

fxtentacle wrote: post #89

We have a production service running for years that just mmaps an entire SSD and casts the pointer to the desired C++ data structure. That SSD doesn't even have a file system on it, instead it directly stores one monstrous struct array filled with data. There's also no recovery, if the SSD breaks you need to recover all data from a backup. But it works and it's mind-boggingly fast and cheap.

I've always wanted a Smalltalk VM that did this.

Eternally persistent VM, without having to "save". It just "lives". Go ahead, map a 10GB or 100GB file to the VM and go at it. Imagine your entire email history (everyone seems to have large email histories) in the "email array", all as ST objects. Just as an example.

Is that "good"? I dunno. But, simply, there is no impedance mismatch. There's no persistence layer, your entire heap is simply mmap'd into a blob of storage with some lightweight flushing mechanic.

Obviously it's not that simple, there's all sorts of caveats.

It just feels like it should be that simple, and we've had the tech to do this since forever. It doesn't even have to be blistering fast, simply "usable".

Re: Ask HN: What's your "it's not stupid if it works" story?

#103

Post by dharmab »

rented_mule wrote: post #78

15+ years ago, I was working on indexing gigabytes of text on a mobile CPU (before smart phones caused massive investment in such CPUs). Word normalization logic (e.g., sky/skies/sky's -> sky) was very slow, so I used a cache, which sped it up immensely. Conceptually the cache looked like {"sky": "sky", "skies": "sky", "sky's": "sky", "cats": "cat", ...}. I needed cache eviction logic as there was only 1 MB of RAM av…

Similarly, a modder recently found that unrolling loops _hurt_ performance on the N64 because of RAM bus contention: https://www.youtube.com/watch?v=t_rzYnXEQlE

Re: Ask HN: What's your "it's not stupid if it works" story?

#105

Post by Noumenon72 »

jcalvinowens wrote: post #91

I "fixed" an appliance that was nuisance tripping an AFCI breaker by wrapping the power cord one turn through a ferrite choke.

I like how ChatGPT lets you speak efficient jargon while I can read in layman terms. It says an Arc Fault Circuit Interrupter is supposed to detect arcing electrical faults, but some appliances have arcs in their normal operation, causing nuisance trips. A ferrite choke is a ring of magnetic ceramic that is designed to suppress high-frequency electromagnetic interference in electronic circuits. Clever and practical, says ChatGPT.

Re: Ask HN: What's your "it's not stupid if it works" story?

#106

Post by MBCook »

I used to work at a small company. We had a few remote embedded devices that did work and sent data back to the mothership over the internet. Their firmware could be remotely updated, but we were always very careful.

Well one day a mistake was finally made. Some of the devices went into a sort of loop. They’d start running the important process, something would go wrong, and they’d just retry every few minutes.

We caught the issue almost instantly since we were watching the deploy, and were able to stop updates before any other devices picked it up. But those that already got it were down.

We could ask the devices to send us the output of a command remotely, but it was too limited to be able to send back an error log. We didn’t have time to send back like 255 characters at a time or whatever, we needed to get it fixed ASAP.

And that’s when the genius stupid hack was suggested. While we couldn’t send up a full log file, we could certainly send up something the length of a URL. So what if we sent down a little command to stick the log on PasteBin and send up the URL to us?

Worked like a charm. We could identify what was going wrong and fix it in just a few minutes. After some quick (but VERY thorough) testing everything was fixed.

Re: Ask HN: What's your "it's not stupid if it works" story?

#107

Post by gcanyon »

Back in the '90s I consulted at HBO, and they were migrating from MS Mail on Mac servers to MS Exchange on PCs. Problem was that MS Mail on the Mac had no address book export function, and execs often have thousands or even tens of thousands of contacts. The default solution was for personal assistants to copy out the contacts one by one.

So I experimented with screen hotkey tools. I knew about QuicKeys, but its logic and flow control at the time was somewhat limited. Enter which had a full programming language.

I wrote and debugged a tool that:

   1. Listened to its own email box: cole.exporter@hbo.com
   2. You emailed it your password (security? what security?)
   3. Seeing such an email, it logged out of its own email and logged in to yours.
   4. Then it opened your address book and copied out entries one by one. 
   5. It couldn't tell by any other method that it had reached the end of your address book, so if it saw the same contact several times in a row it would stop.
   6. Then it formatted your address book into a CSV for importing to Exchange, and emailed it back to you.
   7. It logged out of your account, and back into its own, and resumed waiting for an incoming email.
This had to work for several thousand employees over a few weeks. I had 4 headless pizza box Macs in my office running this code. Several things could go wrong, since all the code was just assuming that the UI would be the same every time. So while in the "waiting" state I had the Macs "beep" once per minute, and each had a custom beep sound, which was just me saying "one" "two" "three" and "four". So my office had my voice going off an average of once every fifteen seconds for several weeks.

Re: Ask HN: What's your "it's not stupid if it works" story?

#108

Post by jedberg »

rolisz wrote: post #26
cr3ative wrote: post #18

Earlier quoted context omitted.

This reminds me of a service I recently found that was routinely crashing out and being restarted automatically. I fixed the crash, but it turns out it had ALWAYS been crashing on a reliable schedule - and keeping the service alive longer created a plethora of other issues, memory leaks being just one of them. That was a structural crash and I should not have addressed it.

How many memory leaks were discovered only during the winter code freeze, because there were no pushes being done, so no server restarts

At reddit we would randomly select a process to kill every 10 minutes out of the 10 or so on each machine, just so they would all get a restart in case we didn't do a deployment for a few days.

At Amazon they schedule service bounces during code freeze for any service that is known to have memory leaks because it's easier than finding the leak, which isn't usually an issue since it gets deployed so often.

Re: Ask HN: What's your "it's not stupid if it works" story?

#109

Post by teddyh »

leonheld wrote: post #10

`sed` text files as a replacement for templating. In the text file you have something you want to template (or "parametrize") from an outside variable, so you name that something like @@VAR@@ and then you can sed that @@VAR@@ :-)

I think the m4 macro processor might be the more canonical way to do it. Unless you’re writing a shell script, in which case a “here-document” with embedded $VARIABLES is more straightforward.

Re: Ask HN: What's your "it's not stupid if it works" story?

#110

Post by MBCook »

whartung wrote: post #101
fxtentacle wrote: post #89

We have a production service running for years that just mmaps an entire SSD and casts the pointer to the desired C++ data structure. That SSD doesn't even have a file system on it, instead it directly stores one monstrous struct array filled with data. There's also no recovery, if the SSD breaks you need to recover all data from a backup. But it works and it's mind-boggingly fast and cheap.

I've always wanted a Smalltalk VM that did this. Eternally persistent VM, without having to "save". It just "lives". Go ahead, map a 10GB or 100GB file to the VM and go at it. Imagine your entire email history (everyone seems to have large email histories) in the "email array", all as ST objects. Just as an example. Is that "good"? I dunno. But, simply, there is no impedance mismatch. There's no persistence layer, yo…

Isn’t that sort of the original idea for how Forth would work? Everything is just one big memory space and you do whatever you need?

I’m going from very hazy memory here.

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