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Ask HN: What rabbit hole(s) did you dive into recently?

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Re: Ask HN: What rabbit hole(s) did you dive into recently?

#271

Post by sparkie »

perihelions wrote: post #269
sparkie wrote: post #267

Earlier quoted context omitted.

> The worst offender (so far) is the JBIG2 format (several major libraries, including jbig2dec), a very popular format that gets EXTREMELY high compression ratios on bilevel images of types typical to scanned pdfs. But: it's also a format that's pretty slow to decompress—not something you want in a UI loop, like a PDF reader is! And, there's no way around that—if you look at the hot loop, which is arithmetic coding,…

- "If my observations are correct, each segment has its own arithmetic decoder state, and thus can be decoded in its own thread." Yeah, but real-world PDF JBIG2's seem to usually have one segment! One of the first things I checked—they wouldn't have made it that easy, the world's too cruel. It's sort of a generic problem with compression formats—lots of files could easily be multiple segments that decompress in paral…

Yikes! Doesn't seem like there's anything that can be done to solve that then.

I guess the only way to tackle it would be to target the popular software or libraries for producing PDFs to begin with and try to upstream parallel encoding into them.

Or is it possible to "convert" existing PDFs from single-segment to multi-segment PDFs, to make for faster reading on existing software?

Re: Ask HN: What rabbit hole(s) did you dive into recently?

#272

Post by rramadass »

Formal Methods; and i don't think i am going to get out of this rabbit hole anytime soon in the future.

More than just using some formal language/tool i had wanted to learn about the Mathematics/Ideas behind formal methods and how they are embodied in TLA/Z language/B method/etc. After a survey of available books i zeroed in on Understanding Formal Methods by Jean François Monin hoping to get an overall idea of how everything comes together. But what i got was a fire-hose/mishmash of so many different sub-fields/notations/abstractions used in the field that it is quite a struggle to get a good grasp on anything. The author's style of writing is obtuse/challenging and the contents are more of a survey/introduction than detailed explanations.

The result is that i am now interested in figuring out a whole lot of mathematical/logical sub-fields which i suspect is going to occupy a lot of my time in the future.

Re: Ask HN: What rabbit hole(s) did you dive into recently?

#274

Post by qup »

batch12 wrote: post #90

I've been researching and planting fruit trees and edible plants. Looking at paw paws, peaches, pears, berries, persimmons and tea bushes.

I'm in a paw paw/persimmon zone, and figs grow nicely. One of the lowest-maintenance trees that don't have much insect pressure. I thought they were notably absent from your list. The variety I chose tastes much like a peach.

Re: Ask HN: What rabbit hole(s) did you dive into recently?

#275

Post by golson_kindmind »

Bottle digging, i.e. looking for and collecting old bottles, typically buried or submerged.

Wife and I live on a floating house in Oregon outside of Portland. Taking my paddle board to various beaches on the river to pick up trash has become a beloved hobby of mine. Fantastic way to get exercise, get out in nature, and clean up my community.

I kept finding old, antique bottles during outings: Coke bottles from the 40s and 50s, little medicine bottles from who knows when, old beer bottles from brands no longer in business. I eventually learned that there's a whole hobby around this called "bottle digging", even an active subreddit (r/bottledigging).

I've since bought a nice snorkel and mask and have been diving for old bottles on clear days, when river visibility allows it. Thinking about taking it to the next level and getting scuba certified.

If you like finding things, you might like bottle digging.

Re: Ask HN: What rabbit hole(s) did you dive into recently?

#276

Post by perihelions »

sparkie wrote: post #271
perihelions wrote: post #269

Earlier quoted context omitted.

- "If my observations are correct, each segment has its own arithmetic decoder state, and thus can be decoded in its own thread." Yeah, but real-world PDF JBIG2's seem to usually have one segment! One of the first things I checked—they wouldn't have made it that easy, the world's too cruel. It's sort of a generic problem with compression formats—lots of files could easily be multiple segments that decompress in paral…

Yikes! Doesn't seem like there's anything that can be done to solve that then. I guess the only way to tackle it would be to target the popular software or libraries for producing PDFs to begin with and try to upstream parallel encoding into them. Or is it possible to "convert" existing PDFs from single-segment to multi-segment PDFs, to make for faster reading on existing software?

Conversion's a very good solution for files you're storing locally! I'm working on polishing a script workflow to implement this—I haven't figured out which format to store things into yet. I don't consider it a full solution to the problem—more of a bandaid/workaround.

The downside is that any PDF conversion is a long-running batch job, one that probably shouldn't be part of any UX sequence—it's way too slow.

Emacs' PDF reader does something like this: when it loads a pdf, its default behavior is to start a background script that converts every page into a PNG, which decodes much more quickly than typical PDF formats. (You can start reading the PDF right away, and the end of the conversion, it becomes more responsive). I think it's a questionable design choice: it's a high-CPU task during a UI interaction, and potentially a long-running one, for a large PDF. (This is why I was profiling libpng, incidentally).

https://www.gnu.org/software/emacs/manual/html_node/emacs/Do...

Re: Ask HN: What rabbit hole(s) did you dive into recently?

#277

Post by mikewarot »

golson_kindmind wrote: post #275

Bottle digging, i.e. looking for and collecting old bottles, typically buried or submerged. Wife and I live on a floating house in Oregon outside of Portland. Taking my paddle board to various beaches on the river to pick up trash has become a beloved hobby of mine. Fantastic way to get exercise, get out in nature, and clean up my community. I kept finding old, antique bottles during outings: Coke bottles from the 40…

My dad and I did that when I was a kid... we were always in search of the Ruby Red beer bottles. We also looked for insulators on the ground near the telephone poles next to old railroads.

We frequented a subdivision that was being built on land that was a former city dump.

Re: Ask HN: What rabbit hole(s) did you dive into recently?

#278

Post by steve_adams_86 »

markdown wrote: post #233
steve_adams_86 wrote: post #137

I’ve fallen into the plant tissue culturing rabbit hole. I was selling excess trimmings of aquarium plants locally on Facebook marketplace and made a surprising amount of money, and my kids really enjoyed it (they got a cut for helping me out). I thought hmm, this could be a great excuse to make a little business around this, teach them some skills, get them thinking more constructively and feeling a sense of agency…

Do you have a biology/botany/lab tech background? I've always really wanted to get into this but really don't know where to start. Also, "Murashige and Skoog" is such a silly name; I love it.

Ha, I love that name too.

I have a background in absolutely nothing. Anyone can do this stuff.

I mentioned in another comment, the book “Plants from Test Tubes: An Introduction to Micro-Propagation” was incredibly helpful to me. You can get a cursory understanding of things from YouTube or similar, but the book does a great job of explaining what you’re actually doing, how, and why.

A good place to start is prepping some media and containers, collecting some plant tissues, sterilizing it, and dropping it into the media in the container! I know each step here is a subject within itself, but it really is this simple when you zoom out a bit. If you aren’t sure about how to make MS media, start with pre-made options from a company like Plant Cell Technologies. You can use glass jars with autoclaveable plastic lids as the containers. You can use a pressure cooker as your autoclave. Collecting the plant material can be simple or extremely difficult (collecting meristem material can be excruciating if you haven’t worked under a microscope before), and it’s fine to start simple (just use a piece of a leaf). You’ll want a flow hood or still air box, and you can make these for peanuts or buy small solutions for pretty reasonable prices.

As someone once told me: There’s nothin to do but to do it

Re: Ask HN: What rabbit hole(s) did you dive into recently?

#279

Post by TheBozzCL »

I deep-dove into the identity of a spammer. They were sending me the crappiest, absolutely lowest-denominator hodge-podge of spam. Fly repellent, ultrasonic dog whistles, knives. It all seemed like legit businesses, so it was just some marketing firm that bought an email list somewhere.

Whenever I get spammed, I check the email headers. Turns out they were using an email with the owner’s initials in the unsubscribe header. From it, I was able to easily guess their actual name. I found them on LinkedIn! I used that, plus the list of all the domains they used for marketing and sending mails, to build a pretty comprehensive map of their operations.

I thought for a while about what I could do with this info… but in the end, reporting them to my country’s consumer rights authority for spam did the trick. No reason to get in trouble myself, as fun as it could be.

So the lesson is: look at email headers! There’s fun stuff in there!

Re: Ask HN: What rabbit hole(s) did you dive into recently?

#280

Post by swapsCAPS »

Oof, Pulumi here. A module was wrapping a Terraform module which wraps a REST client which wraps the provider’s API. Errors only came forward during a `pulumi up` instead of being caught during a `preview`. Fun times digging through those multiple layers of abstractions
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