Register allocator.
Ask HN: What's the hardest problem you've ever solved?
61–70 of 124 posts
Re: Ask HN: What's the hardest problem you've ever solved?
#62About 10 years ago I built a Scanning Tunneling Microscope. It took me 2 years to complete it and to get it working.
Wow, that sounds really cool!
What parts did you use (how much was "from scratch")?
Any blog post or article about this? I'd love to read more.
Re: Ask HN: What's the hardest problem you've ever solved?
#63Hardest technical problem would have to be my PhD. I worked out how to apply alias analysis to PHP (previously people had figured out how to do it for the easy subset of PHP - I extended it to the entire language of PHP 5.3 or so). [1]
Along the way I'm pretty sure I also figured out how to build SSA form such that you have your alias analysis results available to be used at SSA construction and therefore redundant computation [2]. I never got to chase that down but it was really interesting.
[1] http://paulbiggar.com/research/#phd-dissertation, esp chapter 6.
Re: Ask HN: What's the hardest problem you've ever solved?
#64I was part of a team that designed and implemented a P2P UDP based video streaming protocol, that receives chunks of a stream simultaneously from up to hundreds of peers. It wasn't a "big problem" per se - I worked on seemingly harder problems before and since - but this one was really hard to get right, it was a very non deterministic beast that was extremely hard to test. I remember lots of times that I secretly felt like we would never get this thing working as well as we wanted, but in the end we did.
I left this company long ago but they appear to be going strong still. http://www.giraffic.com/ . I'm sure they improved on that work a lot since then.
Re: Ask HN: What's the hardest problem you've ever solved?
#65Clearly, when I think about the hardest thing I ever coded, I have the following story in mind.
Back in 2002 I was writing a floppy disk driver for the little OS we were writing with a friend. It turned out finding anything else than very sparse documentation was really hard, plus for some unknown reason the floppy drive behavior seemed to be of non-deterministic nature. Maybe the fact that I was 15 didn't help.
At some point, after many nights spent on debugging it, it just worked. I still don't know why. I never changed any line of the code after that moment, by fear of breaking it.
Re: Ask HN: What's the hardest problem you've ever solved?
#66While I've had some weird technical problems (I've worn a number of hats across Network/System Admin, to both front and back end web Development) the hardest is always the non-technical issues.
A few years ago I was contracting for a company that had a Native American Casino as a client. They wanted to build a gamified app/site to engage their customers more.
The single hardest problem was trying to look at the situation from the players point of view. Gambling like this (slot machines) is inherently an illogical thing to do - they know they're never going to make back the money they put in, but they walk away with a smile night after night.
Trying to rationalise (so we could understand their goals and what they might want out of an app/site targeted at them as players) proved impossible for basically everyone on the team.
Re: Ask HN: What's the hardest problem you've ever solved?
#67I usually find architecture problems to be the hardest to solve. The hardest one I've had to deal with is taking a legacy web application ~3 million lines of code and giving it some form of architecture so the product can have a sustainable future. Some of the issues included inline CSS styles, Core logic written in linear Classic ASP, ASP Web Forms written in a linear fashion and so on. As you can guess, what made it hard was trying to solve these issues without breaking anything, this is an obvious example of why automated testing and code quality are so important.
Re: Ask HN: What's the hardest problem you've ever solved?
#68A simulator gave different results depending on the length of the filename of the executable under test. Only when I ran it on two separate but identical machines with different host names (I used the hostname in the file path to keep a record of where things were run) did I discover the cause of the differences in results I was seeing, which was due to the way that syscalls were handled by the simulator.
Re: Ask HN: What's the hardest problem you've ever solved?
#69Going to list a few interesting problems that were easy to solve but the identification of the issue was hard. * A test suite we wrote for a client's project before a massive refactor was stalling randomly, but would continue when you tried to diagnose the problem. Turns out their user creation code used /dev/random, and the system was running out of entropy and so the code was blocking. Moving the mouse or typing on…
> Turns out their user creation code used /dev/random, and the system was running out of entropy and so the code was blocking. Moving the mouse or typing on the keyboard would add entropy, thus cause the tests to resume.
Funny how this goes completely against the typical operant conditioning a user undergoes when working with computers. Usually if your software hangs up, you want to touch nothing and let it finish. But in this case it's actually additional user activity that's needed.
Re: Ask HN: What's the hardest problem you've ever solved?
#70If you're talking only about coding (and not other life challenges), the hardest problem I've solved so far has been figuring out how to build https://recent.io/ with my co-founder. Recommendation engine, fetchers, iOS app, Android app, etc.
There's a very big difference between concept and working code. :)