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Drop millions of allocations by using a linked list

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Re: Drop millions of allocations by using a linked list

#61

Post by ryanjshaw »

rfrey wrote: post #51

I'm really surprised by the amount of smugness in the comments here. A bit of good-natured teasing, followed by a wheelbarrow full of "ruby-devs" this and "web-devs" that. Take off your Hats of Superior Coding. Any one of us, regardless of honorific titles, could have made this mistake, and you know it. Being steeped in CS Fundamentals does not immunize you against bugs. Congratulations to tenderlove for finding the…

Is this even a bug or just a case of "in version 0.1 we'll do this quick & dirty", i.e. unaddressed technical debt?

I make a point to keep track of all technical debt in my projects so that I have an easy way to quickly identify opportunities for improvements when there is spare capacity, and also so that technical debt isn't left unaddressed.

Re: Drop millions of allocations by using a linked list

#64

Post by manish_gill »

perdunov wrote: post #6
steipete wrote: post #3

Ruby people discovering algorithms ducks

Really. Every time I whine publicly how web programming people aren't familiar with even basic CS, I get a slap. But really, I should move to web programming. I'll be an expert computer scientist there, probably.

I'm a web dev who has a degree in CS. Do you think I'm a unicorn?

Of course not. Stop generalising.

Re: Drop millions of allocations by using a linked list

#65

Post by FLUX-YOU »

robmccoll wrote: post #35
Swizec wrote: post #19

Earlier quoted context omitted.

I keep repeating myself on Hacker News, but once more, we've found the difference between Software Engineer and Computer Scientist. One makes things work, the other is a mathematician. Why do we keep conflating the two?

You should be careful with the term engineer. By definition, engineering is the application of scientific and mathematical knowledge to solving practical problems. Without knowing and understanding the science and math behind computing and software, one can hardly claim to be a software engineer.

The title is cheap in the US and in some companies (cough) they slap it on every position that directly touches the product.

Re: Drop millions of allocations by using a linked list

#66

Post by herewego »

kaeluka wrote: post #54
rakoo wrote: post #39

Earlier quoted context omitted.

Yes it does: vectors are good for random access, linked-lists are good for doing stuff in the front/back of the list. The performance bug we have here is solved by finding a way to insert stuff at the front/back (and also going through each item in the list); there is no need for random access.

If I remember Bjarne's talk correctly, vectors (in C++) are even fast at inserting because they have densely packed representation which rhymes well with modern computer architecture. Inserting in a linked list is slow, as walking the list to find the element at which to insert will already incur O(N) cache misses, whereas in vectors it's only O(1) cache misses. Moving the elements in the vector one to the right is f…

Yes, but FWIW most linked list implementations have a reference or pointer to the tail, making appends not O(n), but O(1). However, there is a threshold, depending on use case, where a small vector being resized multiple times larger than the original will be faster than many linked list appends. Point being, either can accel depending on use case.

Re: Drop millions of allocations by using a linked list

#67

Post by tobeportable »

mbrock wrote: post #44

Semi-related: does anyone know why installing gems is so ridiculously slow? What is the thing doing? Downloading tarballs, yes, but then? It's a dynamic language; there is no compilation or verification! Why can I install Ruby packages using apt almost immediately, when gem/bundle install takes half a coffee break? I'm growing more impatient with the years. I have measured out my life with slow software. We talk abou…

U can also run with option -j4 to get 4 workers doing the task; u can also add it to your global config : bundle config --global jobs 4

Re: Drop millions of allocations by using a linked list

#68

Post by matthewmacleod »

DiabloD3 wrote: post #62
steipete wrote: post #3

Ruby people discovering algorithms ducks

Not sure why parent is getting downvoted, there is a serious problem in the Ruby community that very few of them have read GoF, TAoCP, and/or K&R.

Because it's smug and adds nothing to the conversation.

I don't see any evidence that the Ruby community suffers more than any other development community from this sort of thing — that is, the ones where high performance is not the biggest concern, of course.

Re: Drop millions of allocations by using a linked list

#69

Post by matthewmacleod »

perdunov wrote: post #6
steipete wrote: post #3

Ruby people discovering algorithms ducks

Really. Every time I whine publicly how web programming people aren't familiar with even basic CS, I get a slap. But really, I should move to web programming. I'll be an expert computer scientist there, probably.

Good, you deserve a slap for being self-satisfied about it. There are loads of fully competent and skilled web developers out there with great, in-depth CS knowledge, and publicly berating them achieves nothing.

Web development is interesting, because it tends to mix in people from a lot of different backgrounds — in particular, some of them come through the design side, and move down the stack. That's good, because it demonstrates the accessibility and flexibility of the stack; it's bad because it can result in suboptimal solutions to common problems.

Re: Drop millions of allocations by using a linked list

#70

Post by mkopinsky »

ryanjshaw wrote: post #61
rfrey wrote: post #51

I'm really surprised by the amount of smugness in the comments here. A bit of good-natured teasing, followed by a wheelbarrow full of "ruby-devs" this and "web-devs" that. Take off your Hats of Superior Coding. Any one of us, regardless of honorific titles, could have made this mistake, and you know it. Being steeped in CS Fundamentals does not immunize you against bugs. Congratulations to tenderlove for finding the…

Is this even a bug or just a case of "in version 0.1 we'll do this quick & dirty", i.e. unaddressed technical debt? I make a point to keep track of all technical debt in my projects so that I have an easy way to quickly identify opportunities for improvements when there is spare capacity, and also so that technical debt isn't left unaddressed.

How do you keep track of the technical debt? Ticket system?
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