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New Grad vs. Senior Dev

ericlippert.com

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Re: New Grad vs. Senior Dev

#31

Post by TeMPOraL »

samfisher83 wrote: post #15
dimtion wrote: post #7

I find that the biggest misunderstanding happens because "new grads" (and I happen to be one) confuse _asymptotic complexity_ with actual complexity. I'm not sure sure why, but CS courses and interview questions mostly focus on _asymptotic complexity_ and usually forget to take into consideration the complexity for "little values of n". And funnily enough, in real life n never goes to infinity! In a strict sense big…

When you do big O analysis you get best case, worst case, and average case. You have to do some thinking about the structure of you data when doing big O analysis.

It's not that. Something not properly covered in CS courses is that very often, performance is dominated by things that are not evaluated as a part of big O analysis. Like, memory allocations, cache friendliness, and other constant factors.

For example, according to the theory, a hash table is much better suited for key lookup and random additions than a vector. In practice, if you're storing a couple hundred elements, a flat array (with objects stored directly) will be faster because of data locality. If your problems are mostly "do a lot of small N ops" and not "do some large N ops", then big O analysis isn't all that useful anymore.

Re: New Grad vs. Senior Dev

#32

Post by justinmeiners »

dimtion wrote: post #7

I find that the biggest misunderstanding happens because "new grads" (and I happen to be one) confuse _asymptotic complexity_ with actual complexity. I'm not sure sure why, but CS courses and interview questions mostly focus on _asymptotic complexity_ and usually forget to take into consideration the complexity for "little values of n". And funnily enough, in real life n never goes to infinity! In a strict sense big…

I regularly see people make this mistake and don't grasp it after correction.

You could make a hash table with a constant time lookup, but the hash takes 1 hour. Big oh only tells you how it scales, not it's performance (runtime).

Re: New Grad vs. Senior Dev

#33

Post by saagarjha »

By the way, here’s an anecdote for the flip side: at one of my internships I was working on a tool to process large log files, and by careful application of Aho-Corasick I was able to make it about 50 times faster on the dataset we were dealing with, which made using the tool change from “let’s go grab lunch while this finishes” to “let’s stream the logs through this live”. Sometimes you do know how to make things faster: just make sure to test them before you do, and asking why something is a certain way is always a good thing to do before proclaiming it’s broken.

Re: New Grad vs. Senior Dev

#34

Post by vvanders »

dimtion wrote: post #7

I find that the biggest misunderstanding happens because "new grads" (and I happen to be one) confuse _asymptotic complexity_ with actual complexity. I'm not sure sure why, but CS courses and interview questions mostly focus on _asymptotic complexity_ and usually forget to take into consideration the complexity for "little values of n". And funnily enough, in real life n never goes to infinity! In a strict sense big…

Yup, linear data reads are easily 10-30x faster than random thanks to cache miss penalty staying static since the 90s.

If you want to see real-world DDR speeds figure out what algorithms do linear reads.

Re: New Grad vs. Senior Dev

#35

Post by TeMPOraL »

justinmeiners wrote: post #32
dimtion wrote: post #7

I find that the biggest misunderstanding happens because "new grads" (and I happen to be one) confuse _asymptotic complexity_ with actual complexity. I'm not sure sure why, but CS courses and interview questions mostly focus on _asymptotic complexity_ and usually forget to take into consideration the complexity for "little values of n". And funnily enough, in real life n never goes to infinity! In a strict sense big…

I regularly see people make this mistake and don't grasp it after correction. You could make a hash table with a constant time lookup, but the hash takes 1 hour. Big oh only tells you how it scales, not it's performance (runtime).

It's not even that. You could have a normal hash table with a decent hashing function, and you'll still get beaten by a flat array for small n (hundreds, low thousands), because the array is contiguous in memory - so operations like search or moving stuff around after addition make extremely good use of CPU's cache.

Re: New Grad vs. Senior Dev

#36

Post by daxfohl »

As a senior dev, I wish that I could say I always knew more than my interns, and that all the code that's there is because it was carefully planned to be that way.

But more often than not, I don't, and it's not.

My take on it is that for the most part senior devs are a lot more paranoid on breaking things and don't want to make code changes unless enough people are asking for it and it'll make a notable difference. Even making things strictly faster can break users if they depend on the algorithm being slow (an extreme edge case that you'd usually say is the user's fault anyway, but could nonetheless be relevant in things like optimizing away a spin-wait).

Re: New Grad vs. Senior Dev

#37

Post by saagarjha »

chiefalchemist wrote: post #8
gen220 wrote: post #4

Earlier quoted context omitted.

Putting it another way, knowledge with the bare minimum experience required to be effective is very sharp, and that sharpness is sometimes what’s required to cut through old, retrospectively “wrong” ways of doing things. I don’t disagree with what you’ve said, I think we all have met plenty of people fitting your description, I just mean to say there’s another side of the coin. As food for thought, much (not all) of…

The New Grad had knowledge. The Senior Dev had Understanding. Understanding > Knowledge It's that simple.

Not always.

Re: New Grad vs. Senior Dev

#38

Post by on3 »

TeMPOraL wrote: post #11

Oh god. That meme. I've seen it a day or two ago. Can't find the picture anywhere now (I've seen it in some group chat). Anyway, beyond the words quoted at the beginning of this article, the meme's "nested loops go brrr" had a picture of a triple-nested loop using Active Record to do some simple database operations. To which the correct response is: "it's a 'senior developer' in an industry where you get called a 'se…

Found it: https://i.redd.it/lmrf72ko0ro41.png

Re: New Grad vs. Senior Dev

#39

Post by TeMPOraL »

on3 wrote: post #38
TeMPOraL wrote: post #11

Oh god. That meme. I've seen it a day or two ago. Can't find the picture anywhere now (I've seen it in some group chat). Anyway, beyond the words quoted at the beginning of this article, the meme's "nested loops go brrr" had a picture of a triple-nested loop using Active Record to do some simple database operations. To which the correct response is: "it's a 'senior developer' in an industry where you get called a 'se…

Found it: https://i.redd.it/lmrf72ko0ro41.png

That's it. Thanks!

Re: New Grad vs. Senior Dev

#40

Post by philipov »

chiefalchemist wrote: post #8
gen220 wrote: post #4

Earlier quoted context omitted.

Putting it another way, knowledge with the bare minimum experience required to be effective is very sharp, and that sharpness is sometimes what’s required to cut through old, retrospectively “wrong” ways of doing things. I don’t disagree with what you’ve said, I think we all have met plenty of people fitting your description, I just mean to say there’s another side of the coin. As food for thought, much (not all) of…

The New Grad had knowledge. The Senior Dev had Understanding. Understanding > Knowledge It's that simple.

More like, The New Grad has Ideals. The Senior Dev had Deadlines.

Deadlines > Ideals.

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