7 ms·

Yes, but it's unlikely that someone asking "is it faster to concatenate strings in C# using the + operator or StringBuilder" on StackOverflow is someone that is

by grokys 12y ago

Yes, but it's unlikely that someone asking "is it faster to concatenate strings in C# using the + operator or StringBuilder" on StackOverflow is someone that is writing a low-level database engine like SQLite. In my (totally anecdotal) experience the people who are more concerned about performance are beginners, because that is something that they can grasp, and this is where the "don't prematurely optimize" people are coming from. Obviously someone who is writing a low-level database engine knows that performance matters, and likewise, is likely to be running benchmarks rather than asking vague questions on SO.

zamalek 12y ago
Indeed. However, keep in mind that as this beginner "ramps up" to the knowledge level of someone who is working on a SQL database he will need a source to find out where costs lie. He's done some profiling, finds an expensive method with massive amounts of string concats, heads to Google and all he can find is "don't prematurely optimize." You can supplement an answer with "don't prematurely optimize," but the presumption that premature optimization is occurring is a premature assumption. He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever. ~ Chinese Proverb I would work with beginners that are not fools, than experts who are.
- marcosdumay 12y ago
  Nope, if he got to that level, he'll know that the only way to really know it is testing. He may still ask why one is slower than the other (if it is, I don't know that), but that's a completely different question that in most contexts will get a nice answer.
  - bunderbunder 12y ago
    Suppose, for a moment, that our hero is seeing this situation for the first time and doesn't know what the alternatives are. Tests that don't cover the best option can't possibly identify the best option. So if you want to do a really good test, going somewhere to ask, "What else should I try?" is hardly an asinine course of action. On the contrary, if our hero is new to this stuff, or is new to the platform in question, or anything like that, then asking others for advice should probably qualify as due diligence.
- sosborn 12y ago
  > He's done some profiling In my experience on Stack Overflow, the people getting hit with accusations of "premature optimization" have not gone this far.
bunderbunder 12y ago
And that's decent advice in response to the "is it faster to concatenate strings in C# using the + operator or StringBuilder" questions. But I've also asked Stack Overflow questions that drowned under a tsunami of premature optimization tut-tutting from people who I suspect didn't even fully understand the question, and then sighed and proceeded to take a couple days to figure it out myself and improve application performance in a critical section by 50%. Which is fine, but once upon a time I thought Stack Overflow might be a resource where people might occasionally save me a bunch of time by saying, "Hey, don't waste your time, I've been there and it's a blind alley." I think part of what's going on there is that SO's gamification can create some kind of perverse incentives for answerers. If you want to get the upvotes, you have two good courses of action: You can either already have 5 digits' worth of karma, or you can answer first. The first option isn't available to the vast majority of SO users, so most go with the latter one. This drives down the quality of answers. It also creates perverse incentives for behaviors such as users getting in a quick low-quality response that's just good enough to get a few upvotes from people who already understand what you're talking about, and then (maybe) following it up with an edit that provides a high-quality response that would be useful to the asker.
- zamalek 12y ago
  It helps to preempt the typical response. If I post a question that's "premature optimization bait" I end it with: > I'm optimizing this due to profiler results. You'd be surprised how many people still question whether I'm prematurely optimizing in the comments, but the actual answers tend to be more helpful.
  - dragonwriter 12y ago
    Have you tried something more along the lines of: I'm trying to do X. Currently, I'm using Y mechanism, and it produces correct results. However, the performance sucks -- profiling shows me this is a big time sink in my program. So... (actual question.) It may help with kneejerk "premature optimization" if the profiler results are mentioned before the request about how to optimize (at least, it should to the extent that the problem is people stopping reading because they see the optimization request so that they never read the comment about profiler results.)
nitrogen 12y ago
It's not a completely useless question. I wrote an API data validation gem for Ruby that needs to be as unobtrusive as possible, so it needs to be fast. I found that building strings by interpolation (e.g. "#{str1}#{str2}") is quite a bit faster than addition (e.g. str1 + str2).
teyfille 12y ago
To be fair, I once fixed a java application that completely crashed due to using string concatenation for data export, rather than a StringBuffer. It does matter sometimes even in workaday applications.

by grokys 12y ago

zamalek 12y ago

Indeed. However, keep in mind that as this beginner "ramps up" to the knowledge level of someone who is working on a SQL database he will need a source to find out where costs lie. He's done some profiling, finds an expensive method with massive amounts of string concats, heads to Google and all he can find is "don't prematurely optimize." You can supplement an answer with "don't prematurely optimize," but the presumption that premature optimization is occurring is a premature assumption. He who asks a question is a fool for five minutes; he who does not ask a question remains a fool forever. ~ Chinese Proverb I would work with beginners that are not fools, than experts who are.

marcosdumay 12y ago
Nope, if he got to that level, he'll know that the only way to really know it is testing. He may still ask why one is slower than the other (if it is, I don't know that), but that's a completely different question that in most contexts will get a nice answer.
- bunderbunder 12y ago
  Suppose, for a moment, that our hero is seeing this situation for the first time and doesn't know what the alternatives are. Tests that don't cover the best option can't possibly identify the best option. So if you want to do a really good test, going somewhere to ask, "What else should I try?" is hardly an asinine course of action. On the contrary, if our hero is new to this stuff, or is new to the platform in question, or anything like that, then asking others for advice should probably qualify as due diligence.
sosborn 12y ago
> He's done some profiling In my experience on Stack Overflow, the people getting hit with accusations of "premature optimization" have not gone this far.

bunderbunder 12y ago

And that's decent advice in response to the "is it faster to concatenate strings in C# using the + operator or StringBuilder" questions. But I've also asked Stack Overflow questions that drowned under a tsunami of premature optimization tut-tutting from people who I suspect didn't even fully understand the question, and then sighed and proceeded to take a couple days to figure it out myself and improve application performance in a critical section by 50%. Which is fine, but once upon a time I thought Stack Overflow might be a resource where people might occasionally save me a bunch of time by saying, "Hey, don't waste your time, I've been there and it's a blind alley." I think part of what's going on there is that SO's gamification can create some kind of perverse incentives for answerers. If you want to get the upvotes, you have two good courses of action: You can either already have 5 digits' worth of karma, or you can answer first. The first option isn't available to the vast majority of SO users, so most go with the latter one. This drives down the quality of answers. It also creates perverse incentives for behaviors such as users getting in a quick low-quality response that's just good enough to get a few upvotes from people who already understand what you're talking about, and then (maybe) following it up with an edit that provides a high-quality response that would be useful to the asker.

zamalek 12y ago
It helps to preempt the typical response. If I post a question that's "premature optimization bait" I end it with: > I'm optimizing this due to profiler results. You'd be surprised how many people still question whether I'm prematurely optimizing in the comments, but the actual answers tend to be more helpful.
- dragonwriter 12y ago
  Have you tried something more along the lines of: I'm trying to do X. Currently, I'm using Y mechanism, and it produces correct results. However, the performance sucks -- profiling shows me this is a big time sink in my program. So... (actual question.) It may help with kneejerk "premature optimization" if the profiler results are mentioned before the request about how to optimize (at least, it should to the extent that the problem is people stopping reading because they see the optimization request so that they never read the comment about profiler results.)

nitrogen 12y ago

It's not a completely useless question. I wrote an API data validation gem for Ruby that needs to be as unobtrusive as possible, so it needs to be fast. I found that building strings by interpolation (e.g. "#{str1}#{str2}") is quite a bit faster than addition (e.g. str1 + str2).

teyfille 12y ago

To be fair, I once fixed a java application that completely crashed due to using string concatenation for data export, rather than a StringBuffer. It does matter sometimes even in workaday applications.