4 ms·

> if you are writing such systems (in either language) you are very likely to spend quite a lot of time in 'unsafe' land. I don't think that's necessarily true

by enneff 12y ago

> if you are writing such systems (in either language) you are very likely to spend quite a lot of time in 'unsafe' land. I don't think that's necessarily true. Go does a much better job than Java at letting you manage your allocations and re-use memory. You can write tight, performance-critical code in Go without resorting to 'unsafe'; it just requires care, as it does in any language.

tylertreat 12y ago
I don't know if I completely agree with this. To write truly performance-critical Go, you end up throwing away many of the language's qualities. Channels are slow, defers add overhead, interfaces add overhead (e.g. I2T), etc. Don't get me wrong, I like Go, but in my (and others I work with) experience, it's not the right choice for performance-critical systems.
- enneff 12y ago
  I disagree with "channels are slow". They may be faster than you think. Defers needn't add as much overhead as they do today; this can be fixed. I think it really depends on your definition of "performance-critical". I agree Go isn't suitable for all performance-critical tasks, but it covers a vast swathe of them quite comfortably.
  - eternalban 12y ago
    > this can be fixed. I believe this and am counting on it. Go2.0 and beyond should be a solid choice. You should also note that it is entirely understood that more mature tech e.g. JVM have had the benefit of multibillion Dollar investment by SUN, IBM, Oracle, etc. I feel it is regrettable that (imo valid and reasonable) criticism of what is currently not up to par with this tech always seemingly requires a disclaimer that "I love Go". I have been using this language since the day it was released. I know it fairly well. I like it. But excessive hype and sensitivity around it is frankly somewhat irritating. peace out and happy v. day Go <3
    - enneff 12y ago
      Valentines day was yesterday for me. You wouldn't see me spending my time responding here if it were today!
- eternalban 12y ago
  Not an uncommon view: https://twitter.com/kellabyte/status/564531804837654528 https://twitter.com/kellabyte/status/564531804837654528 (That's not me, to be clear.) We all like Go. Just wish we could discuss these matters without unduly raising temperatures. "It's just code".
  - twotwotwo 12y ago
    Sommers is an absolute beast, does totally astounding work and is an asset to the community. But even when we say "performance-critical" most of us don't mean getting 3M req/sec from one box like she did w/Haywire (https://twitter.com/kellabyte/status/547063455048404992 https://twitter.com/kellabyte/status/547063455048404992). In other words, pushing the hardware absolutely to its limits is another game (Sommers' game :) ) from simply getting a tricky part of your app performing at the level you need. And, confusingly, "high-performance" or "performance-critical" are terms you might use to describe either task. For context, the person whose presentation triggered Kelly's comment, MIT scholar Neha Narula, was experimenting with an 80 core machine, and she replied "it's kind of amazing I could push Go that far," and "to be fair they weren't really optimizing for my use case :)" -- her whole presentation is on YouTube at https://www.youtube.com/watch?v=Mbg1COjhsJU https://www.youtube.com/watch?v=Mbg1COjhsJU (some wild stuff--she got improvements for >48-core machines pushed into the Go GC) and those replies I quoted are at https://twitter.com/neha/status/564569903219634176 https://twitter.com/neha/status/564569903219634176 .
    - danieldk 12y ago
      But even when we say "performance-critical" most of us don't mean getting 3M req/sec from one box like she did w/Haywire We are not all writing web apps. Some of use are in machine learning, NLP, signal processing, etc. where squeezing out as much performance as possible does matter. In those fields Go is still weak. No autovectorization, no OpenMP, no direct CUDA integration, GC overhead, etc. Luckily, this can often be worked around since cgo is so good. One can write performance-intensive parts in C or C++, compile with the latest gcc or clang and link it with the Go code to drive it. This is often an understated advantage of Go compared to Java, where JNI calls are expensive. But the Go camp always advocate for porting everything to Go (because fast compile times).
- twotwotwo 12y ago
  I mean, Go is (or was) in the loop whenever YouTube hit its MySQL clusters (vitess) and on on the server providing downloads of Chrome and so forth (dl.google.com). CloudFlare has it sitting in the middle of every request for some sites (in the form of Railgun, their delta compression for pages). I'm not exactly a perf ninja and got some Go code packing Wikipedia history dumps at >100 MB/s. Dropbox uses Go for, their words, "our performance-critical backends" (https://blogs.dropbox.com/tech/2014/07/open-sourcing-our-go-libraries/ https://blogs.dropbox.com/tech/2014/07/open-sourcing-our-go-...). So folks manage to heavy lifting with it. I see "I couldn't possibly use X for performance reasons" here a lot, as an almost immediate response about a wide range of different tools, and two things come up in my mind: 1) you can always set the standard arbitrarily high. If you're doing AAA shoot-'em-up games or something, yes, use something else. 2) you're often not as good at tools that're new or different. It's possible you could go further with just a few more tricks about profiling or using free pools or whatever, or a little more info about how your code executes or what the runtime does. FWIW, if you hit a specific wall that's a problem for your app, folks on golang-nuts (or StackOverflow, where I've hung out sometimes) are often happy to try and help. Hope this is more helpful than fussy. Mostly just don't want folks to be discouraged into thinking certain things are impossible when in some cases they're really being done in production out there.
  - coldtea 12y ago
    >I mean, Go is (or was) in the loop whenever YouTube hit its MySQL clusters (vitess) and on on the server providing downloads of Chrome and so forth (dl.google.com). Not as impressive as it sounds. Most of it is cached in memory anyway...
  - tylertreat 12y ago
    Agreed with setting the standard arbitrarily high. It depends on what problem you're trying to solve—just like deciding when to use any other tool. Context matters. Where I work, we've been trying to build some super-fast systems and things like the GC and even calling interface methods matter. We open sourced some data structures that show just how optimized we're trying to get (https://github.com/Workiva/go-datastructures https://github.com/Workiva/go-datastructures), but in hindsight, Go might not have been the right tool for the problem.
eropple 12y ago
I don't believe that this is true. You use the exact same patterns and tricks in both for perf-critical code: off-GC primitives and object pools rule the day. What are you considering a "much better" option available in Go? (I considered stack-allocated structs in Go, but honestly that doesn't strike me as a particularly major thing; it may be slightly more terse, but fundamentally the same behavior.)
- enneff 12y ago
  Values ("off-GC primitives?") are first class-citizens in Go. Stack-allocated structs have much more value than you think.
  - eropple 12y ago
    More value than I think? I'm pretty sure that I know exactly their value. I'll maintain that stack-allocated structs are a nice-to-have on top of the sort of stack-allocated primitives that Java provides; I'd like to have those structs as a convenience when I write Java, which is why I alluded to terseness in my prior post. But there's very little (or should be, I suppose, depending on implementation) performance difference to speak of between a struct and parallel declaration of the same values.
    - enneff 12y ago
      You said: > I considered stack-allocated structs in Go, but honestly that doesn't strike me as a particularly major thing; But for me they're one of the major ways in which I control memory use in Go programs. So, yeah, I think you underestimate them. No condescension implied. Apologies if it came across that way. I think we probably agree more than we disagree.
      - eropple 12y ago
        Yeah, I edited it out because after I took a breath I figured you didn't mean it that way. =) Hugs all around. But I really don't think it's a major thing, because there's no meaningful difference, in terms of performance, between "struct { int x; int y; } A" and "int Ax; int Ay;". I'm suspicious of claims that Go, as fundamentally a not that different language to a JVM language, is going to yield significant performance benefits. I'm not saying they aren't a nice convenience (value types are one of the things I love about C# when I'm writing code under MonoGame), I'm saying that I can't think of a reasonable way, barring bugs or short-sighted implementations, that they made for faster code.

by enneff 12y ago

tylertreat 12y ago

I don't know if I completely agree with this. To write truly performance-critical Go, you end up throwing away many of the language's qualities. Channels are slow, defers add overhead, interfaces add overhead (e.g. I2T), etc. Don't get me wrong, I like Go, but in my (and others I work with) experience, it's not the right choice for performance-critical systems.

enneff 12y ago
I disagree with "channels are slow". They may be faster than you think. Defers needn't add as much overhead as they do today; this can be fixed. I think it really depends on your definition of "performance-critical". I agree Go isn't suitable for all performance-critical tasks, but it covers a vast swathe of them quite comfortably.
- eternalban 12y ago
  > this can be fixed. I believe this and am counting on it. Go2.0 and beyond should be a solid choice. You should also note that it is entirely understood that more mature tech e.g. JVM have had the benefit of multibillion Dollar investment by SUN, IBM, Oracle, etc. I feel it is regrettable that (imo valid and reasonable) criticism of what is currently not up to par with this tech always seemingly requires a disclaimer that "I love Go". I have been using this language since the day it was released. I know it fairly well. I like it. But excessive hype and sensitivity around it is frankly somewhat irritating. peace out and happy v. day Go <3
  - enneff 12y ago
    Valentines day was yesterday for me. You wouldn't see me spending my time responding here if it were today!
eternalban 12y ago
Not an uncommon view: https://twitter.com/kellabyte/status/564531804837654528 https://twitter.com/kellabyte/status/564531804837654528 (That's not me, to be clear.) We all like Go. Just wish we could discuss these matters without unduly raising temperatures. "It's just code".
- twotwotwo 12y ago
  Sommers is an absolute beast, does totally astounding work and is an asset to the community. But even when we say "performance-critical" most of us don't mean getting 3M req/sec from one box like she did w/Haywire (https://twitter.com/kellabyte/status/547063455048404992 https://twitter.com/kellabyte/status/547063455048404992). In other words, pushing the hardware absolutely to its limits is another game (Sommers' game :) ) from simply getting a tricky part of your app performing at the level you need. And, confusingly, "high-performance" or "performance-critical" are terms you might use to describe either task. For context, the person whose presentation triggered Kelly's comment, MIT scholar Neha Narula, was experimenting with an 80 core machine, and she replied "it's kind of amazing I could push Go that far," and "to be fair they weren't really optimizing for my use case :)" -- her whole presentation is on YouTube at https://www.youtube.com/watch?v=Mbg1COjhsJU https://www.youtube.com/watch?v=Mbg1COjhsJU (some wild stuff--she got improvements for >48-core machines pushed into the Go GC) and those replies I quoted are at https://twitter.com/neha/status/564569903219634176 https://twitter.com/neha/status/564569903219634176 .
  - danieldk 12y ago
    But even when we say "performance-critical" most of us don't mean getting 3M req/sec from one box like she did w/Haywire We are not all writing web apps. Some of use are in machine learning, NLP, signal processing, etc. where squeezing out as much performance as possible does matter. In those fields Go is still weak. No autovectorization, no OpenMP, no direct CUDA integration, GC overhead, etc. Luckily, this can often be worked around since cgo is so good. One can write performance-intensive parts in C or C++, compile with the latest gcc or clang and link it with the Go code to drive it. This is often an understated advantage of Go compared to Java, where JNI calls are expensive. But the Go camp always advocate for porting everything to Go (because fast compile times).
twotwotwo 12y ago
I mean, Go is (or was) in the loop whenever YouTube hit its MySQL clusters (vitess) and on on the server providing downloads of Chrome and so forth (dl.google.com). CloudFlare has it sitting in the middle of every request for some sites (in the form of Railgun, their delta compression for pages). I'm not exactly a perf ninja and got some Go code packing Wikipedia history dumps at >100 MB/s. Dropbox uses Go for, their words, "our performance-critical backends" (https://blogs.dropbox.com/tech/2014/07/open-sourcing-our-go-libraries/ https://blogs.dropbox.com/tech/2014/07/open-sourcing-our-go-...). So folks manage to heavy lifting with it. I see "I couldn't possibly use X for performance reasons" here a lot, as an almost immediate response about a wide range of different tools, and two things come up in my mind: 1) you can always set the standard arbitrarily high. If you're doing AAA shoot-'em-up games or something, yes, use something else. 2) you're often not as good at tools that're new or different. It's possible you could go further with just a few more tricks about profiling or using free pools or whatever, or a little more info about how your code executes or what the runtime does. FWIW, if you hit a specific wall that's a problem for your app, folks on golang-nuts (or StackOverflow, where I've hung out sometimes) are often happy to try and help. Hope this is more helpful than fussy. Mostly just don't want folks to be discouraged into thinking certain things are impossible when in some cases they're really being done in production out there.
- coldtea 12y ago
  >I mean, Go is (or was) in the loop whenever YouTube hit its MySQL clusters (vitess) and on on the server providing downloads of Chrome and so forth (dl.google.com). Not as impressive as it sounds. Most of it is cached in memory anyway...
- tylertreat 12y ago
  Agreed with setting the standard arbitrarily high. It depends on what problem you're trying to solve—just like deciding when to use any other tool. Context matters. Where I work, we've been trying to build some super-fast systems and things like the GC and even calling interface methods matter. We open sourced some data structures that show just how optimized we're trying to get (https://github.com/Workiva/go-datastructures https://github.com/Workiva/go-datastructures), but in hindsight, Go might not have been the right tool for the problem.

eropple 12y ago

I don't believe that this is true. You use the exact same patterns and tricks in both for perf-critical code: off-GC primitives and object pools rule the day. What are you considering a "much better" option available in Go? (I considered stack-allocated structs in Go, but honestly that doesn't strike me as a particularly major thing; it may be slightly more terse, but fundamentally the same behavior.)

enneff 12y ago
Values ("off-GC primitives?") are first class-citizens in Go. Stack-allocated structs have much more value than you think.
- eropple 12y ago
  More value than I think? I'm pretty sure that I know exactly their value. I'll maintain that stack-allocated structs are a nice-to-have on top of the sort of stack-allocated primitives that Java provides; I'd like to have those structs as a convenience when I write Java, which is why I alluded to terseness in my prior post. But there's very little (or should be, I suppose, depending on implementation) performance difference to speak of between a struct and parallel declaration of the same values.
  - enneff 12y ago
    You said: > I considered stack-allocated structs in Go, but honestly that doesn't strike me as a particularly major thing; But for me they're one of the major ways in which I control memory use in Go programs. So, yeah, I think you underestimate them. No condescension implied. Apologies if it came across that way. I think we probably agree more than we disagree.
    - eropple 12y ago
      Yeah, I edited it out because after I took a breath I figured you didn't mean it that way. =) Hugs all around. But I really don't think it's a major thing, because there's no meaningful difference, in terms of performance, between "struct { int x; int y; } A" and "int Ax; int Ay;". I'm suspicious of claims that Go, as fundamentally a not that different language to a JVM language, is going to yield significant performance benefits. I'm not saying they aren't a nice convenience (value types are one of the things I love about C# when I'm writing code under MonoGame), I'm saying that I can't think of a reasonable way, barring bugs or short-sighted implementations, that they made for faster code.