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Software is slow because of bad design, not slow languages (www.seangoedecke.com)
submitted 2 weeks ago by to c/programming@programming.dev
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[–] 27 points 2 weeks ago (20 children)

yeah, sometimes it feels like the same people complaining about python speed are the ones writing "C" code in python.

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  • [–] 9 points 2 weeks ago (19 children)

    What about the fact that runtime startup alone auto-disqualifies python for all short-lived process use-cases?

    Or the fact that you can't do concurrency especially across the language barrier from another language without multiple python runtimes orchestrated with a queue and IPC because of possible process-wide global state and similar concerns/assumptions for any python library dependency that is not all native across its own dependency chain?

    "languages are just tools" and "use the right tool for the job" were already stupid catch phrases. Pretending languages don't matter is a big further step into this shallow faux-intellectualism masquerading as wisdom.

    And we didn't even get to low level stuff yet.

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  • [–] 20 points 2 weeks ago (12 children)

    What about the fact that runtime startup alone auto-disqualifies python for all short-lived process use-cases?

    While Python's start-up time is a lot slower than a corresponding compiled program, in most cases it's not slow enough to matter even if the process itself is short-lived:

    $ hyperfine 'python3 -c "pass"'
Benchmark 1: python3 -c "pass" (412 runs)
                mean     ±       σ          min     …     max
  Wall Time      7.1 ms  ±     0.2 ms       6.7 ms  …     8.4 ms
  Memory         9.4 MiB ±     0.1 MiB      9.1 MiB …     9.5 MiB

    If you are running a small program so often that this kind of start-up time matters, then the loop should probably already be implemented in the program itself. In line with the article's thesis

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  • [–] -4 points 2 weeks ago* (10 children)

    Yeah nah, Lua runs circles around Python both at runtime and especially at startup. I've made me some desktop automation scripts in Lua to call from Alfred, I had to recheck that I didn't leave static test data in there instead of calling the script, because the results were appearing instantly.

    Recently had to develop a Python project, the tests took at least ten seconds to start each single time. This is while I made over a hundred tests for my module and re-ran them after every change.

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  • [–] 8 points 2 weeks ago* (last edited 2 weeks ago) (5 children)

    Recently had to develop a Python project, the tests took at least ten seconds to start each single time. This is while I made over a hundred tests for my module and re-ran them after every change.

    Python is dog slow, but if each of your tests are taking 10 seconds to start (not even run!), then something is catastrophically wrong with your setup. For comparison, for one of my projects, it takes a total of 12 seconds to run nox on a clean slate, which involves setting up venvs for five major versions of Python, installing the package and its dependencies in each, and finally running the 1500 test test-suite five times

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  • [–] 1 point 2 weeks ago* (last edited 2 weeks ago) (4 children)

    It wasn't my project. Afaict it's a standard pytest setup with the Litestar framework (unused in my tests) and an in-memory mock Postgre transaction with like five records per test, so choose for yourself which part of this is 'catastrophically wrong'. However, I can indeed agree that most of it is trash.

    Same approach with dozens upon dozens of tests worked snappily as heck in PHP, haven't yet tried it with my beloved Lua.

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  • [–] 2 points 2 weeks ago (3 children)

    Then its the Test environment that is slow, not Python.

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  • [–] 1 point 2 weeks ago* (last edited 2 weeks ago) (2 children)

    It is, yes. But I also commented on Lua vs Python, and if you even try to time them, Lua scripts will be finished before Python starts up. Lua is so fast that people mostly don't bother making libs for it in C, the fucking interpreter is quick enough for folks to skip any kind of compiling and just write libraries in the interpreted language. Oh, didn't I mention? The startup thing is with the interpreter, without any kind of bytescript, JIT and such.

    In the same vein, the K and Q languages and the KDB+ database by Arthur Whitney are so goddamn fast at array processing that they're used in banking for decades despite their extremely inscrutable syntax that would shear any Python programmer's head clean off. They just stay in the cache at most times. And they are also interpreted, not compiled at any time.

    Python suffers from the same shit as Java, it has to initialize hundreds of objects before the main program even starts, and then it creates hundreds more. Neither Lua nor JavaScript do that. PHP does to some extent, but the fucker is so fast that it can recreate the entire runtime context on every single request and then drop all of it afterwards, and it's still quicker than Python.

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  • [–] 3 points 2 weeks ago (1 child)

    The use case for Lua is very different from Python. It's not directly comparable, as Lua is barebones.

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  • [–] 1 point 2 weeks ago

    Lua is directly comparable to Python, as it's incredible at quasi-interactive scripting. Python actually fits better when startup time doesn't matter, while a Lua script can start and finish a dozen times before a Python process just turns on.

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  • [–] 2 points 2 weeks ago (3 children)

    Lua also doesn't provide everything Python does and has a totally different use case.

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  • [–] 1 point 2 weeks ago* (last edited 2 weeks ago) (2 children)

    Oh really? Well guess what, that's a huge benefit for Lua because its entire total size is around 500 KB. It's loaded into memory and executed start to finish faster than you blink. If you need a ‘standard library’, just use Penlight. As I already mentioned, vast majority of libraries for Lua are written in... Lua itself, because it's so goddamn fast. I'm using Fennel, the Lua Lisp that's transcribed on-the-fly, and it's still faster than Python. Lua is great for interactive tasks like desktop automation, e.g. with Alfred, Hammerspoon (which latter uses Lua throughout), or for scripting in Termux on the phone where Python would kill the memory immediately.

    Lua's problems with the absence of popular libraries aren't because of any language issues (even the lack of null can be dealt with), but solely due to its non-adoption in the masses. It is very popular as an embedded language in gaming, though, and that's not a coincidence, because it fits that niche precisely because of its small size and extraordinary speed.

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  • [–] 2 points 2 weeks ago (1 child)

    Well guess what, that’s a huge benefit for Lua because its entire total size is around 500 KB.

    Filesize doesn't matter, if the functionality is missing. Lua is just not a direct comparison and replacement for Python. Penlight isn't standard library. In example if I want to write a commandline script, I better off doing it in Python. The language is much better to me, has better features, has a standard library builtin and is even installed in all Linux distributions.

    Lua is meant to be embedded into other applications, not meant to be used on its own.

    Lua’s problems with the absence of popular libraries aren’t because of any language issues (even the lack of null can be dealt with), but solely due to its non-adoption in the masses.

    Wrong. This is a design choice, because Lua isn't meant to be used by its own. The embedded environment is meant to provide the functionality. In example in Neovim they provide their own functionality embedded within the editor. I can't use that script on a different environment.

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  • [–] 1 point 2 weeks ago* (last edited 2 weeks ago)

    Filesize doesn’t matter, if the functionality is missing.

    Lua is meant to be embedded into other applications, not meant to be used on its own.

    Wrong. Lua is meant to be used on its own, because it's so freaking good. It provides everything one needs to begin, while allowing for a wide array of libraries to be made. But I know you haven't made any serious number of scripts in either language, simply because you claim 'filesize doesn't matter', while Lua is so fast partly because of its size.

    This is a design choice, because Lua isn’t meant to be used by its own.

    Wrong again. Lua is amazing on its own, but third-party libraries make it even better.

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  • [–] 5 points 2 weeks ago (4 children)

    Or the fact that you can’t do concurrency especially across the language barrier from another language without multiple python runtimes orchestrated with a queue and IPC because of possible process-wide global state and similar concerns/assumptions for any python library dependency that is not all native across its own dependency chain?

    This is very out of date. I haven't written Python for over 4 years and even back then, I was using multiprocessing.Pool for pretty much all parallel processing that I ever needed. Sure, it's doesn't fit every use case for concurrency, but for simple stuff it's perfectly fine.

    Not only that, it's one of the simplest parallel processing APIs I've ever used:

    from multiprocessing import Pool

def f(x):
    return x*x

if __name__ == '__main__':
    with Pool(5) as p:
        print(p.map(f, [1, 2, 3]))
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  • [–] 1 point 2 weeks ago (3 children)

    It's not outdated, and maybe you didn't get what I was talking about, but probably because I didn't word it well. So let me quote someone else instead:

    While pure Python code should work unchanged, code written in other languages or using the CPython C API may not. The GIL was implicitly protecting a lot of thread-unsafe C, C++, Cython, Fortran, etc. code - and now it no longer does. Which may lead to all sorts of fun outcomes (crashes, intermittent incorrect behavior, etc.)

    This covers the layers below python, but still doesn't fully cover the process wide restrictions (it's not just about thread safety, global initialization and resources are very relevant too). It also doesn't cover the exact same problem which also exists for any layer calling into python from above, which also relies/relied on the GIL for synchronization. This means that you can't effectively, confidently, and safely scale python without scaling the number of python runtime instances, each in its own full OS process.

    The fact that multiprocessing became popular, instead of just scaling/parallelizing with threads, is itself an extension of the GIL/no-GIL circus. But its not the primary point here.

    So not only the proposition (which someone referenced in another sub-thread) to move everything into python is in and of itself a self-defeating argument, since it proves a language being a problem (through forcing language lock-in). But even within a language (python), not all problems are solvable still.

    Note that this is not all theoretical for me. In one of my previous projects, I had to call into a python library (which didn't have an adequate alternative) from rust code (through pyo3). And I was forced to scale with multiple python runtimes, each getting one request/message at a time.

    And we still didn't get to any low-level details yet 😉

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  • [–] 2 points 2 weeks ago (2 children)

    Ah okay, I see what you're saying. GIL removal can break FFI code through the C API.

    I have a lot of thoughts on this, and most of it is too incoherent to put into a comment someone else can understand, but for the most part, I think the issues are still pretty overblown. I just can't see a world where Python needs true multithreading support when multiprocessing works just fine for most applications. You find a hot loop, you parallelize it in multiprocessing and just like that, your process runs much faster.

    I do think that GIL removal is a terrible idea in general, for the reasons in the quote you provided, but at least it's optional. I would personally not enable it in anything I maintain for several years if I didn't have to.

    I also think that polyglot code running in the same process is also a bad idea. I can understand calling C or Fortran from Python for numerical processing for example, but doing the reverse (like calling Python from Rust) is something I try to avoid at all costs. In any project I've worked on, if significant portions of the codebase were written in different languages, you would just use something like protobuf to specify the I/O protocol between the different languages and call them across a socket. It's easier to maintain in my opinion since it defines a concrete boundary between the two different portions of code, and also makes it much easier to test each component separately too.

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  • [–] -1 points 2 weeks ago (1 child)

    If you didn't automatically register that requiring spawning full OS processes to scale performance immediately disqualifies a language from a whole plethora of use-cases (which is what the intellectually deficient OP tried to argue against), then I'm not sure you're qualified to opine on the matter (hint: spawning a thread per task is already too much overhead for many workloads). And I don't mean any disrespect to you here. Your replies were far from the worst in this thread.

    Frankly this thread has been very illuminating. My perception of the average p.d user and their concrete knowledge was very inflated.

    And we didn't even get to low level stuff yet. People are already failing at the macro level. Sad.

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  • [–] 4 points 2 weeks ago

    If you didn’t automatically register that requiring spawning full OS processes to scale performance immediately disqualifies a language from a whole plethora of use-cases

    That's way too broad of a statement to be true in any absolute sense. It really depends on what you're doing, and sure, there are plenty of ways to do it stupidly, but a lot of people that are smarter than you and me have thought about ways that the overhead of spawning processes can be mitigated. All I can say is that I've had perfectly good success using multiprocessing.Pool and getting near perfect speedups. Is it as fast as threading? No. But it's good enough. If it's not good enough for you, then maybe we just have different use-cases, but without talking about concrete examples, we can't make any specific claims.

    And we didn’t even get to low level stuff yet. People are already failing at the macro level. Sad.

    What do you want to talk about? Are you writing kernel drivers in Python or something? Why would we talk about writing low level code in Python, that sounds absurdly stupid. Most of the high performance libraries people use are written in Fortran or C. The entire field of data science uses Python, if performance were not a heavily optimized problem, then a lot of people out there must really love wasting their money on compute. Python is a glue language for high performance low level code, everybody knows this already.

    Frankly this thread has been very illuminating. My perception of the average p.d user and their concrete knowledge was very inflated.

    At least we agree on something!

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