4 ms·

> I don't see any major con if it was written in Python > it would be a tad slower a tad? I'll use C++ as an example, but the last time I profiled a hash map

by _gabe_ 4y ago

> I don't see any major con if it was written in Python > it would be a tad slower a tad? I'll use C++ as an example, but the last time I profiled a hash map in C++ vs C#, the C++ lookup took 1 nanosecond[0] and the C# version took 1ms (1000x slower) (I don't have these metrics anymore but I believe it was one ms or slower, and Google seems to confirm that). Now, if the difference between C++, a machine compiled language, and C#, a runtime compiled language, is 1000x for a very common operation, how much slower will an interpreted language that is running at an even higher level be?? The reason 90% of our apps are such slow trash these days is because programmers think that there is no difference in a couple milliseconds when it is a huge difference if that couple milliseconds is being run thousands of times through hundreds of thousands of lines of code! Take a look at how fast the Jai compiler is compared to a modern C++ compiler. Or even a C compiler vs a C++ compiler. It's night and day because of how much cruft slowly gets added on. So I find your claim that most of the Unix utilities are only written in C because that was mainstream in the day highly dubious. If anything, they would be written in something like Rust today, but definitely not JS or Python. Edit: I would also like to point out how much of a pain it would be to write low level network code, like what's necessary in curl, in a language like Python. When you're writing low level net code you want as little interference between the bytes and the programming language. Because if your bytes have some hidden padding, or the endianess is swapped, or a data structure is aligned a byte off, it means the difference between between correct transfer over the net, and sending garbage over the net. Python is not conducive at all to understanding how an object will be transformed into q series of bytes, whereas C is almost a direct translation from a struct to a series of bytes. [0]: https://gist.github.com/ambrosiogabe/66a6e2fdc77e6a600e570f4639222120 https://gist.github.com/ambrosiogabe/66a6e2fdc77e6a600e570f4...

weatherlite 4y ago
I might be wrong about curl - I use it just as a tool to make http calls but it might be more complicated than that - but why can't you build curl with python's http libraries? I guess there are use cases where you have to manipulate responses on the byte level?
- deleted 4y ago
  [deleted]
nayuki 4y ago
> the C++ lookup took 1 nanosecond[0] and the C# version took 1ms (1000x slower) The ratio between 1 ns and 1 ms is a million.
- flohofwoe 4y ago
  The link talks about nano- vs micro-seconds, so probably just a typo.
  - _gabe_ 4y ago
    I just re-ran the benchmarks and I was mis-remembering those statistics quite a bit. It looks like C# takes 124.5 nanoseconds on average for a hash set lookup. This was benchmarked using BenchmarkDotNet :)
cpurdy 4y ago
C# definitely does not take 1ms to look up something in a hash map. Perhaps 1us (microsecond) in a horrible example if the virtual hash code has a slow algorithm and doesn't cache the result. Regardless, the benefit of not using C++ is and always has been: Not having to use C++.
- _gabe_ 4y ago
  Yep you are correct, I was mis-remembering quite a bit. I just re-ran the tests using BenchmarkDotNet and C# takes 124 nanoseconds on average, which is still 100x slower and a considerable difference, but not orders of magnitude difference :) C# benchmarks on my machine. FastFindRecipe just does a hash set lookup, it looks like this: private static readonly HashSet<CraftingRecipe> FastList = new HashSet<CraftingRecipe>(new CraftingComparer()); public static CraftingRecipe? FastFind(CraftingRecipe r) => FastList.TryGetValue(r, out var res) ? res : null; | Method | Mean | Error | StdDev | Min | Max | |--------------- |---------:|--------:|--------:|---------:|---------:| | FindRecipe | 315.2 ns | 1.17 ns | 1.09 ns | 313.6 ns | 317.4 ns | | FastFindRecipe | 124.5 ns | 0.23 ns | 0.21 ns | 124.1 ns | 124.9 ns |
  - avgcorrection 4y ago
    > , which is still 100x slower and a considerable difference, but not orders of magnitude difference :) Two orders of magnitude.
wing-_-nuts 4y ago
I see this sort of argument for low level, system languages all the time. What you're not considering is that runtime isn't the constraint that we're hitting anymore, it's developer time. There's no doubt that a good python dev is much more productive than a good c dev, both in terms of raw output, and in terms of writing code with fewer bugs. 'Software is eating the world' is overused, but broadly true, and the reason we devs are so well paid is because the demand so vastly outstrips the supply of productive devs.
- _gabe_ 4y ago
  My argument here is about developer time though. Python development for low level systems programs would be astronomically slower than using a language like C, C++ or Rust which are built for these things. Use the proper tool for the proper job. If you have to have multiple structures that need to be precisely laid out in binary, python is the wrong tool for the job. Delivering content using Tcp or Udp packets requires very explicit binary definitions of the data your sending. Sure you can use a wrapper on top of a library that deals with the low level stuff, and that's what Python is all about. Use the proper tools for the proper jobs. If you're using C to write one off scripts or simple data manipulation like analyzing csv contents or something, then you should probably use a higher level language instead. If though, like curl, you have to be very explicit about the binary description of objects to accurately send and receive those objects between a network, then use a low level language. > runtime isn't the constraint that we're hitting anymore If you're sending data over the network you're absolutely hitting this constraint. Reading some data from RAM is on the order of like nanoseconds, sending data over the network is on the order of hundreds of milliseconds depending on the size and location you're sending that data. When it comes to sending data over the network, literally every byte does matter.
  - wing-_-nuts 4y ago
    My point was more broad. We're not short on compute power in most cases, we're short on dev time. If you're talking low level microcontroller stuff, or bit banging, sure, do it in C if you like. In general though, I'd rather devs using a higher level language that gives them tools to deal with things like memory management and concurrency. The slowest code is the code that was never written, not the code that takes an extra 100ms because it was done in python instead of C.

by _gabe_ 4y ago

weatherlite 4y ago

I might be wrong about curl - I use it just as a tool to make http calls but it might be more complicated than that - but why can't you build curl with python's http libraries? I guess there are use cases where you have to manipulate responses on the byte level?

deleted 4y ago
[deleted]

nayuki 4y ago

> the C++ lookup took 1 nanosecond[0] and the C# version took 1ms (1000x slower) The ratio between 1 ns and 1 ms is a million.

flohofwoe 4y ago
The link talks about nano- vs micro-seconds, so probably just a typo.
- _gabe_ 4y ago
  I just re-ran the benchmarks and I was mis-remembering those statistics quite a bit. It looks like C# takes 124.5 nanoseconds on average for a hash set lookup. This was benchmarked using BenchmarkDotNet :)

cpurdy 4y ago

C# definitely does not take 1ms to look up something in a hash map. Perhaps 1us (microsecond) in a horrible example if the virtual hash code has a slow algorithm and doesn't cache the result. Regardless, the benefit of not using C++ is and always has been: Not having to use C++.

_gabe_ 4y ago
Yep you are correct, I was mis-remembering quite a bit. I just re-ran the tests using BenchmarkDotNet and C# takes 124 nanoseconds on average, which is still 100x slower and a considerable difference, but not orders of magnitude difference :) C# benchmarks on my machine. FastFindRecipe just does a hash set lookup, it looks like this: private static readonly HashSet<CraftingRecipe> FastList = new HashSet<CraftingRecipe>(new CraftingComparer()); public static CraftingRecipe? FastFind(CraftingRecipe r) => FastList.TryGetValue(r, out var res) ? res : null; | Method | Mean | Error | StdDev | Min | Max | |--------------- |---------:|--------:|--------:|---------:|---------:| | FindRecipe | 315.2 ns | 1.17 ns | 1.09 ns | 313.6 ns | 317.4 ns | | FastFindRecipe | 124.5 ns | 0.23 ns | 0.21 ns | 124.1 ns | 124.9 ns |
- avgcorrection 4y ago
  > , which is still 100x slower and a considerable difference, but not orders of magnitude difference :) Two orders of magnitude.

wing-_-nuts 4y ago

I see this sort of argument for low level, system languages all the time. What you're not considering is that runtime isn't the constraint that we're hitting anymore, it's developer time. There's no doubt that a good python dev is much more productive than a good c dev, both in terms of raw output, and in terms of writing code with fewer bugs. 'Software is eating the world' is overused, but broadly true, and the reason we devs are so well paid is because the demand so vastly outstrips the supply of productive devs.

_gabe_ 4y ago
My argument here is about developer time though. Python development for low level systems programs would be astronomically slower than using a language like C, C++ or Rust which are built for these things. Use the proper tool for the proper job. If you have to have multiple structures that need to be precisely laid out in binary, python is the wrong tool for the job. Delivering content using Tcp or Udp packets requires very explicit binary definitions of the data your sending. Sure you can use a wrapper on top of a library that deals with the low level stuff, and that's what Python is all about. Use the proper tools for the proper jobs. If you're using C to write one off scripts or simple data manipulation like analyzing csv contents or something, then you should probably use a higher level language instead. If though, like curl, you have to be very explicit about the binary description of objects to accurately send and receive those objects between a network, then use a low level language. > runtime isn't the constraint that we're hitting anymore If you're sending data over the network you're absolutely hitting this constraint. Reading some data from RAM is on the order of like nanoseconds, sending data over the network is on the order of hundreds of milliseconds depending on the size and location you're sending that data. When it comes to sending data over the network, literally every byte does matter.
- wing-_-nuts 4y ago
  My point was more broad. We're not short on compute power in most cases, we're short on dev time. If you're talking low level microcontroller stuff, or bit banging, sure, do it in C if you like. In general though, I'd rather devs using a higher level language that gives them tools to deal with things like memory management and concurrency. The slowest code is the code that was never written, not the code that takes an extra 100ms because it was done in python instead of C.