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Why is BIND 10 written in C++ and Python?

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Re: Why is BIND 10 written in C++ and Python?

#91

Post by haberman »

CJefferson wrote: post #38
btipling wrote: post #27

> "C lacks good memory management" C lets you manage memory without possibly inefficient or even broken magical black box automated processes or garbage collectors. Maybe what the author meant to say was "C lacks easy memory management."

Consider realloc. Seems like a sensible function, with its ability to extend memory blocks in-place. Except, you can't try to extend a memory block in-place, but not move it if it can't be extended. malloc and friends really are a quite poor way of managing a memory space if you want to do even slightly clever things I find, unfortunatly

The magic of C is that no one is making you use realloc() if you don't want to. realloc() is also written in C. You can write your own, and people do, all the time.

Re: Why is BIND 10 written in C++ and Python?

#92

Post by alexchamberlain »

antirez wrote: post #81

Quoting from the article, with my replies: > String manipulation in C is a tedious chore. Use a dynamic strings library, like Postfix for instance, and everything else. > C lacks good memory management. So strange that you went for C++ for most of your code that is not immune of problems from this point of view. I could understand that point if you were opting for a language with GC support. With C you can easily get…

Too performance critical for a GC! Reference counted all the way.

Re: Why is BIND 10 written in C++ and Python?

#93

Post by webreac »

justin66 wrote: post #47
nicholassmith wrote: post #13

I think it's interesting that they did consider C and then decided it was too much of a risk. There's a constant theme of 'why use C++? C is faster and doesn't suck as much!' especially due to Linus' statements on the language, but often C is a technical risk as there's so much more that can go wrong. I'm not saying C++ is a better language than C, but it's definitely different and given the language is structured to…

It's a tangent, but: has Linus ever given a presentation that involved actually discussing code? Perhaps code projected on a screen, even part of a slideshow? It's odd that he's such an accomplished engineer but every presentation I've seen him give involves saying outrageous things while starry-eyed geeks stare at him adoringly. If it weren't for the fact that he's arguing from a position of (very great) authority,…

Presentations is not his job. I remember in 1992 when he has tried to compile the kernel using g++ mode. Compiling C in C++ mode was a way to detect more errors and to support migration toward C++. A lot of nasty bugs in g++ were discovered thanks to Linus. His main concern was that code generated by g++ was a lot slower than C. Many optimisations were not possible due to the language.

Re: Why is BIND 10 written in C++ and Python?

#94

Post by thwest »

antirez wrote: post #88
alpatters wrote: post #87

Earlier quoted context omitted.

> With C you can easily get better (that is, safer) than C++ native MM just building a reference counting system on top of your C "objects". Why build your own when C++ has std::shared_ptr.

I was referring about how to do it with C.

How is a C implementation of std::shared_ptr safer?

Re: Why is BIND 10 written in C++ and Python?

#95

Post by rz2k »

bnegreve wrote: post #16
EwanToo wrote: post #7

There's a comment in the post: "As of right now, it ends up that about 75% of our code is C++ and 17% is Python (link) since it turns out that a lot of BIND 10 is performance-critical." Which could easily be taken the wrong way. I believe the right way to think about it is "How much _more_ C++ code would there be, if there wasn't that 17% in Python?".

Hum, I don't think interpreting this comment as Python is not adequate for performance critical applications is misinterpretation. The author makes it very clear in some other part of the text: > [Python] has all of the features that we were looking for… except performance. Now your interpretation is also valid since they could have written everything in C++ but they didn't.

I think the issue is that the percentages may be measured in lines of code.

If one language is more verbose, counting lines of code will throw off conclusions about how much functionality is implemented using each language.

Re: Why is BIND 10 written in C++ and Python?

#96

Post by qdog »

raverbashing wrote: post #31
btipling wrote: post #27

> "C lacks good memory management" C lets you manage memory without possibly inefficient or even broken magical black box automated processes or garbage collectors. Maybe what the author meant to say was "C lacks easy memory management."

Funny you mention "black box automated process" because, what do you think malloc is? There are two ways of allocating memory directly from the kernel (IIRC), brk and mmap. There's some management malloc does, and if it's good or not depends on you application. For example, size, number and behaviour of your allocations. Depending on your situation you may want to do your own memory management.

When I worked on embedded systems, we didn't use malloc() at all, just some heap functions. Even after that, there have been times where I worked on projects where there was a single malloc() and that was turned into a memory heap.

However, a call to malloc() is pretty straightforward, you expect it to return a pointer to the allotted memory, or not. Using a GC or the boots libraries is not quite as straightforward, and the black box is a lot bigger.

Re: Why is BIND 10 written in C++ and Python?

#97

Post by rlpb »

eropple wrote: post #90
StefanKarpinski wrote: post #30

Go seems like it would have been perfect here, but of course, the language wasn't even a glimmer in Robert Griesemer, Rob Pike, and Ken Thompson's collective eye yet.

Obviously I can't speak for these guys, but if I were designing it the fact that Go uses a garbage collector is a pretty strong minus. I like GC'd languages for a lot of tasks, but if I care about performance to the extent that they need to with BIND, I'm not going near it.

Interestingly, they actually wanted a garbage collector:

"The language had to address most of the problems with C. Ideally this meant something with good string handling, garbage collection, exceptions, and that was object oriented."

Re: Why is BIND 10 written in C++ and Python?

#98

Post by muks »

antirez wrote: post #88
alpatters wrote: post #87

Earlier quoted context omitted.

> With C you can easily get better (that is, safer) than C++ native MM just building a reference counting system on top of your C "objects". Why build your own when C++ has std::shared_ptr.

I was referring about how to do it with C.

Hi antirez

C doesn't have a destructor that gets called when something goes out of scope. That's taken advantage of in C++ (RAII) to implement various things (like scoped_ptr that helps avoid leaks).

Refcounting is also not perfect for every case.

But I like and prefer C. ;) Just pointing out one thing different in C++.

Re: Why is BIND 10 written in C++ and Python?

#99

Post by beagle3 »

justin66 wrote: post #47
nicholassmith wrote: post #13

I think it's interesting that they did consider C and then decided it was too much of a risk. There's a constant theme of 'why use C++? C is faster and doesn't suck as much!' especially due to Linus' statements on the language, but often C is a technical risk as there's so much more that can go wrong. I'm not saying C++ is a better language than C, but it's definitely different and given the language is structured to…

It's a tangent, but: has Linus ever given a presentation that involved actually discussing code? Perhaps code projected on a screen, even part of a slideshow? It's odd that he's such an accomplished engineer but every presentation I've seen him give involves saying outrageous things while starry-eyed geeks stare at him adoringly. If it weren't for the fact that he's arguing from a position of (very great) authority,…

Ah, but he has earned this position of authority by actually delivering. He did not get that position of authority randomly, nor by an act of nepotism nor by making promises during an election.

First, by delivering working code that ended by running the majority of phones and smart devices out there. Also, by revolutionizing source code control. No, he didn't invent (almost) any of the concepts behind git, and by now the majority of the code was not written by Linus. However, he was able to strike a balance between features, usability, speed and working model that DID revolutionize version control. Monotone pioneered a lot, but was too slow and cumbersome; so was Bazaar without pioneering much. BitKeeper had a lot of things going for it, but freedom and price working against it. is more or less on par with git, but it's git that brought the revolution.

Second, by being able to successfully manage more than one huge project with hundreds of contributors, all of whom he can fire at, but which he didn't actually hire (nor can he, if he needs more work).

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