September 20th, 2024

Optimizing Guile Scheme

David Thompson discusses optimizing Guile Scheme, highlighting strategies like minimizing memory allocation, using monomorphic functions, and employing profiling tools to enhance performance in game development and demanding applications.

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Optimizing Guile Scheme

David Thompson discusses optimizing Guile Scheme, a niche programming language he appreciates. Guile, a Scheme dialect, includes an optimizing bytecode compiler and a JIT compiler, which can enhance performance, especially in game development. Thompson shares insights from his experience with Chickadee, a game programming library, emphasizing that while Scheme is dynamic and limits compile-time optimizations, developers can still improve performance by following specific rules. Key strategies include minimizing memory allocation and preferring monomorphic functions over polymorphic ones to reduce runtime overhead. He explains that avoiding unnecessary allocations can significantly enhance throughput, particularly in performance-critical sections of code, such as graphics rendering. Thompson also highlights the importance of using tools like profiling and bytecode disassembly to identify and address performance bottlenecks. He provides examples, such as optimizing a variadic function to handle a limited number of arguments efficiently, which can drastically reduce garbage collection time and improve execution speed. By applying these techniques, developers can achieve better performance in their Guile applications, making it a more viable option for real-time graphics and other demanding tasks.

- Guile Scheme features an optimizing bytecode compiler and JIT compiler for performance enhancement.

- Minimizing memory allocation and using monomorphic functions can significantly improve execution speed.

- Profiling and bytecode disassembly are essential tools for identifying performance issues.

- Optimizing variadic functions can reduce garbage collection time and improve efficiency.

- Thompson's insights are particularly relevant for game development and performance-sensitive applications.

AI: What people are saying
The comments reflect a diverse range of opinions on optimizing Guile Scheme and the challenges of dynamically typed languages.
  • There are mixed feelings about dynamically typed languages, with some users appreciating their simplicity while others express frustration over performance issues.
  • Several commenters highlight the importance of inlining and optimization techniques, with requests for more detailed explanations of the optimizer's algorithms.
  • Some users advocate for the use of more performant alternatives to Guile, such as Common Lisp or Chicken Scheme, citing known performance issues.
  • There is a general appreciation for the resources and blogs available on optimizing Guile Scheme, particularly those by Andy Wingo.
  • Concerns are raised about the need for high-level languages to abstract away performance details, suggesting that users should choose tools that meet their performance needs.
Link Icon 12 comments
By @munificent - 8 months
I have such mixed feelings about dynamically typed languages. I've designed a whole pile of hobby programming languages, and dynamically typed languages are at least an order of magnitude simpler to design and for users to learn and start using.

At the same time, they inevitably seem to lead to user stories like this where a user really does know exactly what types they're working with and wants the language to know that too (for performance or correctness), and they end up jumping through all sorts of insane hoops to get the optimizer to do exactly what they want.

By @throwaway17_17 - 8 months
Solid blog overall and I think it is pitched at the right level of granularity for the topic. However, if I were offering criticism, the place I think more detail would be super interesting is the 'Please Inline' section. In particular, I would really be interested in a slightly more detailed description of the optimizer's algorithm for inlining. I think the "define_inlinable" macro is a great example of macro usage, but it is clearly a way to circumvent the inliner's apparent short comings. I would like to be able to understand what heuristic the optimizer is using to see if there is a sensible default function construction style/idiom that is more appealing to the optimizer for inlining. However, I am reminded of the inlining discussion in Chandler Carruth's talk (Understanding Compiler Optimization) from a few years ago where he discusses how obscure and seemingly arbitrary, in general, inlining heuristics and their optimization passes are in practice. [1]

1 - https://youtu.be/FnGCDLhaxKU?si=J3MhvJ-BmX5SG2N6&t=1550

By @samatman - 8 months
If you want to read just an enormous amount of well-written bloggage about optimizing Guile Scheme, this is the spot: https://wingolog.org

Andy Wingo is the maintainer and I get a kick out of everything he posts.

By @atemerev - 8 months
These sorts of optimizations can and should be handled by a (sufficiently smart (tm)) compiler.

Common Lisp/SBCL is usually sufficiently smart. I know not everyone likes Common Lisp, but at least I would have tested it with something more performant that Guile, like Chicken Scheme (my favorite!), Chez Scheme, etc.

I like Guile and its purpose as a universal scripting language. However, its performance issues are well known. Even compared to other scripting-first languages (Lua, Perl, Python etc).

By @pjmlp - 8 months
Great overview on how to approach improving code performance, without going down the usual route of rewriting into something else.
By @bjoli - 8 months
The guile source->source Optimizer is such a nice tool to see what is going on. Especially when writing macros. I really recommend Kent Dybvig's "the macro writer's bill of rights" to see how useful it can be.
By @anthk - 8 months
I prefer Common Lisp with SBCL and Lem, but this is good too.

On SICP, Guile badly needs a module for the picture language from the book (and srfi-203 + srfi-216).

By @ristos - 8 months
The monomorphic vs polymorphic argument is an interesting one. I think that you could explicitly get unboxing if you used something like CLOS style multimethods to dispatch based on the type, so that (add <float> <float>) would dispatch to the function that uses fadd on those operands. I never realized that you could use this kind functionality, multimethods or free monad interpreters, to write in-code optimizations that are conveniently abstracted away in actual code usage.

Edit: nevermind, that's also dynamic dispatch. You'd have to add static dispatch via macros or some external transpilation step.

By @pmkary - 8 months
Makes me happy when I see Guile is alive and going.
By @tightbookkeeper - 8 months
The full numeric tower sounds like a great idea. But in retrospect you almost never want uint32 silently converting to bignum, or ending up with a low precision float.

Has anyone had a positive experience?

By @orliesaurus - 8 months
As soon as I saw the title, I thought of the streetfighter character, but this was actually an interesting read on a programming language, I had never heard of before
By @exitb - 8 months
You probably shouldn’t do those things. The point of a high level language is to not have to think about such details. If you can’t get the performance you need, you should use a different tool, instead of trying to circumvent implicit limitations.