Why does everyone love being able to control the allocator in Zig? I rarely want this low level control over the allocator, I would rather have an easy to use interface to malloc/free (such as RAII) or would prefer the language push me to avoiding allocations when unnecessary. C and Zig users are always talking about how arena allocators are easier to use than the alternative but I disagree because the alternative is extremely easy to use when the language makes it so.
Arenas have a lot of footguns like growing out of control if you don't have space in your logic to delete them (e.g. suppose every new HTTP connection required obtaining a new allocation from the primary arena -- now you have a memory leak). They also aren't necessarily faster than malloc: I remember hearing a case where mimalloc was faster than an arena for a one-shot program like a linker because reclaiming space improved cache locality. Plus it's difficult to implement things like growable vectors or hashmaps using an arena without wasting space.
I just don't see how "futz about with the allocator constantly" and "use an arena" is actually a good default.
It is a good default for lib code because it makes that code truly re-usable. The same is true for great C libraries, they let you provide a block of memory instead of calling malloc inside. The library should not get to decide if/when allocations should be done.
In Zig app code you don't have to pass allocators all over if you don't want to, that's your code so do what you want. But for libraries it's the right thing to do because it puts the caller in control.
The reason you have to pass allocators instead of making this implicit like in e.g. Odin, is because Zig just takes a firm stance against implicit logic, firmer than any other language I've ever used. The end result is that people who like Zig tend to like passing allocators around even in their own code.
The library developer doesn't know what allocator will be passed, and the library user doesn't necessarily know how it will be used. They share an interface, so it will [probably] work, but it might not behave (mem/perf wise) as either expects. ArenaAllocators in particular don't play great with ArrayLists or nested ArenaAllocators.
I don't think it's a huge problem, but it's more subtle than an explicit allocator is a better because it provides more flexibility.
> Zig just takes a firm stance against implicit logic
I bought that as Zig's M.O., but then came the automatic "async/IO" colorless functions which is a huge chunk of implicit and hidden logic.
That's more implicit logic than what's in say JavaScript async AFAICT. Arbitrary int sizes with implicit casting rules, etc. More recently was the attempts of memory safety via an some sort of (optional) implicit GC mode. Personally I don't get it.
The async design changed multiple times, and the current approach is that of requiring passing an I/O interface that encapsulates the logic, same approach as for passing around an allocator.
This effectively makes all I/O bound code "quasi-async", and it's all explicit and the caller is in control.
That just means you haven't run into the problems yet that a global allocator brings with it. Other people have and welcome the better control over allocation provided by the Zig std library. The challenge is of course to balance convenience and flexibility. Also if you write code that prefers to not allocate in the first place (which should be the default), you're not affected anyway.
If you don't like arenas then that will push you towards avoiding allocations :)
I don't love malloc / free, managing frees one-to-one with allocations is a nightmare. An HTTP server is actually a great example of a good fit for arenas... you can have an arena created per connection, and then free the arena when the connection closes. Now all of your allocations during that connection are guaranteed to be freed instead of having to keep track of them individually. Need something to live across connections? Use the general purpose allocator for those particular things.
For one shot programs, why bother freeing anything at all? The gpa or malloc or whatever else is fine there.
Personally I mostly lean on fixed-size buffers, but if I'm writing Zig it's just little toy programs where blowing up when the buffer runs out of room is fine. But for big non-toy programs it might be good to use fixed-size buffers anyway and define your limits in terms of things actually relevant to your domain.
RAII and smart pointers are fine too, but C++ has you covered if you want those. Zig is specifically avoiding that kind of invisible code that destructors bring you.
> Now all of your allocations during that connection are guaranteed to be freed instead of having to keep track of them individually
And how do you size the arena?
> keep track of them individually
I think this is an exaggeration of the problem. This is what RAII semantics in C++ are for.
> avoiding that kind of invisible code
The invisible code is traded for defer statements right after initialization that are obvious and therefore mostly just noise, and also a problem if you forget to call them. This isn't an issue with RAII. I get the point of not wanting invisible code, but defers don't seem much of an improvement either. A trade-off at best.
Two options: you either say "eh 20MB per request ought to be big enough" and resize it later if you need to. Or you take time to figure out reasonable limits in terms of whatever domain you're dealing with, and return descriptive errors when those limits are exceeded. Maybe you're saying your service supports up to N HTTP headers and M query parameters in the URL and so on. For almost anything there's a limit you can place that's reasonable. Having no limits at all just means the limit is when you run out of memory / disk / whatever.
If you like RAII and C++ just use that though, Zig is an alternative not an upgrade, imo.
> If you don't like arenas then that will push you towards avoiding allocations
I mean push in the sense of a pit-of-success, not making me do things because the alternative is unpalatable.
> managing frees one-to-one with allocations is a nightmare
It really isn't a nightmare if your language has tools to help you. I'm never particularly concerned about frees in Rust outside of thinking about room to optimize.
> Need something to live across connections? Use the general purpose allocator for those particular things.
Well, this is a determination you have to make very carefully and if you screw it up (like in the situation I was trying to outline) you have a subtle bug.
> Personally I mostly lean on fixed-size buffers, but if I'm writing Zig it's just little toy programs where blowing up when the buffer runs out of room is fine.
What's also fine is using malloc, which will have perfectly reasonable performance for your toy programs.
This is reinforcing my belief that Zig programmers actually just have a sort of aesthetic attachment to the idea of managing their allocations themselves and this has very little to do with the actual practical concerns of writing software that works. I'm a lot more sympathetic to the other reply that talked about library code improving flexibility for those relying on the library, than this comment that only thinks about the case where everything goes perfectly and using a fixed size buffer for no reason.
> I'm never particularly concerned about frees in Rust outside of thinking about room to optimize.
Zig's position, love it or hate it, is that you should be thinking about it. Dropping a Vec<String> in Rust is O(n). Have you ever clicked the X on an app and it takes 10 seconds to disappear? Stuff like this is part of the problem. You shouldn't have to traverse your process's whole memory space just to call exit(0).
If you have to write that for loop, the O(n) will jump out at you and push you towards an arena or FixedBufferAllocator or std.process.cleanExit, or any other solution to avoid the loop.
Just to let you know, `std::process::exit(...)` in Rust does not call any destructors. C++ also has `std::quick_exit(...)`. Applications exiting slowly is a problem caused by app developers.
(There are cases where it also takes time because the OS does have to flush all open files during process teardown, etc., but this shouldn't generally be user-visible.)
Dropping vecs that contain strings does not make any Rust code in the real world slow. You would need to have a vec containing billions of strings, occupying several gigs of memory, before dropping such a structure took any perceptible amount of time. And for extreme cases like that, you can simply use arenas. The bumpalo crate is approximately as old as Zig is. The reason that people so rarely turn to arenas in Rust isn't because you can't do them, because you've always been able to, but rather because arenas are a very specific solution to a specific sort of memory access pattern, and going out of your way to strictly adhere to that pattern doesn't produce measurable differences for most software.
> This is reinforcing my belief that Zig programmers actually just have a sort of aesthetic attachment to the idea of managing their allocations themselves and this has very little to do with the actual practical concerns of writing software that works.
Indeed if you don't want to manage everything yourself I don't think there's a need to use Zig. The whole pitch is making everything explicit and not hiding control flow. And I do think that limits its usefulness to smaller-scale codebases.
Writing quality software doesn't require much from the programming language until your codebase gets very large and you're collaborating with a ton of people. If I'm expecting a codebase to grow to a large scale I'm not reaching for Zig for that. I don't trust _myself_ to keep that much Zig code tidy and correct let alone a big mob of developers and agents :)
Passing allocator pointers around has the advantage of allowing you to customize the allocator when you want, and to ignore it when you want (which is most of the time), i.e. just use the allocator you were given and pass it around like some piece of syntax or ctx in Go.
The trouble comes when you have data structures that manage memory, and you want to associate the allocation strategy with the particular instance of the data structure. Or, worse, you don't store the allocator pointer with the data and you require that all functions operating on the data structure happen to use compatible allocators.
At its simplest, though, passing allocators around is just removing an implicit global variable that is sometimes helpful to customize locally, but nearly impossible to customize locally if left as a global.
Allocators help solve the problem of "this code I want to use is almost good enough; how do I actually use it?"
I distinctly remember one of my first "real" jobs, somebody had written a C# library for GraphQL. It had some sort of bug or lack of functionality I had to fix. The author had fallen hook, line, and sinker for sealed classes and all that nonsense, so the shortest path to using the rest of their code was to fork the library and re-write the thousand offending lines and all references thereto. Luckily it wasn't a deep dependency.
Contrast that with similar issues in typical Python. The library likely accepts my favourite duck-typed solution, if it doesn't then I can likely work around it with an appropriate choice of dunder methods in the code I have interacting with the library, and if it still doesn't yield then I can just rewrite (monkey-patch) the offending code at runtime.
Not that either of those scenarios are objectively optimal, but they illustrate one of the principles people have in mind when they use an interface like allocators (not the only one, I'm sure other commentors will talk your ear off), that when push comes to shove you'd prefer to be able to use your existing code to solve your new problems. And that does empirically mostly work here; you can use nearly the entire Zig stdlib (especially when ignoring things like the posix namespace) and most of the rest of the ecosystem as well on embedded devices, in WASM, in bounded-memory applications, in generic application code, in fast-running CLI apps not even bothering to free, etc.
I agree with much of your discussion about arenas by the way. They're a moderately poor fit for the current interface in Zig, largely because the free functionality is questionable at best. IME, most uses of arenas actually know they need such a thing. Functions taking allocator arguments and expecting the allocator to be an arena should take an arena argument. When using arenas for lifetime management, something should probably own that arena rather than implicitly assuming whatever gets passed through the stack is correct. Passing arenas to arbitrary functions expecting general-purpose allocators is prone to leaks, and you'd be better off using the arena (or a buffer created therefrom) as a backing allocator for a data structure capable of actually freeing if you can't trust the implementation you're calling into (and if you can trust it, they should expose a better API allowing you to detect that trustability at the callsite).
If you had to pick a default, an arena allocator would definitely be it. Although even better would be a fixed-size arena that can never grow, like Tigerbeetle does.
I don't think the footguns you're talking about are real by the way.
arena's are popular in part because they are a way of grouping allocations by a single lifetime, reducing the amount of use-after-free's or double-free's that occur (reducing, not eliminating them).
they make a lot less sense in languages where the compiler or runtime takes care of this for you.
mimalloc aggressively reclaims space and it benefits the use case in our Dip database built on rust.
This is for a long running process where consuming compute and memory should only occur on processing a request and must revert to a baseline memory consumption once the request is completed.
malloc with default allocator always gradually increases the memory consumption. This continues with enough request bursts on our testing until the process runs out of memory. mimalloc doesn't.
On mobile, we are stuck with the default allocator. On mobiles, the phenomenon of the default allocator consuming memory is reproducible even with normal Qt apps. It is what it is.
That's just a matter of wrapping the allocator if you feel fhat is better approach. Question is, should there always be an allocator around with arr or do you want to split a build phase from an immutable use phase.
That's because in Zig that would be seen as a surprise side effect - the allocator is expected when the action is performed, not when it's "prepared", this way you know append() allocates. Otherwise it wouldn't be explicit which Array methods allocated.
The Odin way is useful, too. Depends on what you're building.
The article says some Zig advantages but it's worth noting that all these advantages are tradeoffs.
Zig makes handling error easy but makes retaining error information hard. The result is that Zig developers either write more code than other languages to store diagnostic information, or just simply discard diagnostic information. The second makes it much harder to debug because the useful error information is discarded.
About the TigerStyle, it's worth noting that TigerBeetle doesn't even support variable-sized string type. You can store fixed-sized data, such as a string that's at most 32 bytes. What if the order information contains string longer than 32 bytes? Then you need to store that string in antoher database. TigerBeetle is not a general database. Static memory allocation doesn't fit most applicaitons.
The fallable allocation is useful in embedded system and OS development etc., but useless in common application programming, because OOM results in crash rather than failed allocaiton.
I'm always a bit surprised when people cite TigerBeetle for anything (Zig excellence, coding style, etc). They've made some unique choices that work great for them, but it really doesn't seem like they can be universally applied.
I'd bet only a small % of people praising TigerStyle actually disallow all runtime allocation in their own programs.
> The time to solve performance, and get the 1000x wins, is in the design phase, when you can't profile.
How does this make practical sense? I find it immensely easier to fix performance issues by profiling, benchmarking, finding hotspots. Things that weren't obviously performance bottlenecks during design become obvious when you profile.
Interesting write-up though. I haven't properly tried zig but I like reading these "initial impressions" style articles about it.
If you understand how the CPU, memory, network, and disk are processing your program and its structures, you can design your programs to optimize for the hardware.
This is also true for garbage collected languages, JavaScript in my case, but it requires a custom profiler and a bit more digging while asking better questions.
You'll have a more direct path towards better performance if the questions you're asking are closer to "how does a CPU work", and further away from "what hoops do I have to jump through in 2026 to avoid optimization bailouts after V8's latest round of changes"
True. The guide is an interesting read. When you are deep in the trenches, most of what the github link says is just common sense.
Eg: <
Optimize for the slowest resources first (network, disk, memory, CPU) in that order, after compensating for the frequency of usage, because faster resources may be used many times more. For example, a memory cache miss may be as expensive as a disk fsync, if it happens many times more.>
Yeah, except the CPUs are complex, you might not understand ALL the details of a working program (like randomising memory layout).
Plus not all speed-ups are made equal. Some speedups of a part of program can have no or even negative impact (as in making part of program faster slows down overall program execution).
No doubt, they are complex and you can't factor for everything, but I suspect that just even a cursory understanding of some broad characteristics across hardware will help you to design faster software when using a low-level language (and to some extent when using higher level languages as well), and your software will probably achieve must faster speeds than focusing on exotic design patterns in your software, for example.
The truth is really a middle ground and the fact that you won't get the design right the first time around until you have built that hardware programming experience and learned from past mistakes. But this statement doesn't make for a good marketing stunt.
While I don't agree TigerStyle inherently actually helps you with this, design and architectural mistakes don't usually get solved in the way you're describing. You sometimes have to rethink how to structure your entire codebase. Sometimes you can evolve an architectural improvement but sometimes it requires a complete rewrite and there's no way to get outside of that path dependency.
Most undergrad CS students go through an algorithms course and understand a bubble sort is inherently slower than a quick sort, no amount of optimization will get you past the fundamental n^2 time complexity. You can generalize those same analysis principles to whole architectures and distributed systems. If you don’t recognize that the server interactions your solution requires boils down to an n^2 algorithm, you’re in for a bad time. Unlike a function a live, deployed system is typically harder to evolve. Sometimes constraints like backwards compatibility are such that you simply can’t fix it.
There's a different between fixing performance mistakes, which tend to be obvious in profiling as big hotspots, and designing for maximum performance, which requires that you start, really, with the specification of what your application is doing, then follow that through to architecture and design with a strong view to reducing unnecessary work and staying within the operations that can be done at high speed with current systems.
If you’re already in your spec thinking about performance concerns at that level, then you can get pretty good performance in almost any language, though some languages might make it a little (lot) easier than others. But again I don’t think eg Zig vs Rust would be a big perf difference there.
I want your honest opinion on Zig, for dev or internal tools I always use Rust. Probably not because its the best choice for that project, but simply because its more popular. Same reason everyone uses React instead of things like Solid or Svelte that I find much better than React. Is it the same case with Zig as well?
> In Rust you can use ?, which is quicker than unwrap, but you also have to do something like Result<Type, Box<dyn std::error::Error>
No, you don't! When returning Result<T, E>, you can use ? on any Result<T2, E2> where E: From<E2>. In other words E doesn't have to be Box<dyn>, it just has to satisfy From<E2>.
Crates like thiserror make it easy to define your own error types that can be easily converted from all the other error types you can encounter in your functions! I do this whenever it doesn't make sense to use an inner error type directly, or whenever a function does its own validation that deserves its own error variant.
On top of that, I tend to also have error variants for each place in the function rather than only for each type of inner error. At error sites I do something like `.map_err(MyError::PlaceInTheFunction)?` rather than only `?`, and then errors become like a very efficient backtrace :)
While I'd push back against implying From<E2> is part of the crate, thiserror is an idiomatic approach these days, so I can understand the confusion. I can totally see how they could come to favor Zig if this behavior is "the default", as opposed to Rust where you'd usually see it done with "yet another library".
And so I see "the author's point" has another meaning now: that Zig-style errors are good :)
Edit: oh, after looking into Zig-style errors more, this is actually not how they work! They don't nest, they just exist in a global namespace, so they don't come with any location data themselves, but you can compose sets of them. Less powerful, but certainly more appealing to some :) I think out-parameters can be used as a side channel for error context.
Yeah I 1. wish they were properly composable and 2. think Rust would get less flak if these 'idiomatic' crates were just pulled into the standard library to avoid some of the dependency mayhem.
Zig's reimplementation of all of the standard libraries even though it's possible to use the existing ones is both baffling to me and kills usage of the implementation in my eyes.
Redoing critical parts such as crypto and compression is crazy in this day and age, hell they even have issues and merge requests open for issues that'd be headliners if found in any major language
Not just that, but on Windows, they're bypassing the actually guaranteed stable Win32 API in favor of linking directly to the lower-level components. Completely destroying any forward compatibility!
It's the kind of change that makes me read Zig as not trying to be a serious language. Not that there's anything wrong with that, but the way Zig positions itself is at odds with the completely bizarre takes they do.
>"The IO parameter is even more powerful, even if it is newer. It is well worth the breaking changes required to bring it about (even if I skipped the 0.15.0 -> 0.16.0 transition). In Zig, every function that interacts with the underlying operating system (with caveats) requires an "IO" parameter. This provides the context for input, output, and everything else.
Porting Zig to new operating systems is mostly just porting IO."
Nice!
(In Software Engineering, I think with this change, Zig nailed Separation Of Concerns: (https://en.wikipedia.org/wiki/Separation_of_concerns) aka modularity/modular design, at least with respect to handling the asymmetries of different OS's I/O APIs/syscalls - rather nicely!)
Why does everyone love being able to control the allocator in Zig? I rarely want this low level control over the allocator, I would rather have an easy to use interface to malloc/free (such as RAII) or would prefer the language push me to avoiding allocations when unnecessary. C and Zig users are always talking about how arena allocators are easier to use than the alternative but I disagree because the alternative is extremely easy to use when the language makes it so.
Arenas have a lot of footguns like growing out of control if you don't have space in your logic to delete them (e.g. suppose every new HTTP connection required obtaining a new allocation from the primary arena -- now you have a memory leak). They also aren't necessarily faster than malloc: I remember hearing a case where mimalloc was faster than an arena for a one-shot program like a linker because reclaiming space improved cache locality. Plus it's difficult to implement things like growable vectors or hashmaps using an arena without wasting space.
I just don't see how "futz about with the allocator constantly" and "use an arena" is actually a good default.
It is a good default for lib code because it makes that code truly re-usable. The same is true for great C libraries, they let you provide a block of memory instead of calling malloc inside. The library should not get to decide if/when allocations should be done.
In Zig app code you don't have to pass allocators all over if you don't want to, that's your code so do what you want. But for libraries it's the right thing to do because it puts the caller in control.
The reason you have to pass allocators instead of making this implicit like in e.g. Odin, is because Zig just takes a firm stance against implicit logic, firmer than any other language I've ever used. The end result is that people who like Zig tend to like passing allocators around even in their own code.
The library developer doesn't know what allocator will be passed, and the library user doesn't necessarily know how it will be used. They share an interface, so it will [probably] work, but it might not behave (mem/perf wise) as either expects. ArenaAllocators in particular don't play great with ArrayLists or nested ArenaAllocators.
I don't think it's a huge problem, but it's more subtle than an explicit allocator is a better because it provides more flexibility.
> Zig just takes a firm stance against implicit logic
I bought that as Zig's M.O., but then came the automatic "async/IO" colorless functions which is a huge chunk of implicit and hidden logic.
That's more implicit logic than what's in say JavaScript async AFAICT. Arbitrary int sizes with implicit casting rules, etc. More recently was the attempts of memory safety via an some sort of (optional) implicit GC mode. Personally I don't get it.
Are you sure you're up to date?
The async design changed multiple times, and the current approach is that of requiring passing an I/O interface that encapsulates the logic, same approach as for passing around an allocator.
This effectively makes all I/O bound code "quasi-async", and it's all explicit and the caller is in control.
That just means you haven't run into the problems yet that a global allocator brings with it. Other people have and welcome the better control over allocation provided by the Zig std library. The challenge is of course to balance convenience and flexibility. Also if you write code that prefers to not allocate in the first place (which should be the default), you're not affected anyway.
If you don't like arenas then that will push you towards avoiding allocations :)
I don't love malloc / free, managing frees one-to-one with allocations is a nightmare. An HTTP server is actually a great example of a good fit for arenas... you can have an arena created per connection, and then free the arena when the connection closes. Now all of your allocations during that connection are guaranteed to be freed instead of having to keep track of them individually. Need something to live across connections? Use the general purpose allocator for those particular things.
For one shot programs, why bother freeing anything at all? The gpa or malloc or whatever else is fine there.
Personally I mostly lean on fixed-size buffers, but if I'm writing Zig it's just little toy programs where blowing up when the buffer runs out of room is fine. But for big non-toy programs it might be good to use fixed-size buffers anyway and define your limits in terms of things actually relevant to your domain.
RAII and smart pointers are fine too, but C++ has you covered if you want those. Zig is specifically avoiding that kind of invisible code that destructors bring you.
> Now all of your allocations during that connection are guaranteed to be freed instead of having to keep track of them individually
And how do you size the arena?
> keep track of them individually
I think this is an exaggeration of the problem. This is what RAII semantics in C++ are for.
> avoiding that kind of invisible code
The invisible code is traded for defer statements right after initialization that are obvious and therefore mostly just noise, and also a problem if you forget to call them. This isn't an issue with RAII. I get the point of not wanting invisible code, but defers don't seem much of an improvement either. A trade-off at best.
> And how do you size the arena?
All HTTP servers have a configurable maximum request size. Ex: client_max_body_size in Nginx.
> And how do you size the arena?
Two options: you either say "eh 20MB per request ought to be big enough" and resize it later if you need to. Or you take time to figure out reasonable limits in terms of whatever domain you're dealing with, and return descriptive errors when those limits are exceeded. Maybe you're saying your service supports up to N HTTP headers and M query parameters in the URL and so on. For almost anything there's a limit you can place that's reasonable. Having no limits at all just means the limit is when you run out of memory / disk / whatever.
If you like RAII and C++ just use that though, Zig is an alternative not an upgrade, imo.
> This is what RAII semantics in C++ are for.
...which typically has more overhead than a good GC though and much more overhead than using arenas for lifetime management.
> If you don't like arenas then that will push you towards avoiding allocations
I mean push in the sense of a pit-of-success, not making me do things because the alternative is unpalatable.
> managing frees one-to-one with allocations is a nightmare
It really isn't a nightmare if your language has tools to help you. I'm never particularly concerned about frees in Rust outside of thinking about room to optimize.
> Need something to live across connections? Use the general purpose allocator for those particular things.
Well, this is a determination you have to make very carefully and if you screw it up (like in the situation I was trying to outline) you have a subtle bug.
> Personally I mostly lean on fixed-size buffers, but if I'm writing Zig it's just little toy programs where blowing up when the buffer runs out of room is fine.
What's also fine is using malloc, which will have perfectly reasonable performance for your toy programs.
This is reinforcing my belief that Zig programmers actually just have a sort of aesthetic attachment to the idea of managing their allocations themselves and this has very little to do with the actual practical concerns of writing software that works. I'm a lot more sympathetic to the other reply that talked about library code improving flexibility for those relying on the library, than this comment that only thinks about the case where everything goes perfectly and using a fixed size buffer for no reason.
> I'm never particularly concerned about frees in Rust outside of thinking about room to optimize.
Zig's position, love it or hate it, is that you should be thinking about it. Dropping a Vec<String> in Rust is O(n). Have you ever clicked the X on an app and it takes 10 seconds to disappear? Stuff like this is part of the problem. You shouldn't have to traverse your process's whole memory space just to call exit(0).
If you have to write that for loop, the O(n) will jump out at you and push you towards an arena or FixedBufferAllocator or std.process.cleanExit, or any other solution to avoid the loop.
Just to let you know, `std::process::exit(...)` in Rust does not call any destructors. C++ also has `std::quick_exit(...)`. Applications exiting slowly is a problem caused by app developers.
(There are cases where it also takes time because the OS does have to flush all open files during process teardown, etc., but this shouldn't generally be user-visible.)
Dropping vecs that contain strings does not make any Rust code in the real world slow. You would need to have a vec containing billions of strings, occupying several gigs of memory, before dropping such a structure took any perceptible amount of time. And for extreme cases like that, you can simply use arenas. The bumpalo crate is approximately as old as Zig is. The reason that people so rarely turn to arenas in Rust isn't because you can't do them, because you've always been able to, but rather because arenas are a very specific solution to a specific sort of memory access pattern, and going out of your way to strictly adhere to that pattern doesn't produce measurable differences for most software.
> This is reinforcing my belief that Zig programmers actually just have a sort of aesthetic attachment to the idea of managing their allocations themselves and this has very little to do with the actual practical concerns of writing software that works.
Indeed if you don't want to manage everything yourself I don't think there's a need to use Zig. The whole pitch is making everything explicit and not hiding control flow. And I do think that limits its usefulness to smaller-scale codebases.
Writing quality software doesn't require much from the programming language until your codebase gets very large and you're collaborating with a ton of people. If I'm expecting a codebase to grow to a large scale I'm not reaching for Zig for that. I don't trust _myself_ to keep that much Zig code tidy and correct let alone a big mob of developers and agents :)
Passing allocator pointers around has the advantage of allowing you to customize the allocator when you want, and to ignore it when you want (which is most of the time), i.e. just use the allocator you were given and pass it around like some piece of syntax or ctx in Go.
The trouble comes when you have data structures that manage memory, and you want to associate the allocation strategy with the particular instance of the data structure. Or, worse, you don't store the allocator pointer with the data and you require that all functions operating on the data structure happen to use compatible allocators.
At its simplest, though, passing allocators around is just removing an implicit global variable that is sometimes helpful to customize locally, but nearly impossible to customize locally if left as a global.
Allocators help solve the problem of "this code I want to use is almost good enough; how do I actually use it?"
I distinctly remember one of my first "real" jobs, somebody had written a C# library for GraphQL. It had some sort of bug or lack of functionality I had to fix. The author had fallen hook, line, and sinker for sealed classes and all that nonsense, so the shortest path to using the rest of their code was to fork the library and re-write the thousand offending lines and all references thereto. Luckily it wasn't a deep dependency.
Contrast that with similar issues in typical Python. The library likely accepts my favourite duck-typed solution, if it doesn't then I can likely work around it with an appropriate choice of dunder methods in the code I have interacting with the library, and if it still doesn't yield then I can just rewrite (monkey-patch) the offending code at runtime.
Not that either of those scenarios are objectively optimal, but they illustrate one of the principles people have in mind when they use an interface like allocators (not the only one, I'm sure other commentors will talk your ear off), that when push comes to shove you'd prefer to be able to use your existing code to solve your new problems. And that does empirically mostly work here; you can use nearly the entire Zig stdlib (especially when ignoring things like the posix namespace) and most of the rest of the ecosystem as well on embedded devices, in WASM, in bounded-memory applications, in generic application code, in fast-running CLI apps not even bothering to free, etc.
I agree with much of your discussion about arenas by the way. They're a moderately poor fit for the current interface in Zig, largely because the free functionality is questionable at best. IME, most uses of arenas actually know they need such a thing. Functions taking allocator arguments and expecting the allocator to be an arena should take an arena argument. When using arenas for lifetime management, something should probably own that arena rather than implicitly assuming whatever gets passed through the stack is correct. Passing arenas to arbitrary functions expecting general-purpose allocators is prone to leaks, and you'd be better off using the arena (or a buffer created therefrom) as a backing allocator for a data structure capable of actually freeing if you can't trust the implementation you're calling into (and if you can trust it, they should expose a better API allowing you to detect that trustability at the callsite).
If you had to pick a default, an arena allocator would definitely be it. Although even better would be a fixed-size arena that can never grow, like Tigerbeetle does.
I don't think the footguns you're talking about are real by the way.
arena's are popular in part because they are a way of grouping allocations by a single lifetime, reducing the amount of use-after-free's or double-free's that occur (reducing, not eliminating them).
they make a lot less sense in languages where the compiler or runtime takes care of this for you.
The biggest interesting thing to me about Zig is that is is a true spiritual successor to C.
mimalloc aggressively reclaims space and it benefits the use case in our Dip database built on rust.
This is for a long running process where consuming compute and memory should only occur on processing a request and must revert to a baseline memory consumption once the request is completed.
malloc with default allocator always gradually increases the memory consumption. This continues with enough request bursts on our testing until the process runs out of memory. mimalloc doesn't.
On mobile, we are stuck with the default allocator. On mobiles, the phenomenon of the default allocator consuming memory is reproducible even with normal Qt apps. It is what it is.
> This continues with enough request bursts on our testing until the process runs out of memory
Curious, how much memory and how many requests does that take to exhaust?
On the Odin vs Zig allocator bit:
In Zig you pass an allocator to every function that allocates, even if it doesn't make a lot of sense.
This rarely makes sense, as it's not really useful to append using a different allocator than you used previously.In Odin, allocators are passed in the init, stored as part of the struct and reused in the append.
That's just a matter of wrapping the allocator if you feel fhat is better approach. Question is, should there always be an allocator around with arr or do you want to split a build phase from an immutable use phase.
That's because in Zig that would be seen as a surprise side effect - the allocator is expected when the action is performed, not when it's "prepared", this way you know append() allocates. Otherwise it wouldn't be explicit which Array methods allocated.
The Odin way is useful, too. Depends on what you're building.
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The article says some Zig advantages but it's worth noting that all these advantages are tradeoffs.
Zig makes handling error easy but makes retaining error information hard. The result is that Zig developers either write more code than other languages to store diagnostic information, or just simply discard diagnostic information. The second makes it much harder to debug because the useful error information is discarded.
About the TigerStyle, it's worth noting that TigerBeetle doesn't even support variable-sized string type. You can store fixed-sized data, such as a string that's at most 32 bytes. What if the order information contains string longer than 32 bytes? Then you need to store that string in antoher database. TigerBeetle is not a general database. Static memory allocation doesn't fit most applicaitons.
The fallable allocation is useful in embedded system and OS development etc., but useless in common application programming, because OOM results in crash rather than failed allocaiton.
I'm always a bit surprised when people cite TigerBeetle for anything (Zig excellence, coding style, etc). They've made some unique choices that work great for them, but it really doesn't seem like they can be universally applied.
I'd bet only a small % of people praising TigerStyle actually disallow all runtime allocation in their own programs.
First I'm hearing of TigerStyle.
> The time to solve performance, and get the 1000x wins, is in the design phase, when you can't profile.
How does this make practical sense? I find it immensely easier to fix performance issues by profiling, benchmarking, finding hotspots. Things that weren't obviously performance bottlenecks during design become obvious when you profile.
Interesting write-up though. I haven't properly tried zig but I like reading these "initial impressions" style articles about it.
If you understand how the CPU, memory, network, and disk are processing your program and its structures, you can design your programs to optimize for the hardware.
Full guide for ref: https://github.com/tigerbeetle/tigerbeetle/blob/main/docs/TI...
This is also true for garbage collected languages, JavaScript in my case, but it requires a custom profiler and a bit more digging while asking better questions.
You'll have a more direct path towards better performance if the questions you're asking are closer to "how does a CPU work", and further away from "what hoops do I have to jump through in 2026 to avoid optimization bailouts after V8's latest round of changes"
True. The guide is an interesting read. When you are deep in the trenches, most of what the github link says is just common sense.
Eg: < Optimize for the slowest resources first (network, disk, memory, CPU) in that order, after compensating for the frequency of usage, because faster resources may be used many times more. For example, a memory cache miss may be as expensive as a disk fsync, if it happens many times more.>
This is just obvious common sense. Great read.
Yeah, except the CPUs are complex, you might not understand ALL the details of a working program (like randomising memory layout).
Plus not all speed-ups are made equal. Some speedups of a part of program can have no or even negative impact (as in making part of program faster slows down overall program execution).
No doubt, they are complex and you can't factor for everything, but I suspect that just even a cursory understanding of some broad characteristics across hardware will help you to design faster software when using a low-level language (and to some extent when using higher level languages as well), and your software will probably achieve must faster speeds than focusing on exotic design patterns in your software, for example.
The truth is really a middle ground and the fact that you won't get the design right the first time around until you have built that hardware programming experience and learned from past mistakes. But this statement doesn't make for a good marketing stunt.
While I don't agree TigerStyle inherently actually helps you with this, design and architectural mistakes don't usually get solved in the way you're describing. You sometimes have to rethink how to structure your entire codebase. Sometimes you can evolve an architectural improvement but sometimes it requires a complete rewrite and there's no way to get outside of that path dependency.
Most undergrad CS students go through an algorithms course and understand a bubble sort is inherently slower than a quick sort, no amount of optimization will get you past the fundamental n^2 time complexity. You can generalize those same analysis principles to whole architectures and distributed systems. If you don’t recognize that the server interactions your solution requires boils down to an n^2 algorithm, you’re in for a bad time. Unlike a function a live, deployed system is typically harder to evolve. Sometimes constraints like backwards compatibility are such that you simply can’t fix it.
There's a different between fixing performance mistakes, which tend to be obvious in profiling as big hotspots, and designing for maximum performance, which requires that you start, really, with the specification of what your application is doing, then follow that through to architecture and design with a strong view to reducing unnecessary work and staying within the operations that can be done at high speed with current systems.
And Zig doesn’t seem to help with most of that!
If you’re already in your spec thinking about performance concerns at that level, then you can get pretty good performance in almost any language, though some languages might make it a little (lot) easier than others. But again I don’t think eg Zig vs Rust would be a big perf difference there.
Pretty nice! I wrote a similar piece two years ago: https://blog.lohr.dev/after-a-day-of-programming-in-zig Great to see things are moving in the right direction.
I want your honest opinion on Zig, for dev or internal tools I always use Rust. Probably not because its the best choice for that project, but simply because its more popular. Same reason everyone uses React instead of things like Solid or Svelte that I find much better than React. Is it the same case with Zig as well?
I can't wait until Zig is a little more stable, I'd love to get into it more because the metaprogramming seems like such a draw.
I agree with anyzig, it's amazing.
I made a PR to add a default zig, which was rejected, I've been using it ever since though.
https://github.com/marler8997/anyzig/pull/71
Does ReTangled have anything to do with https://tangled.org?
it’s hyperlinked to the repo where you can see it has nothing to do with tangled
I know but the name is so sus
How much of the four months went to keeping up with breaking changes? Thats been my main blocker with zig, more than the language itself.
> In Rust you can use ?, which is quicker than unwrap, but you also have to do something like Result<Type, Box<dyn std::error::Error>
No, you don't! When returning Result<T, E>, you can use ? on any Result<T2, E2> where E: From<E2>. In other words E doesn't have to be Box<dyn>, it just has to satisfy From<E2>.
Crates like thiserror make it easy to define your own error types that can be easily converted from all the other error types you can encounter in your functions! I do this whenever it doesn't make sense to use an inner error type directly, or whenever a function does its own validation that deserves its own error variant.
On top of that, I tend to also have error variants for each place in the function rather than only for each type of inner error. At error sites I do something like `.map_err(MyError::PlaceInTheFunction)?` rather than only `?`, and then errors become like a very efficient backtrace :)
I think you're proving the author's point.
They're saying that you don't always have to return Result<T, Box<dyn Error>>, you can implement the From<Error> trait on the type and use ? as usual.
In other words implementing that trait lets you set a return type like Result<T, CustomAppError> use ? on it.
I think they're saying the author's point is that it's more fiddly in Rust (even if there are strong, well-regarded fiddles to use)
Yes, and your other part about the crate.
> There's also Zig-style composable errors with yet another library.
Ah, it's behind a link!
While I'd push back against implying From<E2> is part of the crate, thiserror is an idiomatic approach these days, so I can understand the confusion. I can totally see how they could come to favor Zig if this behavior is "the default", as opposed to Rust where you'd usually see it done with "yet another library".
And so I see "the author's point" has another meaning now: that Zig-style errors are good :)
Edit: oh, after looking into Zig-style errors more, this is actually not how they work! They don't nest, they just exist in a global namespace, so they don't come with any location data themselves, but you can compose sets of them. Less powerful, but certainly more appealing to some :) I think out-parameters can be used as a side channel for error context.
Yeah I 1. wish they were properly composable and 2. think Rust would get less flak if these 'idiomatic' crates were just pulled into the standard library to avoid some of the dependency mayhem.
I don't think errors are fiddly in rust. They're easy to compose.
Hey, I find it super easy and that's why I commented! By fiddly I just mean there are more steps/choices.
how so?
Sort of related from yesterday - https://news.ycombinator.com/item?id=50247203
(about zig's reimplementation of the libc, and some rough edges)
Zig's reimplementation of all of the standard libraries even though it's possible to use the existing ones is both baffling to me and kills usage of the implementation in my eyes.
Redoing critical parts such as crypto and compression is crazy in this day and age, hell they even have issues and merge requests open for issues that'd be headliners if found in any major language
Not just that, but on Windows, they're bypassing the actually guaranteed stable Win32 API in favor of linking directly to the lower-level components. Completely destroying any forward compatibility!
https://codeberg.org/ziglang/zig/issues/31131
It's the kind of change that makes me read Zig as not trying to be a serious language. Not that there's anything wrong with that, but the way Zig positions itself is at odds with the completely bizarre takes they do.
> Completely destroying any forward compatibility!
Microsoft breaking the ntdll.dll function interface is extremely unlikely, there's too much popular software in the wild depending on it.
From the link:
> > Won't this get flagged by anti-virus scanners as suspicious?
> Unfortunately, yes. We consider this a problem for the anti-virus scanners to solve.
I am suddenly less interested in relying on Zig.
Why should you design your software around what a different piece of software could claim of your program?
Because you want someone who trusts that different piece of software to use yours.
Zig's decision here now means the problem is _yours_ to convince this third party to trust you.
The next choice will be dynamically resolving syscall IDs from NTDLL? Surely that has no issues that could possibly happen.
zig users hate rust so much they found a way to make it 12,000x slower! incredible determination
(joking in case not obvious)
$curl: (6) Could not resolve host: gracefulliberty.com HN effect?
https://archive.is/gEZGz just in case
Legend!
>"The IO parameter is even more powerful, even if it is newer. It is well worth the breaking changes required to bring it about (even if I skipped the 0.15.0 -> 0.16.0 transition). In Zig, every function that interacts with the underlying operating system (with caveats) requires an "IO" parameter. This provides the context for input, output, and everything else.
Porting Zig to new operating systems is mostly just porting IO."
Nice!
(In Software Engineering, I think with this change, Zig nailed Separation Of Concerns: (https://en.wikipedia.org/wiki/Separation_of_concerns) aka modularity/modular design, at least with respect to handling the asymmetries of different OS's I/O APIs/syscalls - rather nicely!)
Anyway, very interesting article!
Related:
https://ziglang.org/download/0.16.0/release-notes.html#IO-as...
https://www.ziglang.in/learn/standard-library/io-interface/
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