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Show HN: A dynamic C (Hot reloading) module-based Web Framework
- dchristian 2y agoI keep wondering how this compares to Zig and WASM? Zig has a nicer syntax with fewer foot guns than C. It can also compile or link with C.
- warothia 2y agoIt would be really interesting if it was possible to use other languages which can be compiled to .so files. Will look into it!
- warothia 2y agoThis hobby project is inspired by kernel modules and AWS Lambda. It lets you write raw C modules, upload them, and have the server compile and run only the module itself at runtime—no need to recompile the entire application or restart the server. You can update routes and modules dynamically. Even WebSocket handlers can be updated without dropping existing connections.
- gwbas1c 2y agoImportant question: Why would anyone develop a web application in C? Typically web applications lean heavily on garbage collection and memory safety, because their bottlenecks are very rarely CPU/memory issues. The ROI on manually managing memory just isn't there for a typical web application.
- warothia 2y agoI could say speed, but the main reason for me is because it is fun. And I like to see what I can make C do. :D
- mst 2y ago"Because I can" remains an entirely legitimate reason for a hobby project. If anything, you've gone further along the "also (at least sort of) practical" scale than I expected. Given as mentioned elsewhere a per-request arena + bump allocator system, it might actually be -genuinely- practical (to the extent that writing application logic in C is at all ;) Bravo.
- warothia 2y agoThanks! Yes, an arena allocator for each request is on my todo list. Just didn’t get to implementing it yet. :D
- kaba0 2y agoThe second point is absolutely fair and your project is very cool and impressive, but the speed one is misleading. I am fairly sure you actually leave a fair bit of performance on the table simply by how convoluted parallelism and async IO are in C, and something like Java might easily outperform it in standard CRUD backend use cases.
- warothia 2y agoYou’re absolutely right, I have not tried very hard to optimize for speed either yet. To comment was more directed at the fact most just say that “speed” is the main reason to use C, but for me it’s almost exclusively for the fun and “cool” factor.
- SvenL 2y agoOn the other hand memory management in web applications is quite easy. Most of the stuff is only required for the lifetime of a request. Some stuff needs to be available the whole application life time.
- smt88 2y agoYou can do this with other languages (C# for example) as well. Memory is so cheap, though, that most companies should spend their money on increasing memory rather than on paying programmers to optimize memory usage.
- HexDecOctBin 2y agoCheap for whom? American programmers with FAANG salaries, or an under-funded third world NGO?
- kaba0 2y agoBoth. My phone could easily serve thousands of concurrent users.
- SvenL 2y agoYes, for most use cases it doesn’t really matter which language is chosen. Regarding just spending more money on memory - I agree that it’s definitely cheaper but it’s not only about wasting bytes of memory. If the garbage collector has a lot of work to do it may also impact response time/throughput. And yes, C# did a pretty good job with implementing mechanisms for reducing allocations on a language level. This definitely helps to reduce garbage collection.
- marginalia_nu 2y agoI don't think memory usage is the problem, but rather allocation costs and memory layout, i.e. performance. Serving web traffic simply isn't a very memory hungry task.
- Aurornis 2y agoLightweight web frameworks are great for embedded applications.
- gwbas1c 2y agoTake a few minutes to read through the use case. This isn't something that I would use for an embedded application. The fact that it allows uploading a compiled binary implies that it's for developing a web application in C, as opposed to merely adding a web endpoint to an embedded application.
- koito17 2y agoBack then, C was one of a few viable choices. The original implementation of the 2ch BBS was written in C.[0] Later revisions used Perl. Between 1998 and 2001, the site was a widely-used BBS and written in C. [0] https://github.com/nekoruri/readcgi https://github.com/nekoruri/readcgi
- williamcotton 2y ago> The ROI on manually managing memory just isn't there for a typical web application. You can use a per-request memory arena built with a simple bump allocator and then free the entire block when the request has been handled.
- kaba0 2y agoStill, why would I want to write C? Then use a script language with similar memory semantics, PHP started out exactly that way, if I'm not mistaken.
- _gabe_ 2y agoI’m all for using C for native development (and because I find it fun to work in occasionally), but I agree with your sentiment here. Not only do you have to manage memory manually, but you also have to do a lot more work for basic string manipulation which is the vast majority of web work. I would much rather work with a language with built in support for string manipulation and well known 3rd party libraries with good ergonomics for working with JSON, which a lot of your APIs will most likely be using.
- wwweston 2y agoSpeaking as someone who has done this back in the early wild days of the web: * if what you're vending is the software instead of the service (not what people usually do now, but there was a time), then this approach does provide for some obfuscation of IP and various secrets. * for some demand/resource profiles, CPU & memory issues are a lot easier to run into. The one I experienced with this project was targeting a serious e-commerce product to the context of 20-30 year old shared hosting environments (again, not what people would do now), but there may be different situational niches today. * familiarity. Sometimes you use what you know. And in the late 90s today's most popular web languages were still years away from being the convenient platform they'd become. The other popular options were Perl, maybe Java, possibly ColdFusion/VB/PHP. That said, you're correct: memory management was a pain, and by 2005 or so it was pretty clear that programmer cycles were as or more valuable than CPU and respectable frameworks were starting to coalesce in languages much better suited for string manipulation, so the ROI was not great. And of course, today you have other systems languages available like Go and Rust...
- smt88 2y ago> if what you're vending is the software instead of the service (not what people usually do now, but there was a time) I'm very curious what this means. Can you give an example?
- Philpax 2y agoGiving the client the executable to run, not running it for them. This means you can't hide the artifact from the client; for an interpreted language, this means recovery of the source code would be much easier than with a compiled output. That being said, it's still possible to reverse engineer the code; it just makes it harder.
- dsp_person 2y agoYou could also run a limited demo of your desktop application in a browser, where people have to pay to get access to the full thing.
- mariocesar 2y agoThe title "Hobby Project" makes the point right from the beginning
- lelanthran 2y ago> Typically web applications lean heavily on garbage collection and memory safety, because their bottlenecks are very rarely CPU/memory issues. I dunno about this assertion. Maybe it seems like the bottleneck is rarely CPU/memory when you're throwing 1GB RAM + dedicated instance at a webapp, but, for example Jenkins absolutely trashes any 1GB RAM instance because it runs out of RAM and/or CPU. My homegrown builder/runner CI/CD system, running the same `go build/test` commands, the same `git checkout` commands etc, written in C, peaks at a mere 60MB of RAM usage. I feel we are collectively underestimating just how much extra RAM is needed the popular languages that run a typical GC. [EDIT: I no longer even use my simple C app - I find a `make` cronjob for every 2m uses even less RAM, because there is no web interface anymore, I ssh into that machine to add new projects to the makefile]
- cv5005 2y agoGlobal warming. These days it should be considered immoral to write software that uses inefficient languages/runtimes/abstractions, we simply cannot afford to waste energy doing useless computations anymore.
- openasocket 2y agoCool! Looks like is used dynamic loading. Which is certainly workable. One downside is that while dynamic loading is well-supported, dynamic unloading is generally not. Meaning if you are using dynamic loading and re-loading for hot updates the server process will start to accumulate memory. Not a huge issue of the server process is periodically restarted, but can potentially cause weird bugs. You might be able to make something more robust by forking and loading the modules in a separate process. Then do something fancy with shared memory between the main process and the module processes. But I haven’t looked into this much
- warothia 2y agoOh really interesting, will look into it! Was afraid it would leak memory.
- mst 2y agoYou might not necessarily need even shared memory - it's possible to pass a file descriptor over a socket on all modern unices (and albeit with a completely different API also on Win32) so your control process could do an accept(), maybe read the headers in there, then talk to module processes to determine what the desired approach is, and then hand over the http socket so the module process can do whatever it needs to with it. When I imagine how I'd use this in my head the imagined design rapidly gets much more complicated than what you're currently doing, and I'm not at all arguing that that complexity is necessarily worth it ... but there's also all sorts of cool+weird things you could implement that way that would be exceedingly tricky otherwise, so I figured I'd point it out anyway :D (the example of code that does the relevant magic to get fds across a socket that immediately springs to mind is https://fastapi.metacpan.org/source/MLEHMANN/IO-FDPass-1.3/FDPass.xs https://fastapi.metacpan.org/source/MLEHMANN/IO-FDPass-1.3/F... - yes, warning, it's inside a perl extension, but I see no reason that would impede you borrowing the C parts if it was useful ;)
- warothia 2y agoInitially I did use fork a lot to allow each handler in its own “process” mainly because I wanted to isolate it as well in a container fashion. However the overhead became to much at the start when I just wanted it to work. Will be looking into it again!
- revskill 2y agoHow ti integrate with extermal library ?
- dakom 2y agoLove this :) Small, related anecdote: back in the year 2001 or so, this is in the same family of how I built websites... The difference is I wrote in in C as Apache Modules. So, like, most people were using other people's C modules (like PHP or CGI), but once you dug deeper and you wrote your logic/site _as_ a C module, it was so much more fun (and powerful too). I didn't have much of a templating language, so the answer to "can we change the text on this page?" was usually, "sure, just give me a few minutes to recompile the whole Apache server" :D Fun times
- warothia 2y agoFew others have brought up Apache Modules, and they are incredibly similar to my idea. :D Did not know about them while I was developing it. The main difference as far as I could see was the fact that you had to recompile / restart the server. Which I try to avoid, so little changes require almost no recompiling.
- incanus77 2y agoNah, you could just send a SIGHUP and not have to fully restart.
- warothia 2y agoOh! Did not know that, interesting. I guess they are more alike then.
- mst 2y agoIn apache 1.3 it was far from unusual to do a complete bundled compile and restart the entire thing every time because there were gremlins that showed up when you dynamically loaded the more complex modules often enough that it was operationally less aggravating overall to take the brute force approach (I did quite a bit of that a couple decades back, for my sins). apache 2+ is a very different (and rather more robust) beast, and also has the 'graceful restart' system - see https://httpd.apache.org/docs/2.4/stopping.html https://httpd.apache.org/docs/2.4/stopping.html - which makes the parent tell its worker processes to drain their request queues, -then- exit, after which each one is replaced in turn until you've fully upgraded to the new configuration+code. This approach has its disadvantages, of course, but not that morally different from how erlang processes hot reload into new code, and once you knew what you were doing the end result was simple, predictable, and nicely transparent to end users.
- Gollapalli 2y agoRad. Combine this with wasm on the front end and you’ve got full stack C web development.
- iso8859-1 2y agoCan you use dlopen in wasm already?