multithreading_support(3)

📦 version 2.5.0, in fedora 43, fedora 44

💖 multithreading_support — Multithreading Support in Coin 💖

okay bestie, sit down, we're talking about multithreading_support(3) from the Coin Library Functions Manual and it's genuinely so much. no cap.

✨ DESCRIPTION ✨

so Coin's whole situation with using multiple threads — both in your application programs and inside the Coin library itself — comes down to two main features. two. that's it. let's get into it 🫶

🧵 feature one: the platform-independent thread classes

Coin hands you platform-independent thread-handling abstraction classes. like, classes the application programmer can freely use in her application code to start new threads, control their execution, work with mutexes, and do all the other tasks related to handling multiple threads. she can just... do it. iconic.

the classes in question are:

  • SbThread
  • SbMutex
  • SbStorage
  • SbBarrier
  • SbCondVar
  • SbFifo
  • SbThreadAutoLock
  • SbRWMutex
  • SbTypedStorage

see their respective documentation for the detailed information, okay? go read those, they're right there.

the way these classes fully hide the system-specific implementation?? obsessed. the implementation is either done on top of native Win32 (if on Microsoft Windows), or over POSIX threads (on UNIX and UNIX-like systems). you don't have to think about it. it just works. 💅

🔥 feature two: thread-safe rendering traversals

the other aspect of our multi-threading support is that Coin can be specially configured so that rendering traversals of the scene graph are done in a thread-safe manner. which means, like, e.g. it's possible to have Coin render the scene in parallel on multiple CPUs for multiple rendering pipes, to better take advantage of such high-end systems (like CAVE environments, for instance). main character energy fr fr.

⚠️ thread-safe render traversals are off by default, because there's a small overhead involved which would make rendering (very) slightly slower on single-threaded invocations. yes, "very" in parentheses. that's how slight it is. but still. off. by. default.

to get a Coin library built with thread-safe rendering, one must actively re-configure Coin and build a special, local version. for configure-based builds (UNIX and UNIX-like systems, or with Cygwin on Microsoft Windows) this is done with the option --enable-threadsafe to Autoconf configure. for how to change the configuration and re-build with Visual Studio, get in touch with us at coin-support@coin3d.org. they will help you, bestie, just email them 💌

🌸 RESTRICTIONS AND OTHER ISSUES 🌸

there are some restrictions and other issues which it is important to be aware of. pay attention, this is the vibe check:

  • we do not yet provide any support for binding the multi-threaded rendering support into the SoQt / SoWin / etc GUI bindings, and neither do we provide bindings against any specific library that handles multi-pipe rendering. this means the application programmer will have to possess some expertise, and put in some effort, to be able to utilize multi-pipe rendering with Coin. 😭 you got this though.
  • rendering traversals is currently the only operation which we publicly support to be thread-safe. there are other aspects of Coin that we know are thread-safe, like most other action traversals beside just rendering, but we make no guarantees in this regard. lowkey important.
  • be careful about using a separate thread for changing Coin structures versus what is used for the application's GUI event thread. 💀

we are aware of at least issues with Qt (and thereby SoQt), where you should not modify the scene graph in any way in a thread separate from the main Qt thread. this because it will trigger operations where Qt is not thread-safe. so like. don't do that. please. 🙈

🎀 SINCE 🎀

  • Coin 2.0

and that's the whole page, bestie! this one shipped with Coin, Version 2.5.0, and it's the multithreading_support(3) page from the Library Functions Manual. go forth and thread safely 💖✨🎀🦋🌸💅🫶👑🌈⭐

📦 where this page comes from