Four years with Rust

Re:Four years with Rust by raphlinus on Wednesday December 21, 2016 @08:39PM (#13234126)

An exception (large complicated Rc-trees) is the rope in xi-editor. If you load a very large file, the operation of letting go of the last reference is potentially a large enough pause to have an effect on UI responsiveness. I've considered adding a mechanism that moves the object into a deallocation thread (or a deallocation task running in a thread pool) for this reason, although I'm not sure how important it is in the grand scheme of things.

In a GC'ed language such as Go, this would not be a problem. The flip-side is that I can safely and efficiently do updates in place, because Rust's reference counted type has a way to determine when you're holding the only reference.

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Re:Four years with Rust by MaulingMonkey on Thursday December 22, 2016 @02:58AM (#13235709)

> I've considered adding a mechanism that moves the object into a deallocation thread (or a deallocation task running in a thread pool) for this reason, although I'm not sure how important it is in the grand scheme of things.

The one time I've done this in C++, delayed deallocation actually made major loads/unloads worse for us on mass batch operations - more cache thrashing perhaps? Since this involved GPU resources, perhaps some bad interaction with the driver? I did keep around the "optimization" conditionally for smaller operations as this let us get rid of some hitching.

> In a GC'ed language such as Go, this would not be a problem.

In C# this traditionally manifested as lengthy GC pauses you had to jump through hoops to workaround. Modern GCs are much better these days, but it's not 100% solved.

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Re:Four years with Rust by xorxornop on Thursday December 22, 2016 @10:01AM (#13237624)

Hmm, yeah cache thrashing sounds a likely culprit - agreed. Perhaps before dropping all the references they should be sorted by memory address, so that page faults are minimised.

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