Put repaint callback and tex manager behind separate mutexes #1389
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Do you have an idea of how these changes caused such an observable slow down in those specific test cases? Looking through the changes, I cannot see a clear cause for the slowdown. Note: I was unable to reproduce the slowdowns using |
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https://github.com/asny/three-d recently merged a PR adding `glow` support: asny/three-d#210 This means it is a prime candidate for embedding 3D painting inside an eframe app. There are currently a few kinks that need to be figured out: ### Black screen When reusing the same three_d context over time (as one should), we only get one frame of egui together with three_d, and then after that a black screen with just the three_d painting on top. I need to fix that before merging this PR. ### `Shape: Send + Sync` `Shape` is `Send + Sync` and `three_d::Context` is not. This means we cannot store a three_d context and send it to the `Shape::Callback`. So we either need to recreate the three_d context each frame (obviously a bad idea), or access it through a `thread_local` hack. This PR adds both as examples, with a checkbox to switch. We could consider making `Shape: !Send + !Sync`, but that would mean `egui::Context` could not be `Send+Sync` either (because the egui context stores shapes). This could actually be fine. `egui::Context` should only be used from a background thread for calling request_repaint and allocating textures. These could be made separate parts of the egui Context, so that one would do: ``` rust let repaint_signal = egui_ctx.repaint_signal(); let tex_mngr = egui_ctx.tex_mngr(); std::thread::spawn(move || { // We can use repaint_signal and tex_mngr here, // but NOT `egui_ctx`. }): Related: * #1379 * #1380 * #1389
emilk
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Mar 22, 2022
https://github.com/asny/three-d recently merged a PR adding `glow` support: asny/three-d#210 This means it is a prime candidate for embedding 3D painting inside an eframe app. There are currently a few kinks that need to be figured out: When reusing the same three_d context over time (as one should), we only get one frame of egui together with three_d, and then after that a black screen with just the three_d painting on top. I need to fix that before merging this PR. `Shape` is `Send + Sync` and `three_d::Context` is not. This means we cannot store a three_d context and send it to the `Shape::Callback`. So we either need to recreate the three_d context each frame (obviously a bad idea), or access it through a `thread_local` hack. This PR adds both as examples, with a checkbox to switch. We could consider making `Shape: !Send + !Sync`, but that would mean `egui::Context` could not be `Send+Sync` either (because the egui context stores shapes). This could actually be fine. `egui::Context` should only be used from a background thread for calling request_repaint and allocating textures. These could be made separate parts of the egui Context, so that one would do: ``` rust let repaint_signal = egui_ctx.repaint_signal(); let tex_mngr = egui_ctx.tex_mngr(); std::thread::spawn(move || { // We can use repaint_signal and tex_mngr here, // but NOT `egui_ctx`. }): Related: * #1379 * #1380 * #1389
This was referenced Mar 22, 2022
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Closes #1379
Please take a look @DusterTheFirst
This fattens up
Contextso that the repaint callback and texture manager can be used from any thread, even when you are not compiling with themulti_threadedfeature flag:This is one solution, but I'm not sure it is the best one.
The solution in this PR has the added advantage of mitigating #1380
Performance: the e2e tests shows very little change, but some specific tests (
Painter::rectandlabel format!) shows 10% slowdowns.I think the simpler solution is to remove the
single_threaded/multi_threadedfeatures and to always use proper mutexes, as proposed in: