WebGL context loss handling #5
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@@ -20,9 +20,15 @@ import { CHAR_DATA_ATTR_INDEX, CHAR_DATA_CODE_INDEX, CHAR_DATA_CHAR_INDEX, NULL_ | |
| import { IWebGL2RenderingContext } from './Types'; | ||
| import { INVERTED_DEFAULT_COLOR, DEFAULT_COLOR } from '../atlas/Types'; | ||
| import { RenderModel, COMBINED_CHAR_BIT_MASK } from './RenderModel'; | ||
| import { addDisposableDomListener } from '../../ui/Lifecycle'; | ||
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| export const INDICIES_PER_CELL = 4; | ||
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| interface IPendingRecover { | ||
| renderer: WebglRenderer; | ||
| justLost: boolean | ||
| } | ||
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| export class WebglRenderer extends EventEmitter implements IRenderer { | ||
| private _renderDebouncer: RenderDebouncer; | ||
| private _renderLayers: IRenderLayer[]; | ||
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@@ -39,10 +45,101 @@ export class WebglRenderer extends EventEmitter implements IRenderer { | |
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| private _isPaused: boolean = false; | ||
| private _needsFullRefresh: boolean = false; | ||
| private _salvaged: boolean = false; | ||
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| public dimensions: IRenderDimensions; | ||
| public colorManager: ColorManager; | ||
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| // Destroys paused renderes if the resources are needed for unpaused ones. | ||
| // This is unique to WebglRenderer because 'webgl2' contexts can become | ||
| // invalidated at any moment, typically by creating other canvases with | ||
| // 'webgl2' context, but also arbitrarily by the OS. | ||
| private static _contextHelper = new class { | ||
| private _recoverTimeout: any = null; | ||
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| // Terminals ordered by least-recently-used first | ||
| private _lru: ITerminal[] = []; | ||
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| // Renderers that lost context and need to be recreated | ||
| private _pendingRecover: IPendingRecover[] = []; | ||
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| // Called when a renderer is created or unpaused to signify that the user | ||
| // just used this terminal. Terminals are kept in least-recently-used order, | ||
| // so that if resources are needed, we can sacrifice the least important | ||
| // ones | ||
| public onRendererUnpaused(renderer: WebglRenderer) { | ||
| const index = this._lru.indexOf(renderer._terminal); | ||
| if (index >= 0) { | ||
| this._lru.splice(index, 1); | ||
| } | ||
| this._lru.push(renderer._terminal); | ||
| } | ||
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| public onRendererCreated(renderer: WebglRenderer) { | ||
| this.onRendererUnpaused(renderer); | ||
| } | ||
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| public onRendererDestroyed(renderer: WebglRenderer) { | ||
| const index = this._lru.indexOf(renderer._terminal); | ||
| this._lru.splice(index, 1); | ||
| } | ||
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| public recoverContext(renderer: WebglRenderer, justLost: boolean) { | ||
| this._pendingRecover.push({ renderer, justLost }); | ||
| if (!this._recoverTimeout) { | ||
| this._recoverTimeout = setTimeout(() => { | ||
| this._recoverTimeout = null; | ||
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| // webglcontextlost can fire before resize observer, which means that some | ||
| // of the renderers that are pending recovery, might not actually need it | ||
| // if they are now paused | ||
| const toRecover = this._pendingRecover.filter(({ renderer }) => !renderer._isPaused); | ||
| this._pendingRecover = []; | ||
| if (toRecover.length > 0) { | ||
| this._recoverPendingContexts(toRecover) | ||
| } | ||
| }, 0); | ||
| } | ||
| } | ||
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| private _recoverPendingContexts(toRecover: IPendingRecover[]) { | ||
| // try to kill some paused renderers to make room for this one | ||
| let killCount = 0; | ||
| for (let term of this._lru) { | ||
| const renderer = <WebglRenderer>term.renderer; | ||
| if (renderer._isPaused && !renderer._gl.isContextLost()) { | ||
| // Prevent this renderer from being immediately recreated when | ||
| // webglcontextlost fires | ||
| renderer.loseContext(); | ||
| renderer._salvaged = true; | ||
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| // Only kill enough renderers to recover all the pending contexts | ||
| killCount++; | ||
| if (killCount >= toRecover.length) { | ||
| break; | ||
| } | ||
| } | ||
| } | ||
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| // If any of these contexts were *just* lost, it means that we're currently | ||
| // at a resource limit, but if we failed to release any resources | ||
| // (i.e. everything is unpaused), there's no point in trying to recreate a | ||
| // renderer because we would be killing an unpaused one. In this case, | ||
| // just give up. | ||
| const requireKill = toRecover.some(({ justLost }) => justLost); | ||
| if (requireKill && killCount === 0) { | ||
| console.error('Too many simultaneous webgl contexts'); | ||
| return; | ||
| } | ||
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| // Recreate these renderer | ||
| toRecover.forEach(({ renderer }) => { | ||
| renderer._terminal.recreateRenderer() | ||
| }); | ||
| } | ||
| } | ||
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| constructor( | ||
| private _terminal: ITerminal, | ||
| theme: ITheme | ||
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@@ -87,6 +184,7 @@ export class WebglRenderer extends EventEmitter implements IRenderer { | |
| if (!this._gl) { | ||
| throw new Error('WebGL2 not supported'); | ||
| } | ||
| this.register(addDisposableDomListener(this._canvas, 'webglcontextlost', () => { this._onContextLost() })); | ||
| this._terminal.screenElement.appendChild(this._canvas); | ||
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| this._rectangleRenderer = new RectangleRenderer(this._terminal, this.colorManager, this._gl, this.dimensions); | ||
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@@ -95,22 +193,59 @@ export class WebglRenderer extends EventEmitter implements IRenderer { | |
| // Detect whether IntersectionObserver is detected and enable renderer pause | ||
| // and resume based on terminal visibility if so | ||
| if ('IntersectionObserver' in window) { | ||
| const observer = new IntersectionObserver(e => this._onIntersectionChange(e[0]), { threshold: 0 }); | ||
| observer.observe(this._terminal.element); | ||
| this.register({ dispose: () => observer.disconnect() }); | ||
| } | ||
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| WebglRenderer._contextHelper.onRendererCreated(this); | ||
| } | ||
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| public dispose(): void { | ||
| this._renderLayers.forEach(l => l.dispose()); | ||
| this._terminal.screenElement.removeChild(this._canvas); | ||
| super.dispose(); | ||
| this._canvas.width = 0; | ||
| this._canvas.height = 0; | ||
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| if (!this._gl.isContextLost()) { | ||
| console.log('Force context loss'); | ||
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There was a problem hiding this comment. This should happen automatically after dispose on the next GC? There was a problem hiding this comment. Yes, however, we force it so that another context can be created before the next GC. If we don't force it here, Chrome might not notice there's an available context and could kill an active one. What I observed is:
So, it seems like one of these is happening:
I'll grab a snapshot to make sure (3) is not happening There was a problem hiding this comment. I can confirm all webgl contexts are eventually GC'd. But we still need this to prevent Chrome from killing the oldest context (as opposed to the LRU one) |
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| this.loseContext(); | ||
| } | ||
| WebglRenderer._contextHelper.onRendererDestroyed(this); | ||
| } | ||
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| public loseContext(): void { | ||
| this._gl.getExtension('WEBGL_lose_context').loseContext() | ||
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There was a problem hiding this comment. Not supported in Chrome? https://developer.mozilla.org/en-US/docs/Web/API/WEBGL_lose_context/loseContext There was a problem hiding this comment. Nah, that seems outdated. It's definitely supported on Chrome and Chromium: https://codesandbox.io/embed/xpjjjmn1oq?view=preview |
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| } | ||
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| private _onContextLost(): void { | ||
| if (this._salvaged) { | ||
| this._salvaged = false; | ||
| return; | ||
| } | ||
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| WebglRenderer._contextHelper.recoverContext(this, true); | ||
| } | ||
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| private _onIntersectionChange(entry: IntersectionObserverEntry): void { | ||
| const wasPaused = this._isPaused; | ||
| this._isPaused = entry.intersectionRatio === 0; | ||
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| if (!this._isPaused) { | ||
| if (wasPaused) { | ||
| WebglRenderer._contextHelper.onRendererUnpaused(this); | ||
| } | ||
| if (this._gl.isContextLost()) { | ||
| WebglRenderer._contextHelper.recoverContext(this, false); | ||
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| // Return here because this renderer will be re-created to acquire a | ||
| // valid context, so there's no point in refreshing this one | ||
| return; | ||
| } | ||
| if (this._needsFullRefresh) { | ||
| this._terminal.refresh(0, this._terminal.rows - 1); | ||
| } | ||
| } | ||
| } | ||
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Could you pull this into WebglContextHelper.ts?