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renderer: vsync unfocused surfaces while dirty - #14068
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6ae1784 Unfocused surfaces stopped the CVDisplayLink and encoded a GPU frame on every PTY wakeup. A burst of close writes became that many Metal submits instead of one vsync. Keep the link running while the surface is visible and dirty or animating, whether or not it is focused. Idle surfaces still park. Focus continues to gate cursor blink, custom-shader animation, and QoS.
mitchellh
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Aug 30, 2026
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This actually makes sense to me.
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The installed app hard-froze on 2026-09-04: a render thread was stuck forever inside CVDisplayLinkStop (exposed by upstream's per-frame display-link parking, ghostty-org#14035/ghostty-org#14068), its 64-slot mailbox filled, and the app thread then blocked forever in occlusionCallback. - Keep the display link running while visible and stop it only on occlusion, and never call CVDisplayLinkStop on a link that is not running (deinit, loopExit). - Bound every app-thread push to the render mailbox (including the macOS display-id change) and the IO thread's resize push. After the first timeout the surface is marked wedged and later pushes fail fast instead of stalling the UI again. - Never lose state-carrying messages: undelivered visibility, focus, display, config and font-grid messages are kept and retried in order before the next push and on every render request, so a recovered render thread converges. Ownership of the config allocation and the font grid ref stays with the surface until delivered; the cell size is applied only once the renderer holds the new grid. - Closing a surface whose render thread is wedged detaches the thread and leaks the surface instead of joining it (embedded apprt), so a dead tab can be closed without hanging the app.
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A follow on for #14035, we can now fix a long standing effiency/performance bug now that we park the display link while idle. This actually could cause "animated" un-focused windows to use more GPU than their focused counterparts. (AI Agent interfaces seem to love animation).
6ae1784
Unfocused surfaces stopped the CVDisplayLink and encoded a GPU frame on every PTY wakeup. A burst of close writes became that many Metal submits instead of one vsync.
Keep the link running while the surface is visible and dirty or animating, whether or not it is focused. Idle surfaces still park.