enricobuehler f4c3a5d0c3 fix(clients): shared-VkQueue race + swapchain recreate destroy-in-use — the intermittent device-lost stream killer ...

Live-diagnosed on the RTX box during the adaptive-bitrate A/B: 2 of 3 streams died
with VK_ERROR_DEVICE_LOST at stream start or at a mid-stream encoder rebuild, then
zombied — the demote-to-software path rebuilt the decoder against the same dead
device, FFmpeg wedged inside the rebuild, and the pump flushed a never-draining
backlog every 2 s forever. No OS TDR: the client's own Vulkan misuse. Two causes:

1. The presenter creates ONE graphics-family queue and hands FFmpeg's
   AVVulkanDeviceContext the same family (nb_graphics_queues=1 ⇒ queue 0) for its
   transfer/compute prep — so the pump thread and the presenter thread submitted to
   the SAME VkQueue with no shared lock, violating vkQueueSubmit's external-sync
   rule exactly when FFmpeg puts work on the graphics queue (decoder open /
   frames-context rebuild = stream start and every ABR encoder re-target). New
   guard-less QueueLock (FFmpeg's lock_queue/unlock_queue callbacks are a raw pair)
   shared by all four queue users: FFmpeg (callbacks installed via user_opaque),
   the presenter's submit/present/wait-idle, and the Skia overlay's flushes.

2. Swapchain recreation destroyed the old swapchain + render semaphores after ONE
   fence cycle — the fence proves our submit, not the presentation engine's
   semaphore consumption (VUID-vkDestroySemaphore-05149 +
   VUID-vkDestroySwapchainKHR-01282 on every recreate). Recreate now drains the
   queue (vkQueueWaitIdle under the shared lock — safe now that FFmpeg honours it)
   and destroys immediately; the deferred DisplayGarbage machinery is gone.

Resilience: VK_ERROR_DEVICE_LOST anywhere in a present error chain is now fatal —
the run loop fails the session loudly instead of demoting to software on a dead
device (the zombie path).

Verified on the RTX box (RTX 4090 → host .21) under VK_LAYER_KHRONOS_validation:
3/3 stream start/stop cycles clean, then 8 mid-stream encoder rebuilds in one
session (4 ABR down-steps under 10% induced loss + 4 clean-link recovery up-steps
— the exact scenarios that previously killed the device): 0 device losses, 0
wedges, both recreate VUIDs gone (previously fired on every path). Remaining
validation messages are FFmpeg's own video-session VUIDs, untouched by this
change. Linux: clippy -D warnings + tests green (home-worker-2).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

2026-07-09 12:42:11 +02:00

..

shaders

feat(video): HDR10/P010 end to end (phase 6)

2026-07-07 23:14:08 +02:00

src

fix(clients): shared-VkQueue race + swapchain recreate destroy-in-use — the intermittent device-lost stream killer

2026-07-09 12:42:11 +02:00

Cargo.toml

feat(clients/windows): single-window handoff, shared settings store, console-UI surfacing

2026-07-09 00:25:02 +02:00