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fix: set surface event before SetFormat to prevent draw thread deadlock #356

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Merged
winnerspiros merged 2 commits into from
May 23, 2026
Merged

fix: set surface event before SetFormat to prevent draw thread deadlock #356

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2dd8eeb
fix: set surface event before SetFormat to prevent draw thread deadlock
May 23, 2026
fb435de
fix: set surface event AFTER SetFormat to preserve draw thread invariant
May 23, 2026
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22 changes: 10 additions & 12 deletions osu.Android/OsuGameActivity.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -900,17 +900,20 @@ public void SurfaceChanged(ISurfaceHolder holder, global::Android.Graphics.Forma
Logger.Log(rgb565Message, LoggingTarget.Runtime, LogLevel.Important);
Logger.Log(rgb565Message, LoggingTarget.Performance, LogLevel.Important);

// Set the surface event BEFORE anything else so the draw thread can
// proceed with the current (soon-to-be-recreated) surface. Without this,
// the draw thread blocks on surfaceEvent.Wait(5000) and the native watchdog
// fires because no managed heartbeat arrives during the synchronous teardown.
// A brief frame or two with the old surface format is preferable to a
// deadlocked draw thread and watchdog kill.
surfaceEvent.Set();

// Tick the native watchdog BEFORE calling SetFormat. SetFormat triggers a
// synchronous surface teardown on the UI thread that can block for hundreds
// of milliseconds. During this window the Update thread may not get a chance
// to send a heartbeat (especially during startup when the runtime is under
// heavy load), and the native watchdog (10s default) would fire, killing the
// process and producing a black screen.
//
// Calling Heartbeat() here resets the watchdog timer from the UI thread,
// giving SetFormat time to complete without triggering a false positive.
// The native watchdog checks g_lastHeartbeatMonotonicSec which is updated
// by a simple atomic store — safe to call from any thread.
try
{
NativeWatchdog.Heartbeat();
Expand All @@ -921,6 +924,8 @@ public void SurfaceChanged(ISurfaceHolder holder, global::Android.Graphics.Forma
Debug.WriteLine($"[osu!] NativeWatchdog.Heartbeat failed (non-fatal): {e.Message}");
}

Debug.WriteLine("[osu!] Native surface format change requested (RGB565→RGBA8888)");

try
{
holder.SetFormat(global::Android.Graphics.Format.Rgba8888);
Expand All @@ -930,13 +935,6 @@ public void SurfaceChanged(ISurfaceHolder holder, global::Android.Graphics.Forma
Debug.WriteLine($"[osu!] Failed to request RGBA8888 format change for Vulkan: {e.Message}");
}

Debug.WriteLine("[osu!] Native surface format change requested (RGB565→RGBA8888)");

// Reset the surface event so GetSurfaceGlobalRef() does NOT unblock with the
// old (about-to-be-invalidated) surface handle. The event will be re-set when
// SurfaceChanged fires again for the new RGBA8888 surface.
surfaceEvent.Reset();

return;
}

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