XWM clipboard transfer loop causes 100% CPU on one core

[janfeddersen-wq]

Hyprland's XWM module gets stuck in an infinite loop spamming [ERR] [xwm] No transfer with property data found, causing the
main Hyprland thread to consume 100% of one CPU core indefinitely.

The issue persists even after killing XWayland (kill -9 ), indicating the bug is in Hyprland's internal XWM state machine
rather than in XWayland itself. Only a full Hyprland restart resolves it.

How to reproduce

Unknown exact trigger. Occurred after normal usage with clipboard operations involving X11/XWayland applications. Using
cliphist + wl-paste for clipboard management.

Crash reports, logs, images, videos

Rolling log showing the spam:
[ERR] [xwm] No transfer with property data found
[ERR] [xwm] No transfer with property data found
[ERR] [xwm] No transfer with property data found
... (repeats indefinitely)

strace showing tight syscall loop (5 second sample):
% time seconds usecs/call calls errors syscall

---

24.24 0.119407 1 88039 85477 sendmsg
23.01 0.113379 1 88074 epoll_ctl
22.18 0.109266 1 85477 epoll_wait
15.92 0.078414 4 18510 ioctl
4.38 0.021569 1 17321 close
...
100.00 0.492654 1 333063 86826 total

Note: 85,477 sendmsg errors in 5 seconds - 97% failure rate, indicating a stuck retry loop.

Key observations:

• Main Hyprland thread (not a child thread) is at 100% CPU
• Killing XWayland does NOT stop the loop
• Clearing Wayland clipboard (wl-copy --clear) does NOT help
• No XWayland clients were running at the time of investigation

System Info

Hyprland 0.52.1 built from branch v0.52.1 at commit 967c3c7
Tag: v0.52.1

System: CachyOS Linux
Kernel: 6.17.9-2-cachyos

GPU: 3x NVIDIA RTX 3090
Driver: NVIDIA 580.105.08 (Open Kernel Module)

Monitors: 4x 2560x1440 (60Hz, 144Hz, 240Hz, 240Hz)

Libraries:

• Hyprgraphics: 0.4.0
• Hyprutils: 0.10.4
• Hyprcursor: 0.1.13
• Hyprlang: 0.6.6
• Aquamarine: 0.10.0

Suggested fix area

The XWM clipboard transfer handling in src/xwayland/ likely needs:

1. A retry limit or backoff for failed transfers
2. Proper cleanup when the transfer source is no longer valid
3. State reset when XWayland is killed/restarted

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