A scriptable fake dragonxd that reproduces, in minutes, the incident where
the GUI hard-killed a node busy with an hour-long witness rebuild:
- dragonxd's HTTP-RPC queue (8 workers + 16 queued, -rpcthreads /
-rpcworkqueue honoured): a full queue answers an immediate plain-text
500 "Work queue depth exceeded", and a request whose client gave up
keeps its slot until a worker reaches it
- a global cs_main held by a "witness rebuild" that logs the real
markers; every method except stop/help takes it
- warmup -28 with the daemon's allow-list, an optional startup replay
- dragonxd's shutdown order: stop (or SIGTERM on POSIX) unbinds RPC,
503s open connections, waits for the rebuild, then logs
"Shutdown: In progress..." / "Shutdown: done" and exits 0
Everything is appended to <datadir>/fake_dragonxd.events; a missing
"clean-exit" line means the process was killed. One portable C++17 file
(POSIX + Winsock), OFF by default (-DDRAGONX_BUILD_FAKE_DAEMON=ON), built
into <build>/fake_dragonxd/ so it can't shadow the real bin/dragonxd.
run-gui-with-fake.sh runs the GUI against it in a throwaway HOME.
Against master's GUI on Linux it reproduces the bug: closing during a
rebuild queues stop behind cs_main-blocked workers, then the GUI sends
SIGTERM and SIGKILL mid-rebuild, with no clean exit.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
DanSandClaude Opus 5.5
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