Python 3.15 nogil fails with segmentation error

Thank you for the asyncpg!
I'm trying to use asyncpg with python 3.15t.
Got failure:
`
Fatal Python error: Segmentation fault

Thread 0x00007c94459fd6c0 [asyncio_0] (most recent call first):
File "/home/cas12/.local/share/uv/python/cpython-3.15.0b2+freethreaded-linux-x86_64-gnu/lib/python3.15t/concurrent/futures/thread.py", line 116 in _worker
File "/home/cas12/.local/share/uv/python/cpython-3.15.0b2+freethreaded-linux-x86_64-gnu/lib/python3.15t/threading.py", line 1160 in run
File "/home/cas12/.local/share/uv/python/cpython-3.15.0b2+freethreaded-linux-x86_64-gnu/lib/python3.15t/threading.py", line 1218 in _bootstrap_inner
File "/home/cas12/.local/share/uv/python/cpython-3.15.0b2+freethreaded-linux-x86_64-gnu/lib/python3.15t/threading.py", line 1180 in _bootstrap

Thread 0x00007c94461fe6c0 [OtelPeriodicExp] (most recent call first):
File "/home/cas12/.local/share/uv/python/cpython-3.15.0b2+freethreaded-linux-x86_64-gnu/lib/python3.15t/threading.py", line 367 in wait
File "/home/cas12/.local/share/uv/python/cpython-3.15.0b2+freethreaded-linux-x86_64-gnu/lib/python3.15t/threading.py", line 664 in wait
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/opentelemetry/sdk/metrics/_internal/export/init.py", line 520 in _ticker
File "/home/cas12/.local/share/uv/python/cpython-3.15.0b2+freethreaded-linux-x86_64-gnu/lib/python3.15t/threading.py", line 1160 in run
File "/home/cas12/.local/share/uv/python/cpython-3.15.0b2+freethreaded-linux-x86_64-gnu/lib/python3.15t/threading.py", line 1218 in _bootstrap_inner
File "/home/cas12/.local/share/uv/python/cpython-3.15.0b2+freethreaded-linux-x86_64-gnu/lib/python3.15t/threading.py", line 1180 in _bootstrap

Current thread 0x00007c944a0d5780 [python] (most recent call first):
File "/home/cas12/.local/share/uv/python/cpython-3.15.0b2+freethreaded-linux-x86_64-gnu/lib/python3.15t/asyncio/selector_events.py", line 1078 in write
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/asyncpg/connection.py", line 443 in _get_statement
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/asyncpg/connection.py", line 657 in _prepare
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/asyncpg/connection.py", line 638 in prepare
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 773 in _prepare
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 526 in _prepare_and_execute
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/sqlalchemy/util/_concurrency_py3k.py", line 196 in greenlet_spawn
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/sqlalchemy/ext/asyncio/session.py", line 758 in delete
File "/home/cas12/vscode/coffee_and_code/src/db/user_repository.py", line 1342 in delete_user
File "/home/cas12/vscode/coffee_and_code/src/service/user_service.py", line 102 in delete_user
File "/home/cas12/vscode/coffee_and_code/src/api/routers/admin.py", line 317 in delete_user
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/fastapi/routing.py", line 312 in run_endpoint_function
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/fastapi/routing.py", line 424 in app
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/fastapi/routing.py", line 105 in app
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/starlette/_exception_handler.py", line 42 in wrapped_app
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/fastapi/routing.py", line 119 in app
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/starlette/routing.py", line 290 in handle
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/starlette/routing.py", line 736 in app
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/starlette/routing.py", line 716 in call
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/fastapi/middleware/asyncexitstack.py", line 18 in call
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/starlette/_exception_handler.py", line 42 in wrapped_app
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/starlette/middleware/exceptions.py", line 63 in call
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/starlette/middleware/base.py", line 144 in coro
File "/home/cas12/.local/share/uv/python/cpython-3.15.0b2+freethreaded-linux-x86_64-gnu/lib/python3.15t/asyncio/events.py", line 94 in _run
File "/home/cas12/.local/share/uv/python/cpython-3.15.0b2+freethreaded-linux-x86_64-gnu/lib/python3.15t/asyncio/base_events.py", line 2066 in _run_once
File "/home/cas12/.local/share/uv/python/cpython-3.15.0b2+freethreaded-linux-x86_64-gnu/lib/python3.15t/asyncio/base_events.py", line 682 in run_forever
File "/home/cas12/.local/share/uv/python/cpython-3.15.0b2+freethreaded-linux-x86_64-gnu/lib/python3.15t/asyncio/base_events.py", line 711 in run_until_complete
File "/home/cas12/.local/share/uv/python/cpython-3.15.0b2+freethreaded-linux-x86_64-gnu/lib/python3.15t/asyncio/runners.py", line 127 in run
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pytest_asyncio/plugin.py", line 905 in inner
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/_pytest/python.py", line 166 in pytest_pyfunc_call
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pluggy/_callers.py", line 121 in _multicall
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pluggy/_manager.py", line 120 in _hookexec
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pluggy/_hooks.py", line 512 in call
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/_pytest/python.py", line 1720 in runtest
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pytest_asyncio/plugin.py", line 569 in runtest
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/_pytest/runner.py", line 179 in pytest_runtest_call
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pluggy/_callers.py", line 121 in _multicall
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pluggy/_manager.py", line 120 in _hookexec
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pluggy/_hooks.py", line 512 in call
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/_pytest/runner.py", line 245 in
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/_pytest/runner.py", line 353 in from_call
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/_pytest/runner.py", line 244 in call_and_report
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/_pytest/runner.py", line 137 in runtestprotocol
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/_pytest/runner.py", line 118 in pytest_runtest_protocol
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pluggy/_callers.py", line 121 in _multicall
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pluggy/_manager.py", line 120 in _hookexec
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pluggy/_hooks.py", line 512 in call
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/_pytest/main.py", line 396 in pytest_runtestloop
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pluggy/_callers.py", line 121 in _multicall
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pluggy/_manager.py", line 120 in _hookexec
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pluggy/_hooks.py", line 512 in call
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/_pytest/main.py", line 372 in _main
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/_pytest/main.py", line 318 in wrap_session
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/_pytest/main.py", line 365 in pytest_cmdline_main
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pluggy/_callers.py", line 121 in _multicall
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pluggy/_manager.py", line 120 in _hookexec
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/pluggy/_hooks.py", line 512 in call
File "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/_pytest/config/init.py", line 199 in main
File "/home/cas12/bin/pycharm-262.7581.27/plugins/python-ce/helpers/pycharm/_jb_pytest_runner.py", line 84 in

Current thread's C stack trace (most recent call first):
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python", at _Py_DumpStack+0x30 [0x4ae970]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x55d24b]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x55d0e6]
Binary file "/lib/x86_64-linux-gnu/libc.so.6", at +0x45f60 [0x7c9449e45f60]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python", at _PyCriticalSection_SuspendAll+0x7a [0x1addbba]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python", at PyEval_SaveThread+0x6e [0x1addb2e]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x1cb9a1e]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x1cb98b9]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x1cb9843]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x1a32e9e]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python", at _PyFunction_Vectorcall+0x380 [0x1a17cc6]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python", at PyObject_VectorcallMethod+0x12a [0x1a79cae]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/asyncpg/protocol/protocol.cpython-315t-x86_64-linux-gnu.so", at +0x33252 [0x7c944774f252]
**Binary file "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/asyncpg/protocol/protocol.cpython-315t-x86_64-**linux-gnu.so", at +0xa1ec3 [0x7c94477bdec3]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/asyncpg/protocol/protocol.cpython-315t-x86_64-linux-gnu.so", at +0xb0c33 [0x7c94477ccc33]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/asyncpg/protocol/protocol.cpython-315t-x86_64-linux-gnu.so", at +0x301c7 [0x7c944774c1c7]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/lib/python3.15t/site-packages/asyncpg/protocol/protocol.cpython-315t-x86_64-linux-gnu.so", at +0x4de48 [0x7c9447769e48]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x1db5732]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x1caca40]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x4b6f31]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x4b6d6e]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x4b7df0]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x4b7cc0]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x1b5de80]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x1a14cce]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python", at _PyFunction_Vectorcall+0x380 [0x1a17cc6]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x1afdbe6]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x1afd902]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python", at PyObject_Vectorcall+0x28b [0x1a3024b]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x1a2faef]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python", at _PyFunction_Vectorcall+0x380 [0x1a17cc6]
Binary file "/home/cas12/vscode/coffee_and_code/.venv/bin/python" [0x1afdbe6]

Extension modules: greenlet._greenlet, numpy._core._multiarray_umath, numpy.linalg._umath_linalg, _cffi_backend, cryptography.hazmat.bindings._rust, _brotli, psutil._psutil_linux, asyncpg.pgproto.pgproto, asyncpg.protocol.record, asyncpg.protocol.protocol, psycopg2._psycopg, cython.cimports.libc.math (total: 12)
`

首先，使用 Python 3.15t 和 asyncpg/connection.py 中所示的 asyncpg prepare 路径重现崩溃。检查 C 堆栈跟踪所涉及的 asyncpg 协议扩展，以及 delete/prepare 调用链；当所报告的操作在 free-threaded 解释器下不再导致 segmentation fault 时，即表示完成。