[ShubMishra]

Summary

• Disambiguate error 1347 using routine/table catalogs and SHOW AGGREGATES. Reject conflicting names before stopping the live server; keep non-replacing CREATE and published/other-session ownership checks.
• Move interactive UDF HTTP serving off the notebook event loop so synchronous same-kernel SQL calls can complete. Preserve context, startup errors, re-registration, cancellation, and graceful shutdown.
• Leave published UDF serving, notebook image pins, package version, and public APIs unchanged.

Test Plan

• Staging (user-provided evidence): both UDFs registered successfully; same-notebook SELECT pulse.double_it_sh_test(2.0); returned 4.0. Cell duration: 529 ms.
• Local: PYTHONASYNCIODEBUG=1 .venv/bin/python -m pytest -q -n 0 singlestoredb/tests/test_function_url.py singlestoredb/tests/test_udf_event_loop.py - 56 tests and 19 subtests passed on Python 3.11.12 / Uvicorn 0.34.3 against an isolated SingleStore 9.1.1 container. Covers actual 1347/1982/1050 responses, conflicting object types, case variants, schemas, and lifecycle behavior.
• Checks: changed-file pre-commit checks (including flake8/mypy) and git diff --check passed. Full engine-protocol suites were not run locally.

The pure-Python fallback warning is expected with SINGLESTOREDB_BUILD_EXTENSION=0; it did not prevent registration or invocation.

Runtime Impact

Interactive apps gain one persistent HTTP serving thread/event loop, not a new server thread per query. Startup/shutdown coordination is outside the request path; existing UDF dispatch remains unchanged. The new loop can own an executor for synchronous UDF work. Latency, throughput, and memory overhead have not been benchmarked; the screenshot is a functional smoke test.

Deployment Plan

• No shared staging/production image is changed by this PR or the manual runtime installation.
• After SDK review/release and remaining staging lifecycle checks, update the Helios notebook image's SDK pin in a separate rollout.
• Roll back the manual test by reinstalling the recorded prior SDK version/revision and restarting the kernel, or by recreating the disposable runtime from its unchanged image. A kernel restart alone does not restore the old package.
• Python cannot forcibly stop arbitrary synchronous UDF code. Shutdown stops the serving loop without waiting indefinitely for such worker code; the existing limitation on cancelling the user code itself remains.

JIRA Issues

Resolves MCDB-103581.

---

Note

Medium Risk
Changes interactive UDF server threading and registration preflight against the database catalog; incorrect conflict detection or shutdown could break notebook UDF registration or leave listeners open, though published UDF paths are unchanged.

Overview
Fixes same-kernel interactive Python UDF registration and invocation by serving HTTP on a dedicated thread (ThreadedUvicornServer) instead of the notebook asyncio loop, so synchronous SQL-in-notebook calls no longer deadlock the cell. Startup/shutdown now support both async tasks and thread Futures, including cleanup when startup fails or is cancelled, and updated docs that interactive shutdown may run from a different loop in the same kernel.

Interactive preflight now treats SHOW CREATE FUNCTION wrong-object (1347) as a possible name clash: it checks information_schema and SHOW AGGREGATES, raises a clear RuntimeError when the name is taken by a procedure/table/view/aggregate, and does not tear down the live UDF server when preflight fails. Free names still register with non-replacing CREATE.

Published UDF serving on the notebook loop is unchanged. Tests cover threaded lifecycle, context propagation, catalog conflicts, and integration against a real engine.

^{Reviewed by Cursor Bugbot for commit 1ad4347. Bugbot is set up for automated code reviews on this repo. Configure here.}

[Copilot]

🟡 Changes recommended

The unshielded startup cleanup wait allows a second cancellation to invalidate the server’s shared completion Future, causing errors during completion and subsequent shutdown or re-registration.

1 open issue

• Shield cleanup wait from cancellation to preserve completion Future · New

What changed in this PR

This PR fixes interactive Python UDF registration and allows synchronous SQL calls from the same notebook kernel by moving HTTP serving to a dedicated thread.

Changes:

• Treat error 1347 from SHOW CREATE FUNCTION as a missing function while preserving non-replacing registration.
• Add threaded interactive serving with startup and shutdown coordination; retain caller-loop serving for published UDFs.
• Expand regression tests for registration, same-kernel invocation, context propagation, and server lifecycle.

File	Description
singlestoredb/​tests/​test_function_url.py	Adds registration and threaded-server regression tests.
singlestoredb/​functions/​ext/​function_url.py	Recognizes WRONG_OBJECT during missing-function checks.
singlestoredb/​apps/​_uvicorn_util.py	Implements threaded serving and loop cleanup.
singlestoredb/​apps/​_python_udfs.py	Selects interactive threaded serving and coordinates its lifecycle.

_{Review effort: Balanced}

[Copilot]

🟢 Approval recommended

No active review issues block the interactive Python UDF registration and serving changes.

No open issues 🎉

1 resolved since last review

• Shield cleanup wait from cancellation to preserve completion Future

_{Review effort: Balanced}

[kesmit13]

Threaded serving looks solid; one real gap in the 1347 handling, plus two small items.

Also: the shutdown_udf_app docstring still says to call it "on the same event loop as run_udf_app", which no longer applies to the threaded server.

[cursor]

Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

^{Reviewed by Cursor Bugbot for commit ef78a7a. Configure here.}