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The engine applies the query timeout and the per-query thread limit under the same per-connection lock that a running query holds for its whole duration. Connection.set_query_timeout() and set_max_threads_for_exec() called the engine right away, so with a query running on the connection they blocked until it finished. On the pybind backend they also held the GIL while waiting, which froze every Python thread, including an asyncio event loop that called AsyncConnection.set_query_timeout(). Both setters now record the value and return immediately. The value is applied before the next execute(), query_as_arrow() or Arrow-table call on that connection, by one thread at a time so that the latest value wins. The pybind bindings of the two native setters release the GIL, so a thread that does wait for the lock does not stall other threads. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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This work was produced with the help of language models.
The engine applies the query timeout and per-query thread limit under the mutex a running query holds for its whole duration, so
Connection.set_query_timeout()andset_max_threads_for_exec()blocked until the running query finished, and the pybind bindings held the GIL meanwhile, freezing every Python thread:AsyncConnection.set_query_timeout()with 4 long queries in flight froze the event loop for 12-13 s (CPython 3.13/3.14).Fix. Both setters record the value and return immediately; it is applied before the connection's next
execute(),query_as_arrow()or Arrow-table call, latest value wins. The two pybind bindings release the GIL, so a thread that does wait no longer stalls the others.Tests. Two new tests on a fresh connection: the setters return while a query runs (fails on
main: 6.05 s), and applying a pending setting while a query runs does not stall other threads (fails with the old bindings: 6.4 s stall). Both pass here on pybind and C-API. Full suites: no new failures.Fixes #63