Diagnosing on CI since I can't repro locally even on my linux box

Author: ntjohnson1

pyproject.toml

@@ -197,6 +197,7 @@ dev = [
   "pyarrow>=19.0.0",
   "pygithub==2.5.0",
   "pytest-asyncio>=0.23.3",
+  "pytest-timeout>=2.3.1",
   "pytest>=7.4.4",
   "pyyaml>=6.0.3",
   "ruff>=0.15.1",

python/tests/test_pickle_multiprocessing.py

@@ -42,6 +42,7 @@
 
 import multiprocessing as mp
 
+import pytest
 from datafusion import col, lit
 
 from tests._pickle_multiprocessing_helpers import (
@@ -51,6 +52,12 @@
     register_udf_on_global_ctx,
 )
 
+# Hard upper bound for any single test in this module. If a spawn worker dies
+# silently during arg unpickling or initializer execution, ``Pool.map`` blocks
+# forever; ``pytest-timeout`` turns that into a real failure with a traceback
+# instead of a 30-minute job-level CI timeout.
+pytestmark = pytest.mark.timeout(60)
+
 
 def test_builtin_expr_through_multiprocessing_pool() -> None:
     """A built-in ``Expr`` survives a real ``multiprocessing.Pool`` dispatch."""