importlinecacheimportconcurrent.futuresimportthreadingif__name__=="__main__":num_workers=20num_runs=100values=range(10,15)foriinvalues:withopen(f"test_{i}.py","w")ash:h.write("import time\n")h.write("import system\n")barrier=threading.Barrier(num_workers)defclosure():barrier.wait()for_inrange(num_runs):fornameinvalues:linecache.getline(f"test_{name}.py",1)withconcurrent.futures.ThreadPoolExecutor(max_workers=num_workers)asexecutor:futures= []foriinrange(num_workers):futures.append(executor.submit(closure))assertlen(list(f.result()forfinfutures))==num_workers

Traceback (most recent call last):  File "/project/playground/cpython_checks/linecache_race/repro.py", line 28, in <module>    assert len(list(f.result() for f in futures)) == num_workers               ~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  File "/project/playground/cpython_checks/linecache_race/repro.py", line 28, in <genexpr>    assert len(list(f.result() for f in futures)) == num_workers                    ~~~~~~~~^^  File "/tmp/cpython-tsan/lib/python3.14t/concurrent/futures/_base.py", line 443, in result    return self.__get_result()           ~~~~~~~~~~~~~~~~~^^  File "/tmp/cpython-tsan/lib/python3.14t/concurrent/futures/_base.py", line 395, in __get_result    raise self._exception  File "/tmp/cpython-tsan/lib/python3.14t/concurrent/futures/thread.py", line 86, in run    result = ctx.run(self.task)  File "/tmp/cpython-tsan/lib/python3.14t/concurrent/futures/thread.py", line 73, in run    return fn(*args, **kwargs)  File "/project/playground/cpython_checks/linecache_race/repro.py", line 22, in closure    linecache.getline(f"test_{name}.py", 1)    ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^  File "/tmp/cpython-tsan/lib/python3.14t/linecache.py", line 26, in getline    lines = getlines(filename, module_globals)  File "/tmp/cpython-tsan/lib/python3.14t/linecache.py", line 39, in getlines    return cache[filename][2]           ~~~~~^^^^^^^^^^KeyError: 'test_11.py'

import tracebackimport concurrent.futuresimport threadingif __name__ == "__main__":    num_workers = 20    num_runs = 100    barrier = threading.Barrier(num_workers)    def closure():        # import test_10        barrier.wait()        for _ in range(num_runs):            try:                raise RuntimeError("STOP")            except RuntimeError as e:                tb = traceback.extract_stack(e.__traceback__.tb_frame)    with concurrent.futures.ThreadPoolExecutor(max_workers=num_workers) as executor:        futures = []        for i in range(num_workers):            futures.append(executor.submit(closure))        assert len(list(f.result() for f in futures)) == num_workers

Traceback (most recent call last):  File "/project/playground/cpython_checks/linecache_race/repro_traceback.py", line 36, in closure    raise RuntimeError("STOP")RuntimeError: STOPDuring handling of the above exception, another exception occurred:Traceback (most recent call last):  File "/project/playground/cpython_checks/linecache_race/repro_traceback.py", line 44, in <module>    assert len(list(f.result() for f in futures)) == num_workers               ~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  File "/project/playground/cpython_checks/linecache_race/repro_traceback.py", line 44, in <genexpr>    assert len(list(f.result() for f in futures)) == num_workers                    ~~~~~~~~^^  File "/tmp/cpython-tsan/lib/python3.14t/concurrent/futures/_base.py", line 443, in result    return self.__get_result()           ~~~~~~~~~~~~~~~~~^^  File "/tmp/cpython-tsan/lib/python3.14t/concurrent/futures/_base.py", line 395, in __get_result    raise self._exception  File "/tmp/cpython-tsan/lib/python3.14t/concurrent/futures/thread.py", line 86, in run    result = ctx.run(self.task)  File "/tmp/cpython-tsan/lib/python3.14t/concurrent/futures/thread.py", line 73, in run    return fn(*args, **kwargs)  File "/project/playground/cpython_checks/linecache_race/repro_traceback.py", line 38, in closure    tb = traceback.extract_stack(e.__traceback__.tb_frame)  File "/tmp/cpython-tsan/lib/python3.14t/traceback.py", line 264, in extract_stack    stack = StackSummary.extract(walk_stack(f), limit=limit)  File "/tmp/cpython-tsan/lib/python3.14t/traceback.py", line 457, in extract    return klass._extract_from_extended_frame_gen(           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^        extended_frame_gen(), limit=limit, lookup_lines=lookup_lines,        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^        capture_locals=capture_locals)        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  File "/tmp/cpython-tsan/lib/python3.14t/traceback.py", line 508, in _extract_from_extended_frame_gen    f.line  File "/tmp/cpython-tsan/lib/python3.14t/traceback.py", line 377, in line    self._set_lines()    ~~~~~~~~~~~~~~~^^  File "/tmp/cpython-tsan/lib/python3.14t/traceback.py", line 355, in _set_lines    line = linecache.getline(self.filename, lineno).rstrip()           ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^  File "/tmp/cpython-tsan/lib/python3.14t/linecache.py", line 26, in getline    lines = getlines(filename, module_globals)  File "/tmp/cpython-tsan/lib/python3.14t/linecache.py", line 42, in getlines    return updatecache(filename, module_globals)  File "/tmp/cpython-tsan/lib/python3.14t/linecache.py", line 129, in updatecache    if len(cache[filename]) != 1:           ~~~~~^^^^^^^^^^KeyError: '/tmp/cpython-tsan/lib/python3.14t/concurrent/futures/thread.py'