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matchfile Worker bug argument list too long when using matchfile to run many tests #139207
Description
Bug report
Bug description:
In #138313 (comment), I'm trying to select different subsets of test_importlib to determine which ones are implicated in the failures. Unfortunately, it seems that when extracting the list of tests and then passing that to --matchfile the execution fails with:
+ ./python -u -W error -bb -E -m test --fast-ci --junit-xml test-results.xml test_importlib --matchfile cases.txt --dont-add-python-opts Using random seed: 893560730 0:00:00 load avg: 0.54 Run 1 test in parallel using 1 worker process (timeout: 10 min, worker timeout: 15 min) Warning -- regrtest worker thread failed: Traceback (most recent call last): Warning -- File "/home/stan/cpython/Lib/test/libregrtest/run_workers.py", line 403, in run Warning -- mp_result = self._runtest(test_name) Warning -- File "/home/stan/cpython/Lib/test/libregrtest/run_workers.py", line 363, in _runtest Warning -- retcode, tmp_files = self.run_tmp_files(worker_runtests, Warning -- ~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^ Warning -- stdout_file.fileno()) Warning -- ^^^^^^^^^^^^^^^^^^^^^ Warning -- File "/home/stan/cpython/Lib/test/libregrtest/run_workers.py", line 299, in run_tmp_files Warning -- retcode = self._run_process(worker_runtests, Warning -- stdout_fd, tmp_dir) Warning -- File "/home/stan/cpython/Lib/test/libregrtest/run_workers.py", line 180, in _run_process Warning -- popen = create_worker_process(runtests, output_fd, tmp_dir) Warning -- File "/home/stan/cpython/Lib/test/libregrtest/worker.py", line 73, in create_worker_process Warning -- return subprocess.Popen(cmd, **kwargs) Warning -- ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^ Warning -- File "/home/stan/cpython/Lib/subprocess.py", line 1037, in __init__ Warning -- self._execute_child(args, executable, preexec_fn, close_fds, Warning -- ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Warning -- pass_fds, cwd, env, Warning -- ^^^^^^^^^^^^^^^^^^^ Warning -- ...<5 lines>... Warning -- gid, gids, uid, umask, Warning -- ^^^^^^^^^^^^^^^^^^^^^^ Warning -- start_new_session, process_group) Warning -- ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Warning -- File "/home/stan/cpython/Lib/subprocess.py", line 1969, in _execute_child Warning -- raise child_exception_type(errno_num, err_msg, err_filename) Warning -- OSError: [Errno 7] Argument list too long: '/home/stan/cpython/python' == Tests result: FAILURE, WORKER BUG ==
It seems there's a limit to the number of lines that can be passed to a --matchfile.
CPython versions tested on:
CPython main branch
Operating systems tested on:
Linux
Activity
nevin-lim commented on Oct 3, 2025
Hi there, my team and i would like to work on this issue if that is alright with you?
pythongh-139207: Pass regrtest worker configuration through a file