New submission from Mustafa Quraish <mustafaqura...@gmail.com>:
The code attached produces weird behaviour on macOS (Catalina at least) on Python3.8 / Python3.9. Issue has been reproduced on at least one other mac belonging to a friend. Does not occur on Linux as far as I have tested. I have simplified the code as much as I can, so the example attached does not actually need to use parallelism. Code description: Read text from a file, change directory using `os.chdir`, spawn 5 processes and pass the `print` function as the handler along with the text. Expectation: File contents should be printed 5 times Result: Code tries to load (again) the file in each thread, but fails since the directory was changed. Precondition: Have `file.txt` in the same directory containing some text Output when run on Python3.7, I get the following (expected output): ``` Reading file... Text loaded was: 'file contents' file contents file contents file contents file contents file contents ``` When running on 3.8 / 3.9 (on a mac) I get the following: ``` Reading file... Text loaded was: 'file contents' Error: /Users/mustafa/dev/ptest/test_dir/file.txt does not exist. Error: /Users/mustafa/dev/ptest/test_dir/file.txt does not exist. Error: /Users/mustafa/dev/ptest/test_dir/file.txt does not exist. ``` It seems to me that even opened `file.txt` is loaded in the main thread and text is read from it, this value isn't passed into the spawned processes and they are calling `load()` again (which is where the error message is produced). ---------- components: macOS files: test.py messages: 380483 nosy: bquinlan, mustafaquraish, ned.deily, pitrou, ronaldoussoren priority: normal severity: normal status: open title: Inconsistent ProcessPoolExecutor behaviour on macOS between 3.7 and 3.8/9 type: behavior versions: Python 3.8 Added file: https://bugs.python.org/file49579/test.py _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue42281> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com