XFAIL TestLocalPath.test_make_numbered_dir_multiprocess_safe #11611
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hroncok force-pushed the xfail_test_make_numbered_dir_multiprocess_safe branch 2 times, most recently from c3a4e83 to 8f1f675 Compare 
nicoddemus reviewed Nov 13, 2023
hroncok force-pushed the xfail_test_make_numbered_dir_multiprocess_safe branch from 8f1f675 to c067bb3 Compare 
The tested py.path.local.make_numbered_dir function is *not* multiprocess safe, because is uses os.listdir which itself is not. The os.listdir documentation explicitly states that: > If a file is removed from or added to the directory during the call > of this function, whether a name for that file be included is unspecified. This can lead to a race when: 1. process A attempts to create directory N 2. the creation fails, as another process already created it in the meantime 3. process A calls listdir to determine a more recent maxnum 4. processes B+ repeatedly create newer directories and they delete directory N 5. process A doesn't have directory N or any newer directory in listdir result 6. process A attempts to create directory N again and raises For details, see pytest-dev#11603 (comment) and bellow. Additionally, the test itself has a race in batch_make_numbered_dirs. When this functions attempts to write to repro-N/foo, repro-N may have already been removed by another process. For details, see pytest-dev#11603 (comment) and bellow. --- The tested py.path.local.make_numbered_dir function is not used in pytest. There is a different implementation in _pytest.pathlib. We plan to remove this module eventually anyway. Closes pytest-dev#11603
hroncok force-pushed the xfail_test_make_numbered_dir_multiprocess_safe branch from c067bb3 to 052d145 Compare 
| I also amended the commit message not to say we will remove this function from 8.x. |
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The tested py.path.local.make_numbered_dir function is not multiprocess safe, because is uses os.listdir which itself is not.
The os.listdir documentation explicitly states that:
This can lead to a race when:
For details, see #11603 (comment) and bellow.
Additionally, the test itself has a race in batch_make_numbered_dirs. When this function attempts to write to repro-N/foo, repro-N may have already been removed by another process.
For details, see #11603 (comment) and bellow.
The tested py.path.local.make_numbered_dir function is not used in pytest. There is a different implementation in _pytest.pathlib.
We plan to remove this function in pytest 8.x.
Closes #11603