support.args_from_interpreter_flags() adds -X uops

[vstinner]

No description provided.

[vstinner]

@gvanrossum: -X uops is not documented, is it on purpose?

With this change, the following tests will inherit -X uops as expected:

$ git grep -l args_from_interpreter_flags
Doc/library/test.rst
Lib/multiprocessing/forkserver.py
Lib/multiprocessing/resource_tracker.py
Lib/multiprocessing/spawn.py
Lib/multiprocessing/util.py
Lib/subprocess.py
Lib/test/bisect_cmd.py
Lib/test/libregrtest/worker.py
Lib/test/support/__init__.py
Lib/test/test_cmd_line_script.py
Lib/test/test_compileall.py
Lib/test/test_gdb/util.py
Lib/test/test_inspect.py
Lib/test/test_support.py
Tools/scripts/run_tests.py

Currently, it's only done manually in test_regrtest.py.

[gvanrossum]

I'm torn. I didn't know there was infrastructure for passing -X flags that could be easily extended. Then again I've not needed to run those tests with -Xuops. And when I want to run absolutely everything with -Xuops I use a one-line hack that turns it on by default.

It is not our intention that end users or even contributors (including most core devs) would ever need to pass -Xuops -- this is a temporary hack until we can enable the Tier 2 interpreter for everyone always. If anything, at that point we might have to provide a way to disable Tier 2 for some rare use cases (like we offered a way to revert to the old parser when we introduced the PEG parser, for one release). But what form that would take I don't know yet.

I have no idea how the code you're changing here works -- if you need it yourself I am fine with you merging this, but I don't feel comfortable approving the PR.

[vstinner]

I have no idea how the code you're changing here works -- if you need it yourself I am fine with you merging this, but I don't feel comfortable approving the PR.

Usually, regrtest tries to pass Python command line options of the first command (typed by the user) to worker processes. It's just convenient:

./python -X uops -m test test_sys -j1 runs ./python -X uops -m test.libregrtest.worker test_sys command with this change.

Without this change, -X uops is ignored and ./python -m test.libregrtest.worker test_sys is run instead.

I don't need this options. I'm not sure that I understand its purpose (since it's not documented ;-)). It's just that I was surprised to see a special code path for it in test_regtest, and only in test_regrtest.

If the option should not be passed to test worker processes, should the test_regrtest change be reverted? I'm talking about these lines:

    def run_python(self, args, **kw):
        extraargs = []
        if 'uops' in sys._xoptions:
            # Pass -X uops along
            extraargs.extend(['-X', 'uops'])
        args = [sys.executable, *extraargs, '-X', 'faulthandler', '-I', *args]

For this code, I chose to not use support.args_from_interpreter_flags() nor support.optim_args_from_interpreter_flags(). I prefer to control how tests are run. By the way, regrtest itself now adds options to Python when --fast-ci or --slow-ci option is used.

[gvanrossum]

You can look at the git history to see why I added that. I’m sure I needed it for something.

[gvanrossum]

In Brno I can explain the option.

[vstinner]

In short, I understand that this change is not desired, the current behavior is the expected behavior. Ok, I just close my issue. Thanks for the explanation.

[gvanrossum]

Thanks. Cross-reference: #108778