bpo-28254: _posixsubprocess uses PyGC_Enable/PyGC_Disable

[vstinner]

https://bugs.python.org/issue28254

[vstinner]

cc @pablogsal @scoder

[pablogsal]

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FAIL: test_preexec_gc_module_failure (test.test_subprocess.POSIXProcessTestCase)
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Traceback (most recent call last):
  File "/home/runner/work/cpython/cpython/Lib/test/test_subprocess.py", line 2170, in test_preexec_gc_module_failure
    self.assertRaises(RuntimeError, subprocess.Popen,
AssertionError: RuntimeError not raised by Popen

👀

[vstinner]

Thanks. I fixed test_subprocess.

[scoder]

Actually, I think much of this could already have been saved before by using the ID-string API. But still, this is just so much better.

[vstinner]

Actually, I think much of this could already have been saved before by using the ID-string API. But still, this is just so much better.

I don't think that using cached interned strings is really relevant here, spawning a subprocess takes a few milliseconds, we are far from nanoseconds avoided thanks to the cache. Anyway, it's now gone ;-)

[gpshead]

yay, thanks for the cleanup!

[gpshead]

saving and restoring these two with the try: finally: seems no longer necessary now that they're not being monkeypatched out to cause errors. (harmless, but anyone reading this will wonder why...)

[vstinner]

Oh, you're right: I created #25709