pythonbuf fix

[nickbridgechess]

Description

Fixes segfaults in multithreaded environments when using scoped_ostream_redirect.

The cause turns out to be the construction of a python str outside the GIL.

Recreate added to tests.

Suggested changelog entry:

Fixes segfaults in multithreaded environments when using scoped_ostream_redirect.

[YannickJadoul]

Great catch! Thanks!

Is this related to this weird occasional failure on Windows, perhaps, @henryiii? I can't immediately find the issue (or maybe there is none), but it's hinting into that direction.

[YannickJadoul]

A few things, but nothing drastic, so I'm fine with not having these done, as long as CI passes.

[nickbridgechess]

Any idea why some of the checks are failing? MSCV, for example, is complaining about unreachable code, and no object file being created... This is beyond me.

[YannickJadoul]

Any idea why some of the checks are failing? MSCV, for example, is complaining about unreachable code, and no object file being created... This is beyond me.

I don't think you're to blame, to be honest :-| Could this just be MSVC/VS 2015 tripping over it's own stdlib headers?
#77

[nickbridgechess]

Thanks for all your help on this. Is there anything else I need to do?

[YannickJadoul]

Thanks for all your help on this. Is there anything else I need to do?

I'm looking how to shut up MSVC. If you don't mind any of us pushing changes to your branch, then nope :-)

[nickbridgechess]

Thanks for all your help on this. Is there anything else I need to do?

I'm looking how to shut up MSVC. If you don't mind any of us pushing changes to your branch, then nope :-)

Do whatever you have to! LMK if you need anything from me.

[YannickJadoul]

Do whatever you have to! LMK if you need anything from me.

Great! Thanks a lot for the quick fixes, and for finding this in the first place! :-)

[YannickJadoul]

Windows tests just failed with the known fluke:

  _____________________________ test_multi_captured _____________________________
  
  capfd = <_pytest.capture.CaptureFixture object at 0x0000017DFE653508>
  
      def test_multi_captured(capfd):
          stream = StringIO()
          with redirect_stdout(stream):
              m.captured_output("a")
              m.raw_output("b")
              m.captured_output("c")
              m.raw_output("d")
          stdout, stderr = capfd.readouterr()
  >       assert stdout == "bd"
  E       AssertionError: assert '' == 'bd'
  E         - bd
  
  test_iostream.py:152: AssertionError
  ________________________________ test_redirect ________________________________
  
  capfd = <_pytest.capture.CaptureFixture object at 0x0000017DFE33F1C8>
  
      def test_redirect(capfd):
          msg = "Should not be in log!"
          stream = StringIO()
          with redirect_stdout(stream):
              m.raw_output(msg)
          stdout, stderr = capfd.readouterr()
  >       assert stdout == msg
  E       AssertionError: assert '' == 'Should not be in log!'
  E         - Should not be in log!
  
  test_iostream.py:169: AssertionError
  ______________________________ test_redirect_err ______________________________
  
  capfd = <_pytest.capture.CaptureFixture object at 0x0000017DFDF09108>
  
      def test_redirect_err(capfd):
          msg = "StdOut"
          msg2 = "StdErr"
      
          stream = StringIO()
          with redirect_stderr(stream):
              with m.ostream_redirect(stdout=False):
                  m.raw_output(msg)
                  m.raw_err(msg2)
          stdout, stderr = capfd.readouterr()
  >       assert stdout == msg
  E       AssertionError: assert '' == 'StdOut'
  E         - StdOut
  
  test_iostream.py:198: AssertionError

So this PR unfortunately does not fix them :-(

[YannickJadoul]

Finally, green! Good to merge, as far as I'm concerned! :-)

[YannickJadoul]

Thanks, @nickbridgechess! :-)

[nickbridgechess]

You're very welcome. I appreciate the help, and getting this fix in so quickly.
Great project - very useful and well written+designed.