ResourceWarning: unclosed file with SAGE_DEBUG=yes

[vbraun]

Python 3 now emits a ResourceWarning if you use the quick'n dirty open(...).read() to read (or write) a file instead of a with context. This leads to lots and lots of test failures of the form:

File "src/doc/en/prep/Symbolics-and-Basic-Plotting.rst", line 487, in doc.en.prep.Symbolics-and-Basic-Plotting
Failed example:
    implicit_plot3d(p, (x, -r, r), (y, -r, r), (z, -r, r), plot_points=50, color='yellow')
Expected:
    Graphics3d Object
Got:
    doctest:warning
      File "/home/buildbot-sage/slave/sage_git/build/src/bin/sage-runtests", line 179, in <module>
        err = DC.run()
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/site-packages/sage/doctest/control.py", line 1238, in run
        self.run_doctests()
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/site-packages/sage/doctest/control.py", line 939, in run_do
ctests
        self.dispatcher.dispatch()
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/site-packages/sage/doctest/forker.py", line 2033, in dispat
ch
        self.parallel_dispatch()
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/site-packages/sage/doctest/forker.py", line 1925, in parall
el_dispatch
        w.start()  # This might take some time
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/site-packages/sage/doctest/forker.py", line 2200, in start
        super(DocTestWorker, self).start()
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/multiprocessing/process.py", line 112, in start
        self._popen = self._Popen(self)
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/multiprocessing/context.py", line 223, in _Popen
        return _default_context.get_context().Process._Popen(process_obj)
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/multiprocessing/context.py", line 277, in _Popen
        return Popen(process_obj)
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/multiprocessing/popen_fork.py", line 20, in __init__
        self._launch(process_obj)
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/multiprocessing/popen_fork.py", line 74, in _launch
        code = process_obj._bootstrap()
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/multiprocessing/process.py", line 297, in _bootstrap
        self.run()
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/site-packages/sage/doctest/forker.py", line 2172, in run
        task(self.options, self.outtmpfile, msgpipe, self.result_queue)
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/site-packages/sage/doctest/forker.py", line 2504, in __call
__
        doctests, extras = self._run(runner, options, results)
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/site-packages/sage/doctest/forker.py", line 2553, in _run
        result = runner.run(test)
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/site-packages/sage/doctest/forker.py", line 897, in run
        return self._run(test, compileflags, out)
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/site-packages/sage/doctest/forker.py", line 681, in _run
        self.compile_and_execute(example, compiler, test.globs)
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/site-packages/sage/doctest/forker.py", line 1123, in compil
e_and_execute
        exec(compiled, globs)
      File "<doctest doc.en.prep.Symbolics-and-Basic-Plotting[45]>", line 1, in <module>
        implicit_plot3d(p, (x, -r, r), (y, -r, r), (z, -r, r), plot_points=Integer(50), color='yellow')
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/site-packages/sage/repl/rich_output/display_manager.py", line 811, in displayhook
        plain_text, rich_output = self._rich_output_formatter(obj, dict())
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/site-packages/sage/repl/rich_output/display_manager.py", line 625, in _rich_output_formatter
        rich_output = self._call_rich_repr(obj, rich_repr_kwds)
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/site-packages/sage/repl/rich_output/display_manager.py", line 585, in _call_rich_repr
        return obj._rich_repr_(self)
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/site-packages/sage/interfaces/tachyon.py", line 138, in __call__
        open(modelfile,'w').write(model)
      File "/home/buildbot-sage/slave/sage_git/build/local/lib/python3.7/warnings.py", line 110, in _showwarnmsg
        msg.file, msg.line)
    :
    ResourceWarning: unclosed file <_io.TextIOWrapper name='/home/buildbot-sage/slave/sage_git/dot_sage/temp/zen/3222347/tmp_j8lfc7ax.dat' mode='w' encoding='UTF-8'>
    Graphics3d Object

Component: graphics

Author: Frédéric Chapoton

Branch/Commit: 1db03d6

Reviewer: Volker Braun

Issue created by migration from https://trac.sagemath.org/ticket/28833

[fchapoton]

Branch: u/chapoton/28833

[fchapoton]

Author: Frédéric Chapoton

[fchapoton]

Commit: 9c00054

[fchapoton]

comment:2

Here is a first tentative. I may have missed some.

---

New commits:

9c00054

trac 28833 adding a bunch of with open ... context managers

[sagetrac-git]

Branch pushed to git repo; I updated commit sha1. New commits:

1db03d6

trac 28833 fix doctests

[sagetrac-git]

Changed commit from 9c00054 to 1db03d6

[fchapoton]

comment:4

green bot

[vbraun]

comment:5

There are a couple of others, e.g. use

egrep -r 'open\([^)]*\)\.read' src/sage

but we can also postpone these for later if you rather want to merge the current state (please set to positive review in that case)

[fchapoton]

comment:6

Let us first merge this.

[fchapoton]

Reviewer: Volker Braun

[vbraun]

Changed branch from u/chapoton/28833 to 1db03d6