backend_pgf does not delete temp directories on Windows, changes the current directory

[cgohlke]

On Windows with mpl 1.2.0rc2, the following script successfully creates the figure but prints an error: could not delete tmp directory c:\users\...\temp\tmph2fo4m

import matplotlib
matplotlib.use('pgf')
from matplotlib import pyplot
pyplot.plot()
pyplot.savefig("test.pdf")

The backend_pgf fails to delete temporary directories because a latex process is started from the temporary directory. On Windows, directories and files can not be deleted while they are in use. The following code found in backend_pgf is also not thread safe:

tmpdir = tempfile.mkdtemp()
cwd = os.getcwd()
os.chdir(tmpdir)
...
self.print_pgf("figure.pgf")  # starts LatexManager in tmpdir
...
os.chdir(cwd)
shutil.rmtree(tmpdir)  # fails because LatexManager is still open in tmpdir

[pwuertz]

Ok, lets try giving LatexManager its own tmpdir...

[pwuertz]

By not thread safe you probably mean the use of os.chdir?

[pwuertz]

It seems that there is no direct way of fixing this on windows. Continuing the discussion in the referenced pull request.