Rank variable not set in else statement for logging. (#451)

* rank variable not set in else statement for logging.

* Only call mpi get rank once

* Update changelog

docs/misc/changelog.rst

@@ -26,6 +26,7 @@ Bug Fixes:
   where OpenMPI would cause stable-baselines to hang on Ubuntu installs.
   See :ref:`installation notes <openmpi>` and
   `Issue #430 <https://github.com/hill-a/stable-baselines/issues/430>`.
+- Fix a bug when calling `logger.configure()` with MPI enabled (@keshaviyengar)
 
 Deprecations:
 ^^^^^^^^^^^^^

stable_baselines/logger.py

@@ -579,10 +579,11 @@ def configure(folder=None, format_strs=None):
         folder = os.path.join(tempfile.gettempdir(), datetime.datetime.now().strftime("openai-%Y-%m-%d-%H-%M-%S-%f"))
     assert isinstance(folder, str)
     os.makedirs(folder, exist_ok=True)
+    rank = mpi_rank_or_zero()
 
     log_suffix = ''
     if format_strs is None:
-        if mpi_rank_or_zero() == 0:
+        if rank == 0:
             format_strs = os.getenv('OPENAI_LOG_FORMAT', 'stdout,log,csv').split(',')
         else:
             log_suffix = "-rank%03i" % rank