Added accumulation of loggers' metrics for the same steps (#1278)

* `add_argparse_args` method fixed (argument types added)

* autopep8 fixes

* --gpus=0 removed from test (for ci tests)

* Update pytorch_lightning/trainer/trainer.py

Co-Authored-By: Joe Davison <joe@huggingface.co>

* test_with_accumulate_grad_batches added

* agg_and_log_metrics logic added to the base logger class

* small format fix

* agg metrics strategies removed (not to complicate stuff)

* agg metrics: handle zero step

* autopep8

* changelog upd

* flake fix

* metrics aggregators factored out, metrics_agg.py added + tests

* metrics agg default value added

* Update pytorch_lightning/loggers/metrics_agg.py

Co-Authored-By: Jirka Borovec <Borda@users.noreply.github.com>

* metrics aggregators factored out, metrics_agg.py added + tests

* metrics agg default value added

* Update pytorch_lightning/loggers/metrics_agg.py

Co-Authored-By: Jirka Borovec <Borda@users.noreply.github.com>

* remove .item which causes sync issues (#1254)

* remove .item which causes sync issues

* fixed gradient acc sched

* fixed gradient acc sched

* test_metrics_agg.py removed (all tested in doctrings), agg metrics refactored

* test_metrics_agg.py removed (all tested in doctrings), agg metrics refactored

* autopep8

* loggers base.py types fixed

* test

* test

* metrics aggregation for loggers: each key now has a specific function (or default one)

* metrics aggregation for loggers: each key now has a specific function (or default one)

* docstrings upd

* manual typehints removed from docstrings

* batch_size decreased for test `test_with_accumulate_grad_batches`

* extend running accum

* refactor

* fix tests

* fix tests

* allowed_types generator scoped

* trainer.py distutils was imported twice, fixed

* TensorRunningAccum refactored

* TensorRunningAccum added to change log (Changed)

* change log pull link added

Co-authored-by: Joe Davison <joe@huggingface.co>
Co-authored-by: Jirka Borovec <Borda@users.noreply.github.com>
Co-authored-by: William Falcon <waf2107@columbia.edu>
Co-authored-by: J. Borovec <jirka.borovec@seznam.cz>

pytorch_lightning/trainer/logging.py

@@ -71,7 +71,7 @@ class TrainerLoggingMixin(ABC):
             step = step if step is not None else self.global_step
         # log actual metrics
         if self.proc_rank == 0 and self.logger is not None:
-            self.logger.log_metrics(scalar_metrics, step=step)
+            self.logger.agg_and_log_metrics(scalar_metrics, step=step)
             self.logger.save()
 
     def add_tqdm_metrics(self, metrics):