[deepspeed] saving checkpoint fallback when fp16 weights aren't saved (#14948)

* [deepspeed] saving checkpoint fallback when fp16 weights aren't saved

* Bump required deepspeed version to match usage when saving checkpoints

* update version
Co-authored-by: Mihai Balint <balint.mihai@gmail.com>

setup.py

@@ -98,7 +98,7 @@ _deps = [
     "cookiecutter==1.7.2",
     "dataclasses",
     "datasets",
-    "deepspeed>=0.5.7",
+    "deepspeed>=0.5.9",
     "fairscale>0.3",
     "faiss-cpu",
     "fastapi",

src/transformers/dependency_versions_table.py

@@ -8,7 +8,7 @@ deps = {
     "cookiecutter": "cookiecutter==1.7.2",
     "dataclasses": "dataclasses",
     "datasets": "datasets",
-    "deepspeed": "deepspeed>=0.5.7",
+    "deepspeed": "deepspeed>=0.5.9",
     "fairscale": "fairscale>0.3",
     "faiss-cpu": "faiss-cpu",
     "fastapi": "fastapi",

src/transformers/trainer.py

@@ -2054,7 +2054,12 @@ class Trainer:
                 # now save the real model if stage3_gather_fp16_weights_on_model_save=True
                 # if false it will not be saved.
                 # This must be called on all ranks
-                self.deepspeed.save_fp16_model(output_dir, WEIGHTS_NAME)
+                if not self.deepspeed.save_fp16_model(output_dir, WEIGHTS_NAME):
+                    logger.warning(
+                        "deepspeed.save_fp16_model didn't save the model, since stage3_gather_fp16_weights_on_model_save=false. "
+                        "Saving the full checkpoint instead, use zero_to_fp32.py to recover weights"
+                    )
+                    self.deepspeed.save_checkpoint(output_dir)
 
         elif self.args.should_save:
             self._save(output_dir)