[DeepSpeed] restore memory for evaluation (#10114)

* free up memory at the end of train

* rework tests

* consistent formatting

* correction

examples/tests/deepspeed/ds_config.json

@@ -7,40 +7,37 @@
         "min_loss_scale": 1
     },
 
-   "zero_optimization": {
-       "stage": 2,
-       "allgather_partitions": true,
-       "allgather_bucket_size": 2e8,
-       "overlap_comm": true,
-       "reduce_scatter": true,
-       "reduce_bucket_size": 2e8,
-       "contiguous_gradients": true,
-       "cpu_offload": true
-   },
+    "zero_optimization": {
+        "stage": 2,
+        "allgather_partitions": true,
+        "allgather_bucket_size": 2e8,
+        "overlap_comm": true,
+        "reduce_scatter": true,
+        "reduce_bucket_size": 2e8,
+        "contiguous_gradients": true,
+        "cpu_offload": true
+    },
 
-   "zero_allow_untested_optimizer": true,
+    "zero_allow_untested_optimizer": true,
 
-   "optimizer": {
-     "type": "AdamW",
-     "params": {
-       "lr": 3e-5,
-       "betas": [
-         0.8,
-         0.999
-       ],
-       "eps": 1e-8,
-       "weight_decay": 3e-7
-     }
-   },
+    "optimizer": {
+        "type": "AdamW",
+        "params": {
+            "lr": 3e-5,
+            "betas": [0.8, 0.999],
+            "eps": 1e-8,
+            "weight_decay": 3e-7
+        }
+    },
 
-   "scheduler": {
-     "type": "WarmupLR",
-     "params": {
-       "warmup_min_lr": 0,
-       "warmup_max_lr": 3e-5,
-       "warmup_num_steps": 500
-     }
-   },
+    "scheduler": {
+        "type": "WarmupLR",
+        "params": {
+            "warmup_min_lr": 0,
+            "warmup_max_lr": 3e-5,
+            "warmup_num_steps": 500
+        }
+    },
 
     "steps_per_print": 2000,
     "wall_clock_breakdown": false

examples/tests/deepspeed/test_deepspeed.py

@@ -17,8 +17,14 @@ import os
 import unittest
 
 from transformers.integrations import is_deepspeed_available
-from transformers.testing_utils import TestCasePlus, execute_subprocess_async, require_torch_multi_gpu
-from transformers.trainer_callback import TrainerState
+from transformers.testing_utils import (
+    TestCasePlus,
+    execute_subprocess_async,
+    get_gpu_count,
+    require_torch_gpu,
+    require_torch_multi_gpu,
+    slow,
+)
 from transformers.trainer_utils import set_seed
 
 
@@ -42,37 +48,45 @@ def require_deepspeed(test_case):
         return test_case
 
 
+@slow
 @require_deepspeed
+@require_torch_gpu
 class TestDeepSpeed(TestCasePlus):
-
-    # XXX: need to do better validation beyond just that the run was successful
-    def run_quick(self, distributed=None, extra_args_str=None, remove_args_str=None):
-        output_dir = self.run_trainer(1, "12", MBART_TINY, 1, distributed, extra_args_str, remove_args_str)
-        logs = TrainerState.load_from_json(os.path.join(output_dir, "trainer_state.json")).log_history
-        eval_metrics = [log for log in logs if "eval_loss" in log.keys()]
-        first_step_stats = eval_metrics[0]
-        assert "eval_bleu" in first_step_stats
-
-    def run_quick_no_train(self, distributed=None, extra_args_str=None):
-        remove_args_str = "--do_train"
-        output_dir = self.run_trainer(1, "12", MBART_TINY, 1, distributed, extra_args_str, remove_args_str)
-        val_metrics = load_json(os.path.join(output_dir, "val_results.json"))
-        assert "val_bleu" in val_metrics
-        test_metrics = load_json(os.path.join(output_dir, "test_results.json"))
-        assert "test_bleu" in test_metrics
-
     @require_torch_multi_gpu
-    def test_basic(self):
-        self.run_quick()
+    def test_basic_distributed(self):
+        self.run_quick(distributed=True)
 
     @require_torch_multi_gpu
     def test_grad_acum(self):
-        self.run_quick(extra_args_str="--gradient_accumulation_steps 2")
+        self.run_quick(distributed=True, extra_args_str="--gradient_accumulation_steps 2")
 
-    @require_torch_multi_gpu
-    def test_no_train(self):
+    def test_do_eval_no_train(self):
         # we should not fail if train is skipped
-        self.run_quick_no_train()
+        output_dir = self.run_trainer(
+            eval_steps=1,
+            max_len=12,
+            model_name=MBART_TINY,
+            num_train_epochs=1,
+            distributed=False,
+            extra_args_str="--do_eval",
+            remove_args_str="--do_train",
+        )
+        val_metrics = load_json(os.path.join(output_dir, "val_results.json"))
+        assert "val_bleu" in val_metrics
+
+    # XXX: need to do better validation beyond just that the run was successful
+    def run_quick(self, distributed=True, extra_args_str=None, remove_args_str=None):
+        output_dir = self.run_trainer(
+            eval_steps=1,
+            max_len=12,
+            model_name=MBART_TINY,
+            num_train_epochs=1,
+            distributed=distributed,
+            extra_args_str=extra_args_str,
+            remove_args_str=remove_args_str,
+        )
+        train_metrics = load_json(os.path.join(output_dir, "train_results.json"))
+        assert "train_runtime" in train_metrics
 
     def run_trainer(
         self,
@@ -80,7 +94,7 @@ class TestDeepSpeed(TestCasePlus):
         max_len: str,
         model_name: str,
         num_train_epochs: int,
-        distributed: bool = False,
+        distributed: bool = True,
         extra_args_str: str = None,
         remove_args_str: str = None,
     ):
@@ -97,18 +111,13 @@ class TestDeepSpeed(TestCasePlus):
             --max_target_length {max_len}
             --val_max_target_length {max_len}
             --do_train
-            --do_eval
-            --do_predict
             --num_train_epochs {str(num_train_epochs)}
             --per_device_train_batch_size 4
-            --per_device_eval_batch_size 4
             --learning_rate 3e-3
             --warmup_steps 8
-            --evaluation_strategy steps
             --predict_with_generate
             --logging_steps 0
             --save_steps {str(eval_steps)}
-            --eval_steps {str(eval_steps)}
             --group_by_length
             --label_smoothing_factor 0.1
             --adafactor
@@ -116,7 +125,6 @@ class TestDeepSpeed(TestCasePlus):
             --tgt_lang ro_RO
             --src_lang en_XX
         """.split()
-        # --eval_beams  2
 
         if extra_args_str is not None:
             args.extend(extra_args_str.split())
@@ -126,12 +134,13 @@ class TestDeepSpeed(TestCasePlus):
             args = [x for x in args if x not in remove_args]
 
         ds_args = f"--deepspeed {self.test_file_dir_str}/ds_config.json".split()
-        distributed_args = f"""
-            {self.test_file_dir}/../../seq2seq/finetune_trainer.py
-        """.split()
-        cmd = ["deepspeed"] + distributed_args + args + ds_args
+        script = [f"{self.examples_dir_str}/seq2seq/finetune_trainer.py"]
+        num_gpus = get_gpu_count() if distributed else 1
+        launcher = f"deepspeed --num_gpus {num_gpus}".split()
+
+        cmd = launcher + script + args + ds_args
         # keep for quick debug
-        # print(" ".join(cmd)); die
+        # print(" ".join([f"PYTHONPATH={self.src_dir_str}"] +cmd)); die
         execute_subprocess_async(cmd, env=self.get_env())
 
         return output_dir

src/transformers/trainer.py

@@ -17,6 +17,7 @@ The Trainer class, to easily train a 🤗 Transformers from scratch or finetune
 """
 
 import collections
+import gc
 import inspect
 import math
 import os
@@ -266,8 +267,9 @@ class Trainer:
 
         # postpone switching model to cuda when:
         # 1. MP - since we are trying to fit a much bigger than 1 gpu model
-        # 2. fp16-enabled DeepSpeed loads the model in half the size and it doesn't need .to() anyway
-        if not (self.is_model_parallel or args.deepspeed):
+        # 2. fp16-enabled DeepSpeed loads the model in half the size and it doesn't need .to() anyway,
+        #    and we only use deepspeed for training at the moment
+        if not self.is_model_parallel and not (args.deepspeed and args.do_train):
             model = model.to(args.device)
 
         # Force n_gpu to 1 to avoid DataParallel as MP will manage the GPUs
@@ -817,7 +819,7 @@ class Trainer:
 
         # important: at this point:
         # self.model         is the Transformers Model
-        # self.model_wrapped is DDP(Transformers Model), DDP(Deepspeed(Transformers Model)), etc.
+        # self.model_wrapped is DDP(Transformers Model), Deepspeed(Transformers Model), etc.
 
         # Train!
         if is_torch_tpu_available():
@@ -1036,6 +1038,14 @@ class Trainer:
         # add remaining tr_loss
         self._total_loss_scalar += tr_loss.item()
 
+        if self.deepspeed:
+            # free up any memory that might be useful for eval
+            self.deepspeed = None
+            self.optimizer = None
+            self.lr_scheduler = None
+            self.model_wrapped = self.model
+            gc.collect()  # force memory release
+
         return TrainOutput(self.state.global_step, self._total_loss_scalar / self.state.global_step, metrics)
 
     def _maybe_log_save_evaluate(self, tr_loss, model, trial, epoch):
@@ -1593,13 +1603,9 @@ class Trainer:
         )
 
         if self.args.deepspeed and not self.args.do_train:
-            # In the future we probably can run deepspeed for inference too, but this will require
-            # some thinking about how to best run it - since while it works DeepSpeed wasn't
-            # designed for inference
-
-            # since we have to postpone model.to() till training for DeepSpeed, if there was no
-            # training, we must put the model on the right device
-            self.model = self.model.to(self.args.device)
+            # no harm, but flagging to the user that deepspeed config is ignored for eval
+            # flagging only for when --do_train wasn't passed as only then it's redundant
+            logger.info("Detected the deepspeed argument but it will not be used for evaluation")
 
         model = self.model