Automatic safetensors conversion when lacking these files (#29390)

* Automatic safetensors conversion when lacking these files

* Remove debug

* Thread name

* Typo

* Ensure that raises do not affect the main thread

src/transformers/modeling_utils.py

@@ -29,6 +29,7 @@
 from contextlib import contextmanager
 from dataclasses import dataclass
 from functools import partial, wraps
+from threading import Thread
 from typing import Any, Callable, Dict, List, Optional, Tuple, Union
 from zipfile import is_zipfile
 
@@ -3207,9 +3208,39 @@ def from_pretrained(
                         )
                         if resolved_archive_file is not None:
                             is_sharded = True
-                    if resolved_archive_file is None:
-                        # Otherwise, maybe there is a TF or Flax model file.  We try those to give a helpful error
-                        # message.
+
+                    if resolved_archive_file is not None:
+                        if filename in [WEIGHTS_NAME, WEIGHTS_INDEX_NAME]:
+                            # If the PyTorch file was found, check if there is a safetensors file on the repository
+                            # If there is no safetensors file on the repositories, start an auto conversion
+                            safe_weights_name = SAFE_WEIGHTS_INDEX_NAME if is_sharded else SAFE_WEIGHTS_NAME
+                            has_file_kwargs = {
+                                "revision": revision,
+                                "proxies": proxies,
+                                "token": token,
+                            }
+                            cached_file_kwargs = {
+                                "cache_dir": cache_dir,
+                                "force_download": force_download,
+                                "resume_download": resume_download,
+                                "local_files_only": local_files_only,
+                                "user_agent": user_agent,
+                                "subfolder": subfolder,
+                                "_raise_exceptions_for_gated_repo": False,
+                                "_raise_exceptions_for_missing_entries": False,
+                                "_commit_hash": commit_hash,
+                                **has_file_kwargs,
+                            }
+                            if not has_file(pretrained_model_name_or_path, safe_weights_name, **has_file_kwargs):
+                                Thread(
+                                    target=auto_conversion,
+                                    args=(pretrained_model_name_or_path,),
+                                    kwargs=cached_file_kwargs,
+                                    name="Thread-autoconversion",
+                                ).start()
+                    else:
+                        # Otherwise, no PyTorch file was found, maybe there is a TF or Flax model file.
+                        # We try those to give a helpful error message.
                         has_file_kwargs = {
                             "revision": revision,
                             "proxies": proxies,

tests/test_modeling_utils.py

@@ -20,6 +20,7 @@
 import os.path
 import sys
 import tempfile
+import threading
 import unittest
 import unittest.mock as mock
 import uuid
@@ -1428,7 +1429,7 @@ def test_safetensors_on_the_fly_wrong_user_opened_pr(self):
             bot_opened_pr_title = None
 
             for discussion in discussions:
-                if discussion.author == "SFconvertBot":
+                if discussion.author == "SFconvertbot":
                     bot_opened_pr = True
                     bot_opened_pr_title = discussion.title
 
@@ -1451,6 +1452,51 @@ def test_safetensors_on_the_fly_specific_revision(self):
         with self.assertRaises(EnvironmentError):
             BertModel.from_pretrained(self.repo_name, use_safetensors=True, token=self.token, revision="new-branch")
 
+    def test_absence_of_safetensors_triggers_conversion(self):
+        config = BertConfig(
+            vocab_size=99, hidden_size=32, num_hidden_layers=5, num_attention_heads=4, intermediate_size=37
+        )
+        initial_model = BertModel(config)
+
+        # Push a model on `main`
+        initial_model.push_to_hub(self.repo_name, token=self.token, safe_serialization=False)
+
+        # Download the model that doesn't have safetensors
+        BertModel.from_pretrained(self.repo_name, token=self.token)
+
+        for thread in threading.enumerate():
+            if thread.name == "Thread-autoconversion":
+                thread.join(timeout=10)
+
+        with self.subTest("PR was open with the safetensors account"):
+            discussions = self.api.get_repo_discussions(self.repo_name)
+
+            bot_opened_pr = None
+            bot_opened_pr_title = None
+
+            for discussion in discussions:
+                if discussion.author == "SFconvertbot":
+                    bot_opened_pr = True
+                    bot_opened_pr_title = discussion.title
+
+            self.assertTrue(bot_opened_pr)
+            self.assertEqual(bot_opened_pr_title, "Adding `safetensors` variant of this model")
+
+    @mock.patch("transformers.safetensors_conversion.spawn_conversion")
+    def test_absence_of_safetensors_triggers_conversion_failed(self, spawn_conversion_mock):
+        spawn_conversion_mock.side_effect = HTTPError()
+
+        config = BertConfig(
+            vocab_size=99, hidden_size=32, num_hidden_layers=5, num_attention_heads=4, intermediate_size=37
+        )
+        initial_model = BertModel(config)
+
+        # Push a model on `main`
+        initial_model.push_to_hub(self.repo_name, token=self.token, safe_serialization=False)
+
+        # The auto conversion is mocked to always raise; ensure that it doesn't raise in the main thread
+        BertModel.from_pretrained(self.repo_name, token=self.token)
+
 
 @require_torch
 @is_staging_test