Modified save_checkpoint to always save last checkpoint. Fixes #98.

timm/utils.py

@@ -62,6 +62,12 @@ class CheckpointSaver:
 
     def save_checkpoint(self, model, optimizer, args, epoch, model_ema=None, metric=None, use_amp=False):
         assert epoch >= 0
+        tmp_save_path = os.path.join(self.checkpoint_dir, 'tmp' + self.extension)
+        last_save_path = os.path.join(self.checkpoint_dir, 'last' + self.extension)
+        self._save(tmp_save_path, model, optimizer, args, epoch, model_ema, metric, use_amp)
+        if os.path.exists(last_save_path):
+            os.unlink(last_save_path) # required for Windows support.
+        os.rename(tmp_save_path, last_save_path)
         worst_file = self.checkpoint_files[-1] if self.checkpoint_files else None
         if (len(self.checkpoint_files) < self.max_history
                 or metric is None or self.cmp(metric, worst_file[1])):
@@ -69,7 +75,7 @@ class CheckpointSaver:
                 self._cleanup_checkpoints(1)
             filename = '-'.join([self.save_prefix, str(epoch)]) + self.extension
             save_path = os.path.join(self.checkpoint_dir, filename)
-            self._save(save_path, model, optimizer, args, epoch, model_ema, metric, use_amp)
+            os.link(last_save_path, save_path)
             self.checkpoint_files.append((save_path, metric))
             self.checkpoint_files = sorted(
                 self.checkpoint_files, key=lambda x: x[1],
@@ -83,7 +89,10 @@ class CheckpointSaver:
             if metric is not None and (self.best_metric is None or self.cmp(metric, self.best_metric)):
                 self.best_epoch = epoch
                 self.best_metric = metric
-                shutil.copyfile(save_path, os.path.join(self.checkpoint_dir, 'model_best' + self.extension))
+                best_save_path = os.path.join(self.checkpoint_dir, 'model_best' + self.extension)
+                if os.path.exists(best_save_path):
+                    os.unlink(best_save_path)
+                os.link(last_save_path, best_save_path)
 
         return (None, None) if self.best_metric is None else (self.best_metric, self.best_epoch)