use cached_property instead

src/axolotl/utils/models.py

@@ -2,10 +2,12 @@
 
 # pylint: disable=too-many-lines
 import gc
+import importlib
 import logging
 import math
 import os
 import types
+from functools import cached_property
 from typing import Any, Dict, Optional, Tuple, Union  # noqa: F401
 
 import addict
@@ -409,7 +411,7 @@ def apply_patches(self) -> None:
             )
 
             if self.cfg.is_llama_derived_model:
-                self.patch_loss()
+                self.patch_loss_llama()
                 if self.cfg.unsloth_lora_qkv or self.cfg.unsloth_lora_o:
                     from axolotl.monkeypatch.unsloth_ import patch_self_attn_lora
 
@@ -451,27 +453,34 @@ def patch_attention(self) -> None:
 
                 replace_stablelm_attn_with_flash_attn(self.cfg.base_model)
 
-    def patch_loss(self) -> None:
+    @cached_property
+    def flash_attn(self) -> bool:
+        """Check if flash attention is installed"""
+        return importlib.util.find_spec("flash_attn") is not None
+
+    def patch_loss_llama(self) -> None:
         """
         Patch loss functions
         """
-        from axolotl.monkeypatch.llama_attn_hijack_flash import (
-            patch_llama_cross_entropy,
-            patch_llama_rms_norm,
-        )
+        if self.flash_attn:
+            from axolotl.monkeypatch.llama_attn_hijack_flash import (
+                patch_llama_cross_entropy,
+                patch_llama_rms_norm,
+            )
 
-        if self.cfg.flash_attn_cross_entropy:
+        if self.cfg.flash_attn_cross_entropy and self.flash_attn:
             patch_llama_cross_entropy()
-        if self.cfg.flash_attn_rms_norm:
+        elif self.cfg.unsloth_cross_entropy_loss:
+            from axolotl.monkeypatch.unsloth_ import integrate_cross_entropy_loss_patch
+
+            integrate_cross_entropy_loss_patch(model_type="llama")
+
+        if self.cfg.flash_attn_rms_norm and self.flash_attn:
             patch_llama_rms_norm()
         elif self.cfg.unsloth_rms_norm:
             from axolotl.monkeypatch.unsloth_ import patch_unsloth_layernorm
 
             patch_unsloth_layernorm()
-        if self.cfg.unsloth_cross_entropy_loss:
-            from axolotl.monkeypatch.unsloth_ import integrate_cross_entropy_loss_patch
-
-            integrate_cross_entropy_loss_patch(model_type="llama")
         if self.cfg.unsloth_lora_qkv or self.cfg.unsloth_lora_o:
             from axolotl.monkeypatch.unsloth_ import patch_self_attn_lora
 
@@ -481,6 +490,7 @@ def patch_llama_derived_model(self) -> None:
         """
         Modify all llama derived models in one block
         """
+        self.patch_loss_llama()
 
         if self.cfg.flash_attention:
             from axolotl.monkeypatch.llama_attn_hijack_flash import (
@@ -528,16 +538,6 @@ def patch_llama_derived_model(self) -> None:
                 "Shifted-sparse attention not currently implemented without flash attention."
             )
 
-        if self.cfg.unsloth_cross_entropy_loss:
-            from axolotl.monkeypatch.unsloth_ import integrate_cross_entropy_loss_patch
-
-            integrate_cross_entropy_loss_patch(model_type="llama")
-
-        if self.cfg.unsloth_lora_qkv or self.cfg.unsloth_lora_o:
-            from axolotl.monkeypatch.unsloth_ import patch_self_attn_lora
-
-            patch_self_attn_lora()
-
     def set_auto_model_loader(self) -> None:
         """set self.AutoModelLoader
         - default value: AutoModelForCausalLM (set at __init__)