Make sure --free_gpu_mem still works when using CKPT-based diffuser model (#2367)

This PR attempts to fix `--free_gpu_mem` option that was not working in
CKPT-based diffuser model after #1583.

I noticed that the memory usage after #1583 did not decrease after
generating an image when `--free_gpu_mem` option was enabled.
It turns out that the option was not propagated into `Generator`
instance, hence the generation will always run without the memory saving
procedure.

This PR also related to #2326. Initially, I was trying to make
`--free_gpu_mem` works on 🤗 diffuser model as well.
In the process, I noticed that InvokeAI will raise an exception when
`--free_gpu_mem` is enabled.
I tried to quickly fix it by simply ignoring the exception and produce a
warning message to user's console.

ldm/generate.py

@@ -146,7 +146,7 @@ class Generate:
             gfpgan=None,
             codeformer=None,
             esrgan=None,
-            free_gpu_mem=False,
+            free_gpu_mem: bool=False,
             safety_checker:bool=False,
             max_loaded_models:int=2,
             # these are deprecated; if present they override values in the conf file
@@ -460,10 +460,13 @@ class Generate:
         init_image = None
         mask_image = None
 
-
-        if self.free_gpu_mem and self.model.cond_stage_model.device != self.model.device:
-            self.model.cond_stage_model.device = self.model.device
-            self.model.cond_stage_model.to(self.model.device)
+        try:
+            if self.free_gpu_mem and self.model.cond_stage_model.device != self.model.device:
+                self.model.cond_stage_model.device = self.model.device
+                self.model.cond_stage_model.to(self.model.device)
+        except AttributeError:
+            print(">> Warning: '--free_gpu_mem' is not yet supported when generating image using model based on HuggingFace Diffuser.")
+            pass
 
         try:
             uc, c, extra_conditioning_info = get_uc_and_c_and_ec(
@@ -531,6 +534,7 @@ class Generate:
                 inpaint_height = inpaint_height,
                 inpaint_width = inpaint_width,
                 enable_image_debugging = enable_image_debugging,
+                free_gpu_mem=self.free_gpu_mem,
             )
 
             if init_color:

ldm/invoke/ckpt_generator/base.py

@@ -56,9 +56,11 @@ class CkptGenerator():
                  image_callback=None, step_callback=None, threshold=0.0, perlin=0.0,
                  safety_checker:dict=None,
                  attention_maps_callback = None,
+                 free_gpu_mem: bool=False,
                  **kwargs):
         scope = choose_autocast(self.precision)
         self.safety_checker = safety_checker
+        self.free_gpu_mem = free_gpu_mem
         attention_maps_images = []
         attention_maps_callback = lambda saver: attention_maps_images.append(saver.get_stacked_maps_image())
         make_image = self.get_make_image(

ldm/invoke/generator/base.py

@@ -62,9 +62,11 @@ class Generator:
     def generate(self,prompt,init_image,width,height,sampler, iterations=1,seed=None,
                  image_callback=None, step_callback=None, threshold=0.0, perlin=0.0,
                  safety_checker:dict=None,
+                 free_gpu_mem: bool=False,
                  **kwargs):
         scope = nullcontext
         self.safety_checker = safety_checker
+        self.free_gpu_mem = free_gpu_mem
         attention_maps_images = []
         attention_maps_callback = lambda saver: attention_maps_images.append(saver.get_stacked_maps_image())
         make_image = self.get_make_image(