Move mem_fraction_static adjustment for multimodal models to server_args.py & Fix session control & Other cleanups (#7748)

python/sglang/srt/server_args.py

@@ -319,6 +319,14 @@ class ServerArgs:
             else:
                 self.mem_fraction_static = 0.88
 
+            # Lazy init to avoid circular import
+            from sglang.srt.configs.model_config import ModelConfig
+
+            # Multimodal models need more memory for the image processor
+            model_config = ModelConfig.from_server_args(self)
+            if model_config.is_multimodal:
+                self.mem_fraction_static *= 0.90
+
         # Set chunked prefill size, which depends on the gpu memory capacity
         if self.chunked_prefill_size is None:
             if gpu_mem is not None: