Refa: asyncio.to_thread to ThreadPoolExecutor to break thread limitat… (#12716)

### Type of change

- [x] Refactoring

graphrag/general/graph_extractor.py

@@ -1,11 +1,13 @@
 # Copyright (c) 2024 Microsoft Corporation.
 # Licensed under the MIT License
+
+from common.misc_utils import thread_pool_exec
+
 """
 Reference:
  - [graphrag](https://github.com/microsoft/graphrag)
 """
 
-import asyncio
 import re
 from typing import Any
 from dataclasses import dataclass
@@ -107,7 +109,7 @@ class GraphExtractor(Extractor):
         }
         hint_prompt = perform_variable_replacements(self._extraction_prompt, variables=variables)
         async with chat_limiter:
-            response = await asyncio.to_thread(self._chat,hint_prompt,[{"role": "user", "content": "Output:"}],{},task_id)
+            response = await thread_pool_exec(self._chat,hint_prompt,[{"role": "user", "content": "Output:"}],{},task_id)
         token_count += num_tokens_from_string(hint_prompt + response)
 
         results = response or ""
@@ -117,7 +119,7 @@ class GraphExtractor(Extractor):
         for i in range(self._max_gleanings):
             history.append({"role": "user", "content": CONTINUE_PROMPT})
             async with chat_limiter:
-                response = await asyncio.to_thread(self._chat, "", history, {})
+                response = await thread_pool_exec(self._chat, "", history, {})
             token_count += num_tokens_from_string("\n".join([m["content"] for m in history]) + response)
             results += response or ""
 
@@ -127,7 +129,7 @@ class GraphExtractor(Extractor):
             history.append({"role": "assistant", "content": response})
             history.append({"role": "user", "content": LOOP_PROMPT})
             async with chat_limiter:
-                continuation = await asyncio.to_thread(self._chat, "", history)
+                continuation = await thread_pool_exec(self._chat, "", history)
             token_count += num_tokens_from_string("\n".join([m["content"] for m in history]) + response)
             if continuation != "Y":
                 break