Refa:replace trio with asyncio (#11831)

### What problem does this PR solve?

change:
replace trio with asyncio

### Type of change
- [x] Refactoring

deepdoc/parser/pdf_parser.py

@@ -14,6 +14,7 @@
 #  limitations under the License.
 #
 
+import asyncio
 import logging
 import math
 import os
@@ -28,7 +29,6 @@ from timeit import default_timer as timer
 
 import numpy as np
 import pdfplumber
-import trio
 import xgboost as xgb
 from huggingface_hub import snapshot_download
 from PIL import Image
@@ -65,7 +65,7 @@ class RAGFlowPdfParser:
         self.ocr = OCR()
         self.parallel_limiter = None
         if settings.PARALLEL_DEVICES > 1:
-            self.parallel_limiter = [trio.CapacityLimiter(1) for _ in range(settings.PARALLEL_DEVICES)]
+            self.parallel_limiter = [asyncio.Semaphore(1) for _ in range(settings.PARALLEL_DEVICES)]
 
         layout_recognizer_type = os.getenv("LAYOUT_RECOGNIZER_TYPE", "onnx").lower()
         if layout_recognizer_type not in ["onnx", "ascend"]:
@@ -382,7 +382,7 @@ class RAGFlowPdfParser:
                 else:
                     x0s.append([x])
             x0s = np.array(x0s, dtype=float)
-            
+
             max_try = min(4, len(bxs))
             if max_try < 2:
                 max_try = 1
@@ -416,7 +416,7 @@ class RAGFlowPdfParser:
         for pg, bxs in by_page.items():
             if not bxs:
                 continue
-            k = page_cols[pg] 
+            k = page_cols[pg]
             if len(bxs) < k:
                 k = 1
             x0s = np.array([[b["x0"]] for b in bxs], dtype=float)
@@ -430,7 +430,7 @@ class RAGFlowPdfParser:
 
             for b, lb in zip(bxs, labels):
                 b["col_id"] = remap[lb]
-            
+
             grouped = defaultdict(list)
             for b in bxs:
                 grouped[b["col_id"]].append(b)
@@ -1111,7 +1111,7 @@ class RAGFlowPdfParser:
 
             if limiter:
                 async with limiter:
-                    await trio.to_thread.run_sync(lambda: self.__ocr(i + 1, img, chars, zoomin, id))
+                    await asyncio.to_thread(self.__ocr, i + 1, img, chars, zoomin, id)
             else:
                 self.__ocr(i + 1, img, chars, zoomin, id)
 
@@ -1127,12 +1127,34 @@ class RAGFlowPdfParser:
                 return chars
 
             if self.parallel_limiter:
-                async with trio.open_nursery() as nursery:
-                    for i, img in enumerate(self.page_images):
-                        chars = __ocr_preprocess()
+                tasks = []
+
+                for i, img in enumerate(self.page_images):
+                    chars = __ocr_preprocess()
+
+                    semaphore = self.parallel_limiter[i % settings.PARALLEL_DEVICES]
+
+                    async def wrapper(i=i, img=img, chars=chars, semaphore=semaphore):
+                        await __img_ocr(
+                            i,
+                            i % settings.PARALLEL_DEVICES,
+                            img,
+                            chars,
+                            semaphore,
+                        )
+
+                    tasks.append(asyncio.create_task(wrapper()))
+                    await asyncio.sleep(0)
+
+                try:
+                    await asyncio.gather(*tasks, return_exceptions=False)
+                except Exception as e:
+                    logging.error(f"Error in OCR: {e}")
+                    for t in tasks:
+                        t.cancel()
+                    await asyncio.gather(*tasks, return_exceptions=True)
+                    raise
 
-                        nursery.start_soon(__img_ocr, i, i % settings.PARALLEL_DEVICES, img, chars, self.parallel_limiter[i % settings.PARALLEL_DEVICES])
-                        await trio.sleep(0.1)
             else:
                 for i, img in enumerate(self.page_images):
                     chars = __ocr_preprocess()
@@ -1140,7 +1162,7 @@ class RAGFlowPdfParser:
 
         start = timer()
 
-        trio.run(__img_ocr_launcher)
+        asyncio.run(__img_ocr_launcher())
 
         logging.info(f"__images__ {len(self.page_images)} pages cost {timer() - start}s")