fix: prevent timeout in file encoding detection for large files (#21453)

Co-authored-by: crazywoola <427733928@qq.com>

api/core/rag/extractor/helpers.py

@@ -1,7 +1,6 @@
 """Document loader helpers."""
 
 import concurrent.futures
-from pathlib import Path
 from typing import NamedTuple, Optional, cast
 
 
@@ -16,7 +15,7 @@ class FileEncoding(NamedTuple):
     """The language of the file."""
 
 
-def detect_file_encodings(file_path: str, timeout: int = 5) -> list[FileEncoding]:
+def detect_file_encodings(file_path: str, timeout: int = 5, sample_size: int = 1024 * 1024) -> list[FileEncoding]:
     """Try to detect the file encoding.
 
     Returns a list of `FileEncoding` tuples with the detected encodings ordered
@@ -25,11 +24,16 @@ def detect_file_encodings(file_path: str, timeout: int = 5) -> list[FileEncoding
     Args:
         file_path: The path to the file to detect the encoding for.
         timeout: The timeout in seconds for the encoding detection.
+        sample_size: The number of bytes to read for encoding detection. Default is 1MB.
+                    For large files, reading only a sample is sufficient and prevents timeout.
     """
     import chardet
 
     def read_and_detect(file_path: str) -> list[dict]:
-        rawdata = Path(file_path).read_bytes()
+        with open(file_path, "rb") as f:
+            # Read only a sample of the file for encoding detection
+            # This prevents timeout on large files while still providing accurate encoding detection
+            rawdata = f.read(sample_size)
         return cast(list[dict], chardet.detect_all(rawdata))
 
     with concurrent.futures.ThreadPoolExecutor() as executor: