Harrison/multithreading directory loader (#4650)

Co-authored-by: PawelFaron <42373772+PawelFaron@users.noreply.github.com>
Co-authored-by: Pawel Faron <ext-pawel.faron@vaisala.com>

docs/modules/indexes/document_loaders/examples/file_directory.ipynb

@@ -112,6 +112,34 @@
     "docs = loader.load()"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "c16ed46a",
+   "metadata": {},
+   "source": [
+    "## Use multithreading"
+   ]
+  },
+  {
+   "attachments": {},
+   "cell_type": "markdown",
+   "id": "5752e23e",
+   "metadata": {},
+   "source": [
+    "By default the loading happens in one thread. In order to utilize several threads set the `use_multithreading` flag to true."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "f8d84f52",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "loader = DirectoryLoader('../', glob=\"**/*.md\", use_multithreading=True)\n",
+    "docs = loader.load()"
+   ]
+  },
   {
    "cell_type": "markdown",
    "id": "c5652850",

langchain/document_loaders/directory.py

@@ -1,7 +1,8 @@
 """Loading logic for loading documents from a directory."""
+import concurrent
 import logging
 from pathlib import Path
-from typing import List, Type, Union
+from typing import Any, List, Optional, Type, Union
 
 from langchain.docstore.document import Document
 from langchain.document_loaders.base import BaseLoader
@@ -36,6 +37,8 @@ class DirectoryLoader(BaseLoader):
         loader_kwargs: Union[dict, None] = None,
         recursive: bool = False,
         show_progress: bool = False,
+        use_multithreading: bool = False,
+        max_concurrency: int = 4,
     ):
         """Initialize with path to directory and how to glob over it."""
         if loader_kwargs is None:
@@ -48,11 +51,30 @@ class DirectoryLoader(BaseLoader):
         self.silent_errors = silent_errors
         self.recursive = recursive
         self.show_progress = show_progress
+        self.use_multithreading = use_multithreading
+        self.max_concurrency = max_concurrency
+
+    def load_file(
+        self, item: Path, path: Path, docs: List[Document], pbar: Optional[Any]
+    ) -> None:
+        if item.is_file():
+            if _is_visible(item.relative_to(path)) or self.load_hidden:
+                try:
+                    sub_docs = self.loader_cls(str(item), **self.loader_kwargs).load()
+                    docs.extend(sub_docs)
+                except Exception as e:
+                    if self.silent_errors:
+                        logger.warning(e)
+                    else:
+                        raise e
+                finally:
+                    if pbar:
+                        pbar.update(1)
 
     def load(self) -> List[Document]:
         """Load documents."""
         p = Path(self.path)
-        docs = []
+        docs: List[Document] = []
         items = list(p.rglob(self.glob) if self.recursive else p.glob(self.glob))
 
         pbar = None
@@ -71,22 +93,19 @@ class DirectoryLoader(BaseLoader):
                 else:
                     raise e
 
-        for i in items:
-            if i.is_file():
-                if _is_visible(i.relative_to(p)) or self.load_hidden:
-                    try:
-                        sub_docs = self.loader_cls(str(i), **self.loader_kwargs).load()
-                        docs.extend(sub_docs)
-                    except Exception as e:
-                        if self.silent_errors:
-                            logger.warning(e)
-                        else:
-                            raise e
-                    finally:
-                        if pbar:
-                            pbar.update(1)
+        if self.use_multithreading:
+            with concurrent.futures.ThreadPoolExecutor(
+                max_workers=self.max_concurrency
+            ) as executor:
+                executor.map(lambda i: self.load_file(i, p, docs, pbar), items)
+        else:
+            for i in items:
+                self.load_file(i, p, docs, pbar)
 
         if pbar:
             pbar.close()
 
         return docs
+
+
+#