diff --git a/.pylintrc b/.pylintrc
index 45c2b04b..094d8888 100644
--- a/.pylintrc
+++ b/.pylintrc
@@ -452,6 +452,7 @@ disable=raw-checker-failed,
         R0917,  # Too many positional arguments (6/5) (too-many-positional-arguments)
         C0103,
         E0401,
+        W0718, # Catching too general exception Exception (broad-except)
 
 # Enable the message, report, category or checker with the given id(s). You can
 # either give multiple identifier separated by comma (,) or put this option
diff --git a/graphgen/graphgen.py b/graphgen/graphgen.py
index 6df22cb0..31a8b94a 100644
--- a/graphgen/graphgen.py
+++ b/graphgen/graphgen.py
@@ -67,15 +67,16 @@ def __init__(
         self.graph_storage: NetworkXStorage = NetworkXStorage(
             self.working_dir, namespace="graph"
         )
-        self.search_storage: JsonKVStorage = JsonKVStorage(
-            self.working_dir, namespace="search"
-        )
         self.rephrase_storage: JsonKVStorage = JsonKVStorage(
             self.working_dir, namespace="rephrase"
         )
         self.partition_storage: JsonListStorage = JsonListStorage(
             self.working_dir, namespace="partition"
         )
+        self.search_storage: JsonKVStorage = JsonKVStorage(
+            os.path.join(self.working_dir, "data", "graphgen", f"{self.unique_id}"),
+            namespace="search",
+        )
         self.qa_storage: JsonListStorage = JsonListStorage(
             os.path.join(self.working_dir, "data", "graphgen", f"{self.unique_id}"),
             namespace="qa",
@@ -94,23 +95,24 @@ async def read(self, read_config: Dict):
         """
         read files from input sources
         """
-        data = read_files(**read_config, cache_dir=self.working_dir)
-        if len(data) == 0:
-            logger.warning("No data to process")
-            return
+        doc_stream = read_files(**read_config, cache_dir=self.working_dir)
 
-        assert isinstance(data, list) and isinstance(data[0], dict)
+        batch = {}
+        for doc in doc_stream:
+            doc_id = compute_mm_hash(doc, prefix="doc-")
 
-        # TODO: configurable whether to use coreference resolution
+            batch[doc_id] = doc
+        if batch:
+            self.full_docs_storage.upsert(batch)
+            self.full_docs_storage.index_done_callback()
 
-        new_docs = {compute_mm_hash(doc, prefix="doc-"): doc for doc in data}
-        _add_doc_keys = self.full_docs_storage.filter_keys(list(new_docs.keys()))
-        new_docs = {k: v for k, v in new_docs.items() if k in _add_doc_keys}
+        # TODO: configurable whether to use coreference resolution
 
+        _add_doc_keys = self.full_docs_storage.filter_keys(list(batch.keys()))
+        new_docs = {k: v for k, v in batch.items() if k in _add_doc_keys}
         if len(new_docs) == 0:
             logger.warning("All documents are already in the storage")
             return
-
         self.full_docs_storage.upsert(new_docs)
         self.full_docs_storage.index_done_callback()
 
diff --git a/graphgen/operators/read/parallel_file_scanner.py b/graphgen/operators/read/parallel_file_scanner.py
new file mode 100644
index 00000000..890a50a9
--- /dev/null
+++ b/graphgen/operators/read/parallel_file_scanner.py
@@ -0,0 +1,231 @@
+import os
+import time
+from concurrent.futures import ThreadPoolExecutor, as_completed
+from pathlib import Path
+from typing import Any, Dict, List, Set, Union
+
+from diskcache import Cache
+
+from graphgen.utils import logger
+
+
+class ParallelFileScanner:
+    def __init__(
+        self, cache_dir: str, allowed_suffix, rescan: bool = False, max_workers: int = 4
+    ):
+        self.cache = Cache(cache_dir)
+        self.allowed_suffix = set(allowed_suffix) if allowed_suffix else None
+        self.rescan = rescan
+        self.max_workers = max_workers
+
+    def scan(
+        self, paths: Union[str, List[str]], recursive: bool = True
+    ) -> Dict[str, Any]:
+        if isinstance(paths, str):
+            paths = [paths]
+
+        results = {}
+        with ThreadPoolExecutor(max_workers=self.max_workers) as executor:
+            future_to_path = {}
+            for p in paths:
+                if os.path.exists(p):
+                    future = executor.submit(
+                        self._scan_files, Path(p).resolve(), recursive, set()
+                    )
+                    future_to_path[future] = p
+                else:
+                    logger.warning("[READ] Path does not exist: %s", p)
+
+            for future in as_completed(future_to_path):
+                path = future_to_path[future]
+                try:
+                    results[path] = future.result()
+                except Exception as e:
+                    logger.error("[READ] Error scanning path %s: %s", path, e)
+                    results[path] = {
+                        "error": str(e),
+                        "files": [],
+                        "dirs": [],
+                        "stats": {},
+                    }
+        return results
+
+    def _scan_files(
+        self, path: Path, recursive: bool, visited: Set[str]
+    ) -> Dict[str, Any]:
+        path_str = str(path)
+
+        # Avoid cycles due to symlinks
+        if path_str in visited:
+            logger.warning("[READ] Skipping already visited path: %s", path_str)
+            return self._empty_result(path_str)
+
+        # cache check
+        cache_key = f"scan::{path_str}::recursive::{recursive}"
+        cached = self.cache.get(cache_key)
+        if cached and not self.rescan:
+            logger.info("[READ] Using cached scan result for path: %s", path_str)
+            return cached["data"]
+
+        logger.info("[READ] Scanning path: %s", path_str)
+        files, dirs = [], []
+        stats = {"total_size": 0, "file_count": 0, "dir_count": 0, "errors": 0}
+
+        try:
+            path_stat = path.stat()
+            if path.is_file():
+                return self._scan_single_file(path, path_str, path_stat)
+            if path.is_dir():
+                with os.scandir(path_str) as entries:
+                    for entry in entries:
+                        try:
+                            entry_stat = entry.stat(follow_symlinks=False)
+
+                            if entry.is_dir():
+                                dirs.append(
+                                    {
+                                        "path": entry.path,
+                                        "name": entry.name,
+                                        "mtime": entry_stat.st_mtime,
+                                    }
+                                )
+                                stats["dir_count"] += 1
+                            else:
+                                # allowed suffix filter
+                                if not self._is_allowed_file(Path(entry.path)):
+                                    continue
+                                files.append(
+                                    {
+                                        "path": entry.path,
+                                        "name": entry.name,
+                                        "size": entry_stat.st_size,
+                                        "mtime": entry_stat.st_mtime,
+                                    }
+                                )
+                                stats["total_size"] += entry_stat.st_size
+                                stats["file_count"] += 1
+
+                        except OSError:
+                            stats["errors"] += 1
+
+        except (PermissionError, FileNotFoundError, OSError) as e:
+            logger.error("[READ] Failed to scan path %s: %s", path_str, e)
+            return {"error": str(e), "files": [], "dirs": [], "stats": stats}
+
+        if recursive:
+            sub_visited = visited | {path_str}
+            sub_results = self._scan_subdirs(dirs, sub_visited)
+
+            for sub_data in sub_results.values():
+                files.extend(sub_data.get("files", []))
+                stats["total_size"] += sub_data["stats"].get("total_size", 0)
+                stats["file_count"] += sub_data["stats"].get("file_count", 0)
+
+        result = {"path": path_str, "files": files, "dirs": dirs, "stats": stats}
+        self._cache_result(cache_key, result, path)
+        return result
+
+    def _scan_single_file(
+        self, path: Path, path_str: str, stat: os.stat_result
+    ) -> Dict[str, Any]:
+        """Scan a single file and return its metadata"""
+        if not self._is_allowed_file(path):
+            return self._empty_result(path_str)
+
+        return {
+            "path": path_str,
+            "files": [
+                {
+                    "path": path_str,
+                    "name": path.name,
+                    "size": stat.st_size,
+                    "mtime": stat.st_mtime,
+                }
+            ],
+            "dirs": [],
+            "stats": {
+                "total_size": stat.st_size,
+                "file_count": 1,
+                "dir_count": 0,
+                "errors": 0,
+            },
+        }
+
+    def _scan_subdirs(self, dir_list: List[Dict], visited: Set[str]) -> Dict[str, Any]:
+        """
+        Parallel scan subdirectories
+        :param dir_list
+        :param visited
+        :return:
+        """
+        results = {}
+        with ThreadPoolExecutor(max_workers=self.max_workers) as executor:
+            futures = {
+                executor.submit(self._scan_files, Path(d["path"]), True, visited): d[
+                    "path"
+                ]
+                for d in dir_list
+            }
+
+            for future in as_completed(futures):
+                path = futures[future]
+                try:
+                    results[path] = future.result()
+                except Exception as e:
+                    logger.error("[READ] Error scanning subdirectory %s: %s", path, e)
+                    results[path] = {
+                        "error": str(e),
+                        "files": [],
+                        "dirs": [],
+                        "stats": {},
+                    }
+
+        return results
+
+    def _cache_result(self, key: str, result: Dict, path: Path):
+        """Cache the scan result"""
+        try:
+            self.cache.set(
+                key,
+                {
+                    "data": result,
+                    "dir_mtime": path.stat().st_mtime,
+                    "cached_at": time.time(),
+                },
+            )
+            logger.info("[READ] Cached scan result for path: %s", path)
+        except OSError as e:
+            logger.error("[READ] Failed to cache scan result for path %s: %s", path, e)
+
+    def _is_allowed_file(self, path: Path) -> bool:
+        """Check if the file has an allowed suffix"""
+        if self.allowed_suffix is None:
+            return True
+        suffix = path.suffix.lower().lstrip(".")
+        return suffix in self.allowed_suffix
+
+    def invalidate(self, path: str):
+        """Invalidate cache for a specific path"""
+        path = Path(path).resolve()
+        keys = [k for k in self.cache if k.startswith(f"scan::{path}")]
+        for k in keys:
+            self.cache.delete(k)
+        logger.info("[READ] Invalidated cache for path: %s", path)
+
+    def close(self):
+        self.cache.close()
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *args):
+        self.close()
+
+    @staticmethod
+    def _empty_result(path: str) -> Dict[str, Any]:
+        return {
+            "path": path,
+            "files": [],
+            "dirs": [],
+            "stats": {"total_size": 0, "file_count": 0, "dir_count": 0, "errors": 0},
+        }
diff --git a/graphgen/operators/read/read_files.py b/graphgen/operators/read/read_files.py
index b940b439..d9e7f673 100644
--- a/graphgen/operators/read/read_files.py
+++ b/graphgen/operators/read/read_files.py
@@ -1,5 +1,5 @@
 from pathlib import Path
-from typing import Any, Dict, List, Optional
+from typing import Any, Dict, Iterator, List, Optional
 
 from graphgen.models import (
     CSVReader,
@@ -13,6 +13,8 @@
 )
 from graphgen.utils import logger
 
+from .parallel_file_scanner import ParallelFileScanner
+
 _MAPPING = {
     "jsonl": JSONLReader,
     "json": JSONReader,
@@ -39,7 +41,20 @@ def read_files(
     input_file: str,
     allowed_suffix: Optional[List[str]] = None,
     cache_dir: Optional[str] = None,
-) -> list[dict]:
+    max_workers: int = 4,
+    rescan: bool = False,
+) -> Iterator[Dict[str, Any]]:
+    """
+    Read files from a path using parallel scanning and appropriate readers.
+
+    Args:
+        input_file: Path to a file or directory
+        allowed_suffix: List of file suffixes to read. If None, uses all supported types
+        cache_dir: Directory for caching PDF extraction and scan results
+        max_workers: Number of workers for parallel scanning
+        rescan: Whether to force rescan even if cached results exist
+    """
+
     path = Path(input_file).expanduser()
     if not path.exists():
         raise FileNotFoundError(f"input_path not found: {input_file}")
@@ -49,24 +64,22 @@ def read_files(
     else:
         support_suffix = {s.lower().lstrip(".") for s in allowed_suffix}
 
-    # single file
-    if path.is_file():
-        suffix = path.suffix.lstrip(".").lower()
-        if suffix not in support_suffix:
-            logger.warning(
-                "Skip file %s (suffix '%s' not in allowed_suffix %s)",
-                path,
-                suffix,
-                support_suffix,
-            )
-            return []
-        reader = _build_reader(suffix, cache_dir)
-        return reader.read(str(path))
-
-    # folder
-    files_to_read = [
-        p for p in path.rglob("*") if p.suffix.lstrip(".").lower() in support_suffix
-    ]
+    with ParallelFileScanner(
+        cache_dir=cache_dir or "cache",
+        allowed_suffix=support_suffix,
+        rescan=rescan,
+        max_workers=max_workers,
+    ) as scanner:
+        scan_results = scanner.scan(str(path), recursive=True)
+
+    # Extract files from scan results
+    files_to_read = []
+    for path_result in scan_results.values():
+        if "error" in path_result:
+            logger.warning("Error scanning %s: %s", path_result.path, path_result.error)
+            continue
+        files_to_read.extend(path_result.get("files", []))
+
     logger.info(
         "Found %d eligible file(s) under folder %s (allowed_suffix=%s)",
         len(files_to_read),
@@ -74,13 +87,13 @@ def read_files(
         support_suffix,
     )
 
-    all_docs: List[Dict[str, Any]] = []
-    for p in files_to_read:
+    for file_info in files_to_read:
         try:
-            suffix = p.suffix.lstrip(".").lower()
+            file_path = file_info["path"]
+            suffix = Path(file_path).suffix.lstrip(".").lower()
             reader = _build_reader(suffix, cache_dir)
-            all_docs.extend(reader.read(str(p)))
-        except Exception as e:  # pylint: disable=broad-except
-            logger.exception("Error reading %s: %s", p, e)
 
-    return all_docs
+            yield from reader.read(file_path)
+
+        except Exception as e:  # pylint: disable=broad-except
+            logger.exception("Error reading %s: %s", file_info.get("path"), e)
diff --git a/requirements.txt b/requirements.txt
index 655165af..47965013 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -20,6 +20,7 @@ requests
 fastapi
 trafilatura
 aiohttp
+diskcache
 
 leidenalg
 igraph