From 43fa9f22bd0ccf533f975886378ec0c288be0fa1 Mon Sep 17 00:00:00 2001
From: Mick <mickjagger19@icloud.com>
Date: Mon, 29 Sep 2025 11:11:33 +0800
Subject: [PATCH] fix: check if weights are already local before downloading
 (#11015)

---
 .../sglang/srt/model_loader/weight_utils.py   | 97 ++++++++++++++++++-
 1 file changed, 95 insertions(+), 2 deletions(-)

diff --git a/python/sglang/srt/model_loader/weight_utils.py b/python/sglang/srt/model_loader/weight_utils.py
index 397d9e913..0e7089bfc 100644
--- a/python/sglang/srt/model_loader/weight_utils.py
+++ b/python/sglang/srt/model_loader/weight_utils.py
@@ -8,7 +8,6 @@ import hashlib
 import json
 import logging
 import os
-import queue
 import tempfile
 from collections import defaultdict
 from typing import (
@@ -38,7 +37,8 @@ from sglang.srt.distributed import get_tensor_model_parallel_rank
 from sglang.srt.layers.dp_attention import get_attention_tp_rank
 from sglang.srt.layers.quantization import QuantizationConfig, get_quantization_config
 from sglang.srt.layers.quantization.modelopt_quant import ModelOptFp4Config
-from sglang.srt.utils import print_warning_once
+from sglang.srt.utils import find_local_repo_dir, print_warning_once
+from sglang.utils import is_in_ci
 
 logger = logging.getLogger(__name__)
 
@@ -236,6 +236,92 @@ def get_quant_config(
     return quant_cls.from_config(config)
 
 
+def find_local_hf_snapshot_dir(
+    model_name_or_path: str,
+    cache_dir: Optional[str],
+    allow_patterns: List[str],
+    revision: Optional[str] = None,
+) -> Optional[str]:
+    """If the weights are already local, skip downloading and returns the path
+
+    Only applied in ci
+    """
+    if not is_in_ci() or os.path.isdir(model_name_or_path):
+        return None
+
+    found_local_snapshot_dir = None
+
+    # Check custom cache_dir (if provided)
+    if cache_dir:
+        try:
+            repo_folder = os.path.join(
+                cache_dir,
+                huggingface_hub.constants.REPO_ID_SEPARATOR.join(
+                    ["models", *model_name_or_path.split("/")]
+                ),
+            )
+            rev_to_use = revision
+            if not rev_to_use:
+                ref_main = os.path.join(repo_folder, "refs", "main")
+                if os.path.isfile(ref_main):
+                    with open(ref_main) as f:
+                        rev_to_use = f.read().strip()
+            if rev_to_use:
+                rev_dir = os.path.join(repo_folder, "snapshots", rev_to_use)
+                if os.path.isdir(rev_dir):
+                    found_local_snapshot_dir = rev_dir
+        except Exception as e:
+            logger.warning(
+                "Failed to find local snapshot in custom cache_dir %s: %s",
+                cache_dir,
+                e,
+            )
+
+    # Check default HF cache as well
+    if not found_local_snapshot_dir:
+        try:
+            rev_dir = find_local_repo_dir(model_name_or_path, revision)
+            if rev_dir and os.path.isdir(rev_dir):
+                found_local_snapshot_dir = rev_dir
+        except Exception as e:
+            logger.warning("Failed to find local snapshot in default HF cache: %s", e)
+
+    # If local snapshot exists, validate it contains at least one weight file
+    # matching allow_patterns before skipping download.
+    if found_local_snapshot_dir is None:
+        return None
+
+    local_weight_files: List[str] = []
+    try:
+        for pattern in allow_patterns:
+            local_weight_files.extend(
+                glob.glob(os.path.join(found_local_snapshot_dir, pattern))
+            )
+    except Exception as e:
+        logger.warning(
+            "Failed to scan local snapshot %s with patterns %s: %s",
+            found_local_snapshot_dir,
+            allow_patterns,
+            e,
+        )
+        local_weight_files = []
+
+    if len(local_weight_files) > 0:
+        logger.info(
+            "Found local HF snapshot for %s at %s; skipping download.",
+            model_name_or_path,
+            found_local_snapshot_dir,
+        )
+        return found_local_snapshot_dir
+    else:
+        logger.info(
+            "Local HF snapshot at %s has no files matching %s; will attempt download.",
+            found_local_snapshot_dir,
+            allow_patterns,
+        )
+    return None
+
+
 def download_weights_from_hf(
     model_name_or_path: str,
     cache_dir: Optional[str],
@@ -260,6 +346,13 @@ def download_weights_from_hf(
     Returns:
         str: The path to the downloaded model weights.
     """
+
+    path = find_local_hf_snapshot_dir(
+        model_name_or_path, cache_dir, allow_patterns, revision
+    )
+    if path is not None:
+        return path
+
     if not huggingface_hub.constants.HF_HUB_OFFLINE:
         # Before we download we look at that is available:
         fs = HfFileSystem()