@tduncan / Nvidia-Optimization-Stack-VLLM / commits / b040321b33

fix: perf: use startswith(x, i) instead of string slicing to avoid O(N^2) (#52580)

Signed-off-by: Ricardo-M-L <ricardoporsche001@icloud.com> Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Ricardo-M-L committed Sep 26, 2026 at 07:22 UTC b040321b333c1e9d1b9074d1a8c70e361544667e

1 file changed +6 -6

vllm/parser/gemma4.py

+6 -6

@@ -120,7 +120,7 @@ def _parse_gemma4_args(args_str: str, *, partial: bool = False) -> dict:

120 result[key] = ""

121 break

122

123 - if args_str[i : i + _DELIM_LEN] == STRING_DELIM:

123 + if args_str.startswith(STRING_DELIM, i):

124 i += _DELIM_LEN

125 val_start = i

126 end_pos = args_str.find(STRING_DELIM, i)

@@ -139,7 +139,7 @@ def _parse_gemma4_args(args_str: str, *, partial: bool = False) -> dict:

139 obj_start = i + 1

140 i += 1

141 while i < n and depth > 0:

142 - if args_str[i : i + _DELIM_LEN] == STRING_DELIM:

142 + if args_str.startswith(STRING_DELIM, i):

143 # Skip over string contents to avoid counting { inside strings

144 i += _DELIM_LEN

145 next_delim = args_str.find(STRING_DELIM, i)

@@ -162,7 +162,7 @@ def _parse_gemma4_args(args_str: str, *, partial: bool = False) -> dict:

162 arr_start = i + 1

163 i += 1

164 while i < n and depth > 0:

165 - if args_str[i : i + _DELIM_LEN] == STRING_DELIM:

165 + if args_str.startswith(STRING_DELIM, i):

166 i += _DELIM_LEN

167 next_delim = args_str.find(STRING_DELIM, i)

168 i = n if next_delim == -1 else next_delim + _DELIM_LEN

@@ -213,7 +213,7 @@ def _parse_gemma4_array(arr_str: str, *, partial: bool = False) -> list:

213 if i >= n:

214 break

215

216 - if arr_str[i : i + _DELIM_LEN] == STRING_DELIM:

216 + if arr_str.startswith(STRING_DELIM, i):

217 i += _DELIM_LEN

218 end_pos = arr_str.find(STRING_DELIM, i)

219 if end_pos == -1:

@@ -227,7 +227,7 @@ def _parse_gemma4_array(arr_str: str, *, partial: bool = False) -> list:

227 obj_start = i + 1

228 i += 1

229 while i < n and depth > 0:

230 - if arr_str[i : i + _DELIM_LEN] == STRING_DELIM:

230 + if arr_str.startswith(STRING_DELIM, i):

231 i += _DELIM_LEN

232 nd = arr_str.find(STRING_DELIM, i)

233 i = nd + _DELIM_LEN if nd != -1 else n

@@ -247,7 +247,7 @@ def _parse_gemma4_array(arr_str: str, *, partial: bool = False) -> list:

247 sub_start = i + 1

248 i += 1

249 while i < n and depth > 0:

250 - if arr_str[i : i + _DELIM_LEN] == STRING_DELIM:

250 + if arr_str.startswith(STRING_DELIM, i):

251 i += _DELIM_LEN

252 nd = arr_str.find(STRING_DELIM, i)

253 i = nd + _DELIM_LEN if nd != -1 else n