upgrade xgrammar to 0.1.19 (sgl-project#6129)

Author: Ubospica

python/pyproject.toml

@@ -42,7 +42,7 @@ runtime_common = [
     "transformers==4.51.1",
     "uvicorn",
     "uvloop",
-    "xgrammar==0.1.17",
+    "xgrammar==0.1.19",
     "blobfile==3.0.0"
 ]
 

python/sglang/srt/constrained/xgrammar_backend.py

@@ -18,6 +18,7 @@
 from typing import List, Optional, Tuple, Union
 
 import torch
+import xgrammar
 from xgrammar import (
     CompiledGrammar,
     GrammarCompiler,
@@ -58,17 +59,11 @@ def __init__(
         self.override_stop_tokens = override_stop_tokens
         self.finished = False
 
-        # Fix (from vLLM team): postpone the import of apply_token_bitmask_inplace_kernels to the
-        # class init site to avoid re-initializing CUDA in forked subprocess.
-        from xgrammar.kernels import apply_token_bitmask_inplace_kernels
-
-        self.use_token_bitmask_triton = get_bool_env_var(
-            "SGLANG_TOKEN_BITMASK_TRITON", "false"
-        )
-        self.apply_vocab_mask_cuda = apply_token_bitmask_inplace_kernels.get(
-            "cuda", None
+        from xgrammar.kernels.apply_token_bitmask_inplace_cpu import (
+            apply_token_bitmask_inplace_cpu,
         )
-        self.apply_vocab_mask_cpu = apply_token_bitmask_inplace_kernels.get("cpu", None)
+
+        self.apply_vocab_mask_cpu = apply_token_bitmask_inplace_cpu
 
     def accept_token(self, token: int):
         assert self.matcher.accept_token(token)
@@ -113,15 +108,12 @@ def move_vocab_mask(vocab_mask: torch.Tensor, device) -> torch.Tensor:
         return vocab_mask.to(device, non_blocking=True)
 
     def apply_vocab_mask(self, logits: torch.Tensor, vocab_mask: torch.Tensor) -> None:
-        if (
-            not self.use_token_bitmask_triton
-            and logits.device.type == "cuda"
-            and self.apply_vocab_mask_cuda
-        ):
-            return self.apply_vocab_mask_cuda(logits, vocab_mask)
-        if logits.device.type == "cpu" and self.apply_vocab_mask_cpu:
-            return self.apply_vocab_mask_cpu(logits, vocab_mask)
-        apply_token_bitmask_inplace_triton(logits, vocab_mask)
+        if logits.device.type == "cuda":
+            apply_token_bitmask_inplace_triton(logits, vocab_mask)
+        elif logits.device.type == "cpu" and self.apply_vocab_mask_cpu:
+            self.apply_vocab_mask_cpu(logits, vocab_mask)
+        else:
+            raise RuntimeError(f"Unsupported device: {logits.device.type}")
 
     def copy(self):
         matcher = GrammarMatcher(