From 61aa3293d35a010ab610acf46d401ba03cb5ff22 Mon Sep 17 00:00:00 2001
From: Cheng Wan <54331508+ch-wan@users.noreply.github.com>
Date: Wed, 3 Jun 2026 14:53:28 -0700
Subject: [PATCH] Revert "Fix TokenizerManager crash on top_logprobs with
 tensor values" (#27187)

---
 .../sglang/srt/managers/tokenizer_manager.py  |  2 +-
 ...t_tokenizer_manager_top_logprobs_tensor.py | 82 -------------------
 2 files changed, 1 insertion(+), 83 deletions(-)
 delete mode 100644 test/registered/unit/managers/test_tokenizer_manager_top_logprobs_tensor.py

diff --git a/python/sglang/srt/managers/tokenizer_manager.py b/python/sglang/srt/managers/tokenizer_manager.py
index 4937acd14..2168f053c 100644
--- a/python/sglang/srt/managers/tokenizer_manager.py
+++ b/python/sglang/srt/managers/tokenizer_manager.py
@@ -2188,7 +2188,7 @@ class TokenizerManager(TokenizerControlMixin, TokenizerManagerScoreMixin):
         # We should batch all top-k tokens in all positions.
         ret = []
         for i in range(len(token_logprobs_val)):
-            if token_logprobs_val[i] is not None:
+            if token_logprobs_val[i]:
                 ret.append(
                     self.detokenize_logprob_tokens(
                         token_logprobs_val[i], token_logprobs_idx[i], decode_to_text
diff --git a/test/registered/unit/managers/test_tokenizer_manager_top_logprobs_tensor.py b/test/registered/unit/managers/test_tokenizer_manager_top_logprobs_tensor.py
deleted file mode 100644
index de044b807..000000000
--- a/test/registered/unit/managers/test_tokenizer_manager_top_logprobs_tensor.py
+++ /dev/null
@@ -1,82 +0,0 @@
-"""
-Unit tests for TokenizerManager.detokenize_top_logprobs_tokens.
-
-Regression coverage for a crash where a per-position logprob value is a
-multi-element torch.Tensor instead of the annotated List[float]. The old
-truthiness check ``if token_logprobs_val[i]:`` raises::
-
-    RuntimeError: Boolean value of Tensor with more than one value is ambiguous.
-
-which propagates out of the detokenization handler, gets caught by
-print_exception_wrapper, and SIGKILLs the whole (prefill) process. The fix
-uses an explicit ``is not None`` test that matches the actual sentinel for
-skipped positions and works for both lists and tensors.
-"""
-
-import unittest
-
-import torch
-
-from sglang.test.ci.ci_register import register_cpu_ci
-from sglang.test.test_utils import CustomTestCase, maybe_stub_sgl_kernel
-
-maybe_stub_sgl_kernel()
-
-from sglang.srt.managers.tokenizer_manager import TokenizerManager
-
-register_cpu_ci(est_time=5, suite="base-a-test-cpu")
-
-
-def _make_tokenizer_manager() -> TokenizerManager:
-    """Create a bare TokenizerManager, bypassing __init__.
-
-    detokenize_top_logprobs_tokens / detokenize_logprob_tokens only touch
-    self.tokenizer when decode_to_text=True, so an uninitialised instance is
-    sufficient for the decode_to_text=False paths exercised here.
-    """
-    return TokenizerManager.__new__(TokenizerManager)
-
-
-class TestDetokenizeTopLogprobsTensor(CustomTestCase):
-    def test_multi_element_tensor_value_does_not_crash(self):
-        """A multi-element tensor position must be detokenized, not raise."""
-        tm = _make_tokenizer_manager()
-
-        val = [torch.tensor([-0.1, -0.2, -0.3])]
-        idx = [[10, 20, 30]]
-
-        ret = tm.detokenize_top_logprobs_tokens(val, idx, decode_to_text=False)
-
-        self.assertEqual(len(ret), 1)
-        self.assertEqual(
-            ret[0],
-            [(-0.1, 10, None), (-0.2, 20, None), (-0.3, 30, None)],
-        )
-
-    def test_none_position_yields_none(self):
-        """None is the sentinel for skipped positions and must stay None."""
-        tm = _make_tokenizer_manager()
-
-        val = [None, torch.tensor([-0.5, -0.6])]
-        idx = [None, [1, 2]]
-
-        ret = tm.detokenize_top_logprobs_tokens(val, idx, decode_to_text=False)
-
-        self.assertEqual(len(ret), 2)
-        self.assertIsNone(ret[0])
-        self.assertEqual(ret[1], [(-0.5, 1, None), (-0.6, 2, None)])
-
-    def test_plain_list_values_still_work(self):
-        """The ordinary List[float] path is unaffected by the fix."""
-        tm = _make_tokenizer_manager()
-
-        val = [[-0.1, -0.2]]
-        idx = [[7, 8]]
-
-        ret = tm.detokenize_top_logprobs_tokens(val, idx, decode_to_text=False)
-
-        self.assertEqual(ret, [[(-0.1, 7, None), (-0.2, 8, None)]])
-
-
-if __name__ == "__main__":
-    unittest.main(verbosity=2)