From d6471f84ce9945647e5e2657e0f4b022430869f9 Mon Sep 17 00:00:00 2001
From: mateo-berri <277851410+mateo-berri@users.noreply.github.com>
Date: Fri, 30 Oct 2026 11:37:16 -0700
Subject: [PATCH] perf(logging): keep main's copy and offload, skip the regex
 for strings without data URI markers

---
 litellm/litellm_core_utils/logging_utils.py     | 12 +++++-------
 .../litellm_core_utils/test_logging_utils.py    | 17 ++++++-----------
 2 files changed, 11 insertions(+), 18 deletions(-)

diff --git a/litellm/litellm_core_utils/logging_utils.py b/litellm/litellm_core_utils/logging_utils.py
index 9a139b2f67d..c7477de8a76 100644
--- a/litellm/litellm_core_utils/logging_utils.py
+++ b/litellm/litellm_core_utils/logging_utils.py
@@ -161,16 +161,14 @@ async def truncate_base64_in_messages_async(
     messages: str | list | dict | None,  # mutable-ok: same contract as truncate_base64_in_messages
 ) -> str | list | dict | None:  # mutable-ok: same contract as truncate_base64_in_messages
     """
-    Same result as truncate_base64_in_messages, but payloads with a data URI whose
-    string content reaches BASE64_TRUNCATION_OFFLOAD_THRESHOLD_CHARS are scanned in a
-    worker thread so the regex pass over multi-MB base64 images does not block the event loop.
+    Same result as truncate_base64_in_messages, but payloads whose string content
+    reaches BASE64_TRUNCATION_OFFLOAD_THRESHOLD_CHARS are scanned in a worker
+    thread so the regex pass over multi-MB base64 images does not block the event loop.
     """
     if messages is None or MAX_BASE64_LENGTH_FOR_LOGGING <= 0:
         return messages
-    leaves: Final = tuple(_iter_string_leaves(messages))
-    if sum(len(leaf) for leaf in leaves) < BASE64_TRUNCATION_OFFLOAD_THRESHOLD_CHARS or not any(
-        _may_contain_base64_data_uri(leaf) for leaf in leaves
-    ):
+    total_chars: Final = sum(len(leaf) for leaf in _iter_string_leaves(messages))
+    if total_chars < BASE64_TRUNCATION_OFFLOAD_THRESHOLD_CHARS:
         return truncate_base64_in_messages(messages)
     return await asyncio.to_thread(truncate_base64_in_messages, messages)
 
diff --git a/tests/unit/litellm_core_utils/test_logging_utils.py b/tests/unit/litellm_core_utils/test_logging_utils.py
index 69bec2cba63..7a035c79a42 100644
--- a/tests/unit/litellm_core_utils/test_logging_utils.py
+++ b/tests/unit/litellm_core_utils/test_logging_utils.py
@@ -323,16 +323,11 @@ class TestTruncateBase64InMessagesAsync:
         ],
         ids=["json_rows", "sse_lines", "code_with_semicolons", "sse_lines_with_semicolons", "base64_marker_without_data"],
     )
-    @pytest.mark.parametrize(
-        "truncate",
-        [lambda messages: _run_without_yielding(truncate_base64_in_messages_async(messages)), truncate_base64_in_messages],
-        ids=["async", "sync"],
-    )
-    def test_tool_message_without_data_uri_is_copied_inline_without_a_regex_scan(self, row, truncate):
+    def test_tool_message_without_data_uri_is_copied_without_a_regex_scan(self, row):
         tool_output = (row * (_PLAIN_TOOL_OUTPUT_CHARS // len(row) + 1))[:_PLAIN_TOOL_OUTPUT_CHARS]
         messages = _tool_result_messages(tool_output)
 
-        result, regex_calls = _regex_calls_while(lambda: truncate(messages))
+        result, regex_calls = _regex_calls_while(lambda: truncate_base64_in_messages(messages))
 
         assert result == messages
         assert result is not messages
@@ -351,15 +346,15 @@ class TestTruncateBase64InMessagesAsync:
         assert "base64_data truncated" in result[0]["content"][1]["image_url"]["url"]
 
     @pytest.mark.asyncio
-    async def test_small_data_uri_beside_large_text_is_scanned_off_the_event_loop(self, monkeypatch, scan_threads):
+    async def test_large_plain_text_is_copied_off_the_event_loop(self, monkeypatch, scan_threads):
         monkeypatch.setattr(logging_utils, "BASE64_TRUNCATION_OFFLOAD_THRESHOLD_CHARS", 1_000)
-        payload = "M" * 200
-        messages = _image_messages(payload) + _tool_result_messages("plain tool output\n" * 100)
+        messages = _tool_result_messages("plain tool output\n" * 100)
 
         result = await truncate_base64_in_messages_async(messages)
         offload_threads = tuple(scan_threads)
 
-        assert payload not in result[0]["content"][1]["image_url"]["url"]
+        assert result == messages
+        assert result is not messages
         assert offload_threads
         assert threading.get_ident() not in offload_threads