simplify iso format to not use datetime

Author: gpshead

Lib/_colorize.py

@@ -17,6 +17,7 @@ class ANSIColors:
     BLUE = "\x1b[34m"
     CYAN = "\x1b[36m"
     GREEN = "\x1b[32m"
+    GREY = "\x1b[90m"
     MAGENTA = "\x1b[35m"
     RED = "\x1b[31m"
     WHITE = "\x1b[37m"  # more like LIGHT GRAY

Lib/test/test_traceback_timestamps.py

@@ -65,7 +65,8 @@ def test_traceback_timestamps_flag_iso(self):
         result = script_helper.assert_python_ok("-X", "traceback_timestamps=iso", self.script_path)
         stderr = result.err.decode()
         self.assertIn("<@", stderr)  # Timestamp should be present
-        self.assertRegex(stderr, r"<@\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}")  # ISO format
+        # ISO format with Z suffix for UTC
+        self.assertRegex(stderr, r"<@\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}\.\d{6}Z>")
 
     def test_traceback_timestamps_flag_value(self):
         """Test that sys.flags.traceback_timestamps shows the right value"""
@@ -147,4 +148,4 @@ def test_traceback_timestamps_invalid_flag(self):
 
 
 if __name__ == "__main__":
-    unittest.main()
+    unittest.main()

Lib/traceback.py

@@ -192,8 +192,13 @@ def _timestamp_formatter(ns):
             return f"<@{ns}ns>"
     case "iso":
         def _timestamp_formatter(ns):
-            from datetime import datetime
-            return f"<@{datetime.fromtimestamp(ns/1e9).isoformat()}>"
+            # Less logic in a critical path than using datetime.
+            from time import strftime, gmtime
+            seconds = ns / 1e9
+            # Use gmtime for UTC time
+            timestr = strftime("%Y-%m-%dT%H:%M:%S", gmtime(seconds))
+            fractional = f"{seconds - int(seconds):.6f}"[2:]  # Get just the decimal part
+            return f"<@{timestr}.{fractional}Z>"  # Z suffix indicates UTC/Zulu time
     case _:
         raise ValueError(f"Invalid sys.flags.traceback_timestamp={_TIMESTAMP_FORMAT!r}")