[3.11] pythongh-89047: Fix msecs computation so you never end up with 1000 msecs. (pythonGH-96340) (pythonGH-96341)

Author: miss-islington

Lib/logging/__init__.py

@@ -334,7 +334,7 @@ def __init__(self, name, level, pathname, lineno,
         self.lineno = lineno
         self.funcName = func
         self.created = ct
-        self.msecs = (ct - int(ct)) * 1000
+        self.msecs = int((ct - int(ct)) * 1000) + 0.0  # see gh-89047
         self.relativeCreated = (self.created - _startTime) * 1000
         if logThreads:
             self.thread = threading.get_ident()

Lib/test/test_logging.py

@@ -4088,6 +4088,14 @@ class NoMsecFormatter(logging.Formatter):
         f.converter = time.gmtime
         self.assertEqual(f.formatTime(r), '21/04/1993 08:03:00')
 
+    def test_issue_89047(self):
+        f = logging.Formatter(fmt='{asctime}.{msecs:03.0f} {message}', style='{', datefmt="%Y-%m-%d %H:%M:%S")
+        for i in range(2500):
+            time.sleep(0.0004)
+            r = logging.makeLogRecord({'msg': 'Message %d' % (i + 1)})
+            s = f.format(r)
+            self.assertNotIn('.1000', s)
+
 
 class TestBufferingFormatter(logging.BufferingFormatter):
     def formatHeader(self, records):