Issue #9512: Made comment more informative.
diff --git a/Lib/logging/handlers.py b/Lib/logging/handlers.py
index cda84e7..38beb10 100644
--- a/Lib/logging/handlers.py
+++ b/Lib/logging/handlers.py
@@ -108,8 +108,13 @@
If maxBytes is zero, rollover never occurs.
"""
+ # If rotation/rollover is wanted, it doesn't make sense to use another
+ # mode. If for example 'w' were specified, then if there were multiple
+ # runs of the calling application, the logs from previous runs would be
+ # lost if the 'w' is respected, because the log file would be truncated
+ # on each run.
if maxBytes > 0:
- mode = 'a' # doesn't make sense otherwise!
+ mode = 'a'
BaseRotatingHandler.__init__(self, filename, mode, encoding, delay)
self.maxBytes = maxBytes
self.backupCount = backupCount