GlassFish in all it's logging and log rotation uses SimpleDateFormat which uses the Runtime default TimeZone. The issue here is that it is possible that applications may change the system default TimeZone and all the logging are then affected
a) The log file rotation dates may generated from SimpleDateFormat and hence, sudden changes may cause non-monotonic values.
b) Also logging date is not consistent (if this happens)
1. Calling TimeZone.setDefault(TimeZone.getTimeZone("Europe/London")) will cause all the new server.log to use UK as the timezone.
2. Then log some entries.
GlassFish should not be affected by the runtime change or changes
to TimeZone (for core services) [* note there is no security permission
to prevent one from doing this *]