Logging mingled | log4j

Question

Saw some strange logging in our application logs. We are using log4j. Does log4j allow printing logs which are interwoven in time. I mean like we have first the log with timestamp say 16:10:30 and then log having timestamp 16:10:25. Even if they are being printed by different thread. Isn't that some strange behaviour. Though log I am tracing is of the day when whole of application seems to have jammed up(After every regular interval log is missing for almost half a minute and then activity resumes and then outage for another half a minute).

Thanks, Mawia