Log4j: How app.log and app.log.1 are written at same time?

[Samyuktha S Kumar]

Hi,

I have a web app running on tomcat. I have rolling file appender. I have configured log4j to write logs into say app.log
But I find that at a time app.log and app.log.1 are written at the same time.
I dont understand how this can be possible.
Please help

[Nam Ha Minh]

the file "app.log" is the current log, others are rolled files.

[Samyuktha S Kumar]

Then only app.log should be updated at current point of time. If the file exceeds the max limit size then it rolls over to the next file
But in this case both app.log and app.log.1. are updated at same time. They have logs with the same timestamp inside it

Is it like more than one process is writing log?

Our app is running on a cluster.

[Paul Clapham]

Yes, if you have more than one process writing to a file at the same time, strange things can happen.