This is mostly to help other people as we are probably just going to move away from log4r to syslog or something. We have a project which uses log4r with the RollingFileOutputter. The latest log is not growing in size but instead being overwritten frequently. I believe this is the due to the fact that log4r is opening it in write mode instead of append mode.
$ lsof +fg |grep silo.production | grep -v W,AP
ruby 10894 seomoz 13w REG W,0x8000 252,0 3318 527976 /var/www/vhosts/silo/shared/log/silo.production000235.log
ruby 15449 seomoz 13w REG W,0x8000 252,0 4368 527976 /var/www/vhosts/silo/shared/log/silo.production000235.log
ruby 15909 seomoz 13w REG W,0x8000 252,0 4504 527976 /var/www/vhosts/silo/shared/log/silo.production000235.log
ruby 16020 seomoz 13w REG W,0x8000 252,0 4504 527976 /var/www/vhosts/silo/shared/log/silo.production000235.log
ruby 16122 seomoz 13w REG W,0x8000 252,0 4504 527976 /var/www/vhosts/silo/shared/log/silo.production000235.log