Performance Wise, Python VS JAVA For File Based Processing
Performance-wise, for an I/O - syscall bound task such as you're mentioning, it's going to be a wash, most likely, depending a bit on the platform.  Java tends to have better CPU usage (partly because a JVM can effectively use multiple cores on a multicore CPU on different threads, with CPython having problems with that; partly because of strong JIT abilities), but typically pays for them with higher RAM footprints (no big deal if you have 64GB of RAM laying around and not much else to do on the machine, say, but often an issue in other circumstances).
If you specify the platform (Linux vs Windows vs ...), we might be able to offer more help.
Edit: with processing required as light as the OP's mentioned in the Q's edit, there's really nothing either way in the CPU-load part of the task.  Unfortunately I don't know what freebsd offers for "directory watching" (like Linux's inotify, etc).
I need to create daemon that will monitor certain directory and will process every file that's written to that particular path.
My choice is either java or python.
Did you guys have any experience using both technology? what is the best one?
EDIT 1: files that will be processed is simple text file  (one line with tab separated fields).
I just need to move it to buffer and send to further to my php file.
EDIT 2: It's for freebsd server