M Java application probably has a file descriptor leak, since I'm getting a Too many open files exception.
I'm running my application with JFR, and when I inspect File I/O I barely see any I/O count. Is it possible to use JFR for finding code which open files but not closes them?
No, JFR can't track file handles.
You can change the threshold of the File Read and File Write event to 0 ns, so you will see every read and write, but there will be a lot of events. Not sure if it will help though.
You can change the threshold in the Recording Wizard, or Window -> Template Manager if you don't start the recording from JMC.