If we ulimit the number file descriptors that can be open simulatanously and
set find to execute ls for every subdirectory (-execdir ls ’{}’ \;), it quickly
runs out of file descriptors. File descriptors are always opened (pred.c:520)
but never closed (pred.c:659-664) which raises an error when no more
descriptors are available (pred.c:579).

Example of Correct Fix: 
Close file descriptor as soon as it is not used anymore.

Example of Incorrect Fix: 
Close random file descriptor (Incomplete Fix because still leaking file
descriptors).