It is important to ensure that files that are opened always get closed. Failing to close files can result in file descriptor leaks. You can detect a file descriptor leak in two different ways:
You may notice a lot of
IOExceptionswith the message “Too many open files.”During load testing, you periodically run a profiling script, such as
lsof(on UNIX), and you notice that the list of file descriptors grows continually.
File descriptor leaks can also lead to a variety of failures on attempts to open properties files, sockets, etc. If your error log contains a lot of chaotic-looking error messages, the presence of a file descriptor leak is one thing to check.
