Should I close logger file?

Question

I've just read the Logger gem documentation and the method close called my attention. Now I'm wondering if I have to close logger file after using it, like:

log = Logger.new("foo.log")
# program here logging things
log.close

I've never closed it before and it doesn't seem to be an issue, maybe it's closed automatically when the program finishes?

Answer 1

TL;DR: you should not unless you know for sure you should.

The Logger has a LogDevice that might be any device: a file, a port, a socket, a pipe. Some devices are known to be fine with a concurrent access, but most of them are not. E.g. if you have a socket as a logging device, any other attempt to write to this socket will be prevented by OS. Concurrent writing to files, though possible in general, is not advised, because you’ll end up having a messed chunks there.

Unless you expect some other application is going to access the same device for writing, you are safe not closing the device. It’ll be closed automatically when the Logger is GC’ed.

On the other hand, if you are writing to the shared file, or expect that the destination might be used by 3rd parties during your program is alive, it’s safer to close the device once it becomes unneeded to allow concurrent access to it for the other writers.

NB: Logger#close actually closes the underlying device:

# File logger.rb, line 569
def close
  @logdev.close if @logdev
end