Stream Not Closed (ARCH6081)

Key ruby.performance.stream-not-closed · Severity warning · Category performance

A stream or reader opened without a scoped close block leaks file descriptors. Open the stream with the block form.

Incorrect

def read_lines(path)
  io = File.open(path)
  io.readlines
end

Correct

def read_lines(path)
  File.open(path) do |io|
    io.readlines
  end
end

Fix

Open streams and IO handles with the block form so they close automatically when the block ends.