title: Read txt file without lock in python
body: <p>I am copying the new content of a .txt source file to another with the use of an offset.</p>
  <pre><code>with open(source, &quot;rb&quot;) as infile:
              infile.seek(offset)
              data = infile.read()
  with open(destination, &quot;ab&quot;) as outfile:
              outfile.write(data)
  </code></pre>
  <p>Meanwhile, the source file can be updated (new rows added). Can a problem appear with this implementation ? This code could lock the source file ?
  This script runs every n seconds and the source file updates can be made at any time.</p>