title: Boost::log stops logging right after initialization
body: <p>I have a small project that uses boost::log version 2 (from Boost 1.55). I want to log to a file, so I initialize it like this :</p>
  
  <pre><code>void initializeLogging(boost::log::trivial::severity_level level)
  {        
      logging::add_common_attributes();                                                              
  
      logging::add_file_log(
          keywords::file_name = "sample.%02N.log", 
          keywords::open_mode = std::ios::app,
          keywords::format = "[%TimeStamp%] %Message%"
      );
  
      logging::core::get()-&gt;set_filter
      (
          logging::trivial::severity &gt;= level
      );
  
      boost::log::sources::severity_logger&lt; boost::log::trivial::severity_level &gt; lg;
  
      BOOST_LOG_SEV(lg, boost::log::trivial::error) &lt;&lt; "INSIDE An error severity message";
  }
  </code></pre>
  
  <p>I see the line <code>INSIDE An error severity message</code> in the file sample.00.log.</p>
  
  <p>But when I call <code>doStuff</code>, right after, <code>initializeLogging</code> nothing is logged.</p>
  
  <pre><code>void doStuff()
  {
      boost::log::sources::severity_logger&lt; boost::log::trivial::severity_level &gt; lg;
  
      BOOST_LOG_SEV(lg, boost::log::trivial::error) &lt;&lt; "An error severity message";
  }
  </code></pre>
  
  <p>This code is in a Windows program, there is no console at can look at. There is nothing in Windows Debug log either.</p>
  
  <p>As you can see, <code>doStuff</code> has the exact same code as in the first function. Is there something I need to do to make my logging settings permanent?</p>