title: ob_gzhandler returns blank pages when no session exists
body: <p>I wanted to compress my pages so I put</p>
  
  <pre><code>ob_start('ob_gzhandler');
  </code></pre>
  
  <p>at the beginning of my php header file. however as I was playing around I noticed it will give me a blank page if I start a session while the ob_gzhandler was not being used!
  so I did the below and it worked:</p>
  
  <pre><code>&lt;?php
    if (session_id() === null ) ob_start('ob_gzhandler');
  ?&gt;
  </code></pre>
  
  <p>how ever I'm not sure if this will always use the compression as I imagine their might be a session but the browser will still receive uncompressed data! I guess I would have to restart session if the scenario happens which really shouldnt other than development time. but I guess what I really want to know is some quick tips about zlib and this compression. Is there any performance tips? I assume the server output the internal buffer if there is no indication at end of file but should I put one there? ob_end_flushob_end_clean?ob_end_close?</p>
  
  <p>any notes on using memcache with this? any tips and info would be highly appreciated! </p>