title: JMeter: the same UUID between several samplers
body: <p>How can a Jmeter thread group with several HTTP requests uses the same UUID value per thread?</p>
  
  <p>I've tried to create 'user defined variables' element with <code>${__UUID}</code> and java preprocessor with <code>vars.put("uuid", UUID.randomUUID().toString())</code>; (independently)</p>
  
  <p><a href="https://i.stack.imgur.com/JyaxT.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/JyaxT.png" alt="thread group"></a></p>
  
  <p>but every http request in the same thread using its own UUID.</p>