title: Running parallel stages on node with one executor
body: <p>Suppose that I have one jenkins node with one executor and I have to run i.e. tests and build stages in parallel.</p>
  
  <pre><code>node("jenkinsNodeWithOneExecutor") {
  
      parallel {
          test: {echo "run test" ... }
          build: {echo "run build" ...}
      }
  
  }
  </code></pre>
  
  <p>How this will work? In the logs I see that that it runs parallel. Is it possible? I thought that every parallel task needs own executor... </p>
  
  <p>PS. When trying to run job twice: Waiting for next available executor on ...</p>