title: Activiti Rest - Calling multiple instances concurrently
body: <p>I have defined some simple BPM flows (F1) and deployed in activiti-rest.war. For simplicity, I have take a simple start-end flow.</p>
  
  <p>I have written a REST client to execute the flow (F1) in parallel threads (20) with its required parameters for 1000 http requests. </p>
  
  <p><strong>Problem:</strong> I can see the flows are running sequentially, one by one response for the 20 parallel threads. It took a time of around 60 secs to complete with 20 threads (even when increased to 50 threads) it is the same.</p>
  
  <p>Activiti Version : 5.15 
  What should be the problem here ?. Any help will be really useful.
  activiti-rest/service/runtime/process-instances - Rest URL used to start the instance</p>
  
  <p>Thanks,</p>
  
  <p>Yoka</p>