title: R future multisession limiting number of cpus
body: <p>I'm currently parallellising by using the future package as follows:</p>
  
  <pre><code>plan(multisession, gc = TRUE)
  standardised_addresses1 &lt;- future_lapply(1:20000, function(x) x*x) 
  </code></pre>
  
  <p>The problem is that it uses all the CPUs on the server.
  I would like to limit the number of CPUs used by setting a parameter like:
  workers = 18</p>