pre>
<p>If the model uses within-chain parallelization (<code>map_rect</code> or <code>reduce_sum</code> calls), the threads are automatically
scheduled to run the parallel parts of a single chain or run the sequential parts of another chains. The below
call starts 4 chains that can use 16 threads. At a given moment a single chain may use all 16 threads,
1 thread, anything in between, or can wait for a thread to be available. The scheduling is left to the <a href="https://software.intel.com/content/www/us/e