title: When I increase sidekiq concurrency, it says my pool is too small. But smaller number works
body: <p>I'm a bit new to sidekiq but I managed to get it working pretty fine recently. However, I noticed that I needed to increase my concurrency from 5 to maybe 20-25. When I edited my <code>sidekiq.yml</code> file, which shows this:</p>
  
  <pre><code>development:  
    :concurrency: 5
  production:  
    :concurrency: 20
  :queues:
    - default
  </code></pre>
  
  <p>from 5 to 25, it threw me an error stating:</p>
  
  <blockquote>
    <p>Your Redis connection pool is too small for Sidekiq to work. Your pool
    has 20 connections but really needs to have at least 27</p>
  </blockquote>
  
  <p>What exactly is this error referring to? I even changed the "production" from 20 to 30, and it still claimed that my pool has 20 connections. </p>
  
  <p>If I'm increasing the concurrency, why is it <em>smaller</em> all of a sudden? Any clarification would be greatly appreciated.</p>