title: What are PHP-FPM pools and what is pm.max_children?
body: <p>I have a Drupal site with NGINX and PHP-FPM with 3 pools. </p>
  
  <p>What I want to know is what are FPM pools or just give me links to good documentation, i've searched about this topic but all I found is how to configure "X" to obtain a better performance.</p>
  
  <p>Also, what is pm.max_children? I recently notice in the log that when pool www1 reaches this value the pool www1 stops working, locking also a page on my site until I reload PHP-FPM. Why I'm reaching pm.max_children after some time? Is there a way to detect and react in this event... reloading PHP-FPM? Is there a way to avoid reaching pm.max_children?</p>
  
  <p>Thanks all for your knowledge.</p>
  
  <p>PD: I'm using perusio's configuration for Drupal and Nginx.</p>