title: Performance issues with Spring Boot 2.x?
body: <p>I recently updated the version of Spring Boot used in a web application from version 1.5 to 2.1.  When I ran the load tests against it, my run times went from 25 minutes to 35 minutes.</p>
  
  <p>I know it is a broad question, but does anyone have any clues as to why the application would slow down so dramatically after upgrading the Spring Boot libraries?</p>
  
  <p>EDIT:  After spending a lot of time trying to understand profiler ouput, The  problem appears to be in the communication to the database.  The Mariadb JDBC driver calls java.io.FilterInputStream.read to get data back from the database. According to the profiler, the application spends nearly twice as long in this method when running in Spring Boot 2 as it did in Spring Boot 1 (using Hikari for both).  Same application.  Same Database.  Same mariadb drivers.  Only the version of Spring changed, and whatever Spring brought in (like tomcat 9 instead of 8, or hibernate 5.3 instead of hibernate 5.0)</p>
  
  <p>EDIT #2: I've done some more testing.  I ran Spring Boot 2.1 with a downgraded Tomcat (8.5.37), and the performance remained bad, so it would seem that Tomcat is not the issue.  Next, I ran Spring Boot 1.5 with an upgraded Hibernate (5.3.10), and performance remained good, so it would seem that Hibernate isn't the issue either.  That doesn't leave much other than spring boot itself, and it remains a complete mystery to me why a class in java.io would take longer under one framework than another.</p>
  
  <p>This is preventing me from moving forward Spring Boot updates to production, so I appreciate any pointers you have,</p>
  
  <p>Steve</p>