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Rohit is an investor, startup advisor and an Application Modernization Scale Specialist working at Google.

Wednesday, April 1, 2020

Start your Spring Apps in Milliseconds on Seconds


If you want to start your app as quickly as possible (most people do) there are some tweaks you might consider. Here are some ideas:
  • Use the spring-context-indexer (link to docs). It’s not going to add much for small apps, but every little helps.
  • Don’t use actuators if you can afford not to.
  • Use Spring Boot 2.1 and Spring 5.1.
  • Fix the location of the Spring Boot config file(s) with spring.config.location (command line argument or System property etc.).
  • Switch off JMX - you probably don’t need it in a container - with spring.jmx.enabled=false
  • Run the JVM with -noverify. Also consider -XX:TieredStopAtLevel=1 (that will slow down the JIT later at the expense of the saved startup time).
  • Use the container memory hints for Java 8: -XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap. With Java 11 this is automatic by default.
Your app might not need a full CPU at runtime, but it will need multiple CPUs to start up as quickly as possible (at least 2, 4 are better). If you don’t mind a slower startup you could throttle the CPUs down below 4. If you are forced to start with less than 4 CPUs it might help to set -Dspring.backgroundpreinitializer.ignore=true since it prevents Spring Boot from creating a new thread that it probably won’t be able to use (this works with Spring Boot 2.1.0 and above).

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