Spring-boot slow to start

Question

When I launch my jhipster app using "mvn spring-boot:run", it takes up to 60 seconds to start... First part of my log is :

[INFO] Scanning for projects...
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] Building jhipster 0.0.1-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO]
[INFO] >>> spring-boot-maven-plugin:1.1.9.RELEASE:run (default-cli) @ jhipster >>>
[INFO]
[INFO] --- maven-enforcer-plugin:1.3.1:enforce (enforce-versions) @ jhipster ---
[INFO]
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ jhipster ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 4 resources
[INFO] Copying 22 resources
[INFO]
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ jhipster ---
[INFO] Nothing to compile - all classes are up to date
[INFO]
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ jhipster ---
[INFO] Using 'UTF-8' encoding to copy filtered resources.
[INFO] Copying 3 resources
[INFO]
[INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ jhipster ---
[INFO] Nothing to compile - all classes are up to date
[INFO]
[INFO] <<< spring-boot-maven-plugin:1.1.9.RELEASE:run (default-cli) @ jhipster <<<
[INFO]
[INFO] --- spring-boot-maven-plugin:1.1.9.RELEASE:run (default-cli) @ jhipster ---
[INFO] Attaching agents: []
Listening for transport dt_socket at address: 5005

--> Then it hangs for around 30 seconds before continuing :

[INFO] com.mycompany.myapp.Application - Starting Application on MacBook-Pro.local with PID 5130 (/Users/othomas/Developpement/jhipster-1.9.0/target/classes started by othomas in /Users/othomas/Developpement/jhipster-1.9.0)
[DEBUG] com.mycompany.myapp.Application - Running with Spring Boot v1.1.9.RELEASE, Spring v4.0.8.RELEASE
[DEBUG] org.jboss.logging - Logging Provider: org.jboss.logging.Log4jLoggerProvider

...

I remember having used older versions of jhipster generator (0.17 etc) et it started in 15-20 seconds. Is it normal or is there a problem on my side ? Where to look for ?

Thanks, O.

Answer 1

I've been suffering slow startup times myself and wondering what the cause was. I get all the console messages saying various things have started and then it hangs just before the final message to say the app has loaded.

Eventually I found I could use Java VisualVM as part of the JDK to see what was going on. If you have the jdk installed its jvisualvm.exe in the bin folder. Then when I select to debug as Application.java the tomcat process pops up and you can track what's going on.

I took a couple of thread dumps where it hangs and it always seemed to be where the swagger API docs are being generated. A bit more digging and this is configured in a class called MetricsConfiguration which is excluded if you run with a profile called "fast".

In eclipse I edited my debug configuration to include a program argument of:

--spring.profiles.active=dev,fast

This cuts down the startup time from 230 seconds to just 25!

I had a quick scan and fast seems to disable all sorts of things. It mainly looks like the stuff under the admin menu which you'll probably not need during development anyway. Personally I would prefer a fast bootup to being able to see the rest docs during development.

Swagger being such a hog made me wonder if it's such a good idea after all. Is it worth the cost? i then read this http://java.dzone.com/articles/swagger-great and I'm considering just removing it altogether. It's a nice idea but seems to add 33mb to the build + for me was causing really slow startup times.

For info I have around 16 entities. So not small but not excessively large either.

Answer 2

Make sure you aren't running the server in debug mode and have a breakpoint set. This reduced the startup time of one of my applications from 3 min to 22 sec.