Using Tomcat Native in Grails 3

March 27, 2018


Tomcat Native is a set of native extensions that can improve performance and compatibility - best said directly from the docs:

The Apache Tomcat Native Library is an optional component for use with Apache Tomcat that allows Tomcat to use certain native resources for performance, compatibility, etc.

Specifically, the Apache Tomcat Native Library gives Tomcat access to the Apache Portable Runtime (APR) library’s network connection (socket) implementation and random-number generator. See the Apache Tomcat documentation for more information on how to configure Tomcat to use the APR connector.

Features of the APR connector:

Non-blocking I/O for Keep-Alive requests (between requests)

Uses OpenSSL for TLS/SSL capabilities (if supported by linked APR library)

FIPS 140-2 support for TLS/SSL (if supported by linked OpenSSL library)

Grails uses Tomcat as it’s default container and if you’ve ever turned up logging while starting your Grails app you may have seen:

The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path

Well of course I want optimal performance in my production environment!

Installing Tomcat native

These days most distributions come with a tomcat-native package. All you need to do is install and configure it.


In our Grails application we will need to customize the embedded Tomcat to enable apr. We can add this little snipit to our Application.groovy class to add the APR connector:


EmbeddedServletContainerFactory servletContainer() {

    TomcatEmbeddedServletContainerFactory container = new TomcatEmbeddedServletContainerFactory()
LifecycleListener arpLifecycle = new AprLifecycleListener()





Install native extensions

To take advantage of APR we need to install the platform specific package.

  • Mac

    • brew install tomcat-native

  • Centos/Amazon/RedHat

    • yum install tomcat-native

Adding it to your JVM_OPTS

If your distributions doesn’t install it in the "default" library path (eg: homebrew), you’ll have to add it to your JVM opts:

bootRun {

  jvmArgs('-Dspring.output.ansi.enabled=always', '-Djava.library.path=/usr/local/opt/tomcat-native/lib')

  addResources = true


Or the JVM opts you use when starting tomcat on your server.

Is it working?

If you see the http-apr protocols starting, you’ll know it’s working:

Initializing ProtocolHandler ["http-apr-8080"]
Starting ProtocolHandler ["http-apr-8080"]


Tomcat-native provides some performance improvements and is not to difficult to setup. Always do your own benchmarks and testing to see if it provides you with a performance boost.