rav121 / java-docker

Docker & Java

This repo contains demo materials for:

• Tips minimize java containers images
• Tricks for fast startup java apps running in containrs
• gotchas and issues while running java apps in containers and the improvements that has been made

The repo is splitte into multiple branchs, each contains a specific topic. The Dockerfiles uses the generated jar after running the build (mvn clean package). The build step could be integrated in the provided Dockerfiles, but it would slow the demoing the intetntion of this repo, so I kept it outside. Below branch details:

• master: simple netty app, running in a container
• cdc: This showcase the class data sharing (CDS) feature. CDC offers dynamic sharing of data between multiple Java Virtual Machines (JVM), which helps to reduce the startup time and memory footprint.
• aot: Using Ahead Of Time compilation. It compiles the bytecode such that it is completely static which should lead to the fastest startup and initial execution speed.
• graal: This part uses graal VM to create native images for existing JVM-based applications.
• sb: This branch contains a simple instructions to run the petclinic application and test how it behaves running inside a java 8 docker container, and java 11!

Benchmarking

the bench.sh run each container and print at the end the total size of the image + the time it takes for teh container to run! for me I named the images: plain, cdc,aot,graal and mod. I prefixed each of them with dc! Executing the scripts shows below results in my machine:

Image   size        Startup
aot     463.864MB   654 ms
cdc     443.183MB   689 ms
plain   425.875MB   740 ms
mod     55.6048MB   686 ms
graal   9.49464MB   78 ms