JVM vs Native - An effective comparison of performances

To compare the execution of a Java application between its Bytecode (JVM) and native (GraalVM) versions, you must first decide on its architecture and the framewoks to use. Secondly, we must also ask ourselves what we are going to measure.

Recently, I came across a very interesting course, containers and orchestration, by Jérôme Petazzoni . It uses different Python and Ruby applications which interact by means of Docker containers. They act as a mesh of microservices. The efficiency of the system is measured by the number of treatments performed per second.

It seemed like a good example to serve as a basis for this comparison by:

• Transposing the code into Java language under the Spring Boot / WebFlux frameworks and using Spring Native for the build in Bytecode or in native,
• Playing on the number of containers in order to vary the load of the system.

Let’s see this in detail.

• Requirements
• Application Architecture
• Build the app
  • Requirements for the build
  • The easy way
  • Summary of executed commands
  • From Docker Hub
  • Check
• Kubernetes configuration
  • Kubernetes Stack Architecture
• Grafana configuration
  • Data source configuration
  • Dashboard configuration
  • Description of the Demo Dashboard
• Starting the application
• Play with Kubernetes configuration
  • Overview
  • Increase pods’ number
  • Impact on the application
  • Further increase the number of pods
  • Let’s deploy the native version of the application
• Clean all
• Conclusion
• What next?
  • What is missing for a more realistic evaluation?
  • Useful links

Requirements

To implement this solution, we will need:

1. A Kubernetes cluster to run our containers,
2. Different processing measurements from microservices
3. Prometheus and Grafana to collect and display these measurements,
4. A Java application compilable in Bytecode and native

Well, that’s not much and it already exists:

• In a previous article, I explain how to install a complete Kubernetes, Prometheus and Grafana stack - Locally install Kubernetes, Prometheus, and Grafana,
• By integrating Micrometer with a Java Spring Boot application, it is possible to expose the measurements of its services - HasherHandler.java,
• For a Python application, the prometheus_client library also allows to expose measurements - worker.py,
• By configuring the Maven POM with the org.springframework.experimental:spring-native dependency, it is possible to compile the application in Bytecode as well as in native.

Application Architecture

Let’s see what the application is made of:

The application is made up of 4 microservices:

1. worker: the algorithm orchestrator [Python] which gets 1 a random number, 2 hash it and 3 increment a counter in the redis database,
2. rng: the random number generator [Java],
3. hasher: the hash processor [Java],
4. redis: the database which records a processing cycle counter.

Build the app

The purpose of the compilation is to produce one Docker image by microservice. For Java microservices, there will be two images, the first in Bytecode, the second in native.

Requirements for the build

However, if you want to create these Docker images, you will need to install:

• GraalVM 21.1.0 Java 11 based
• GraalVM Native Images
• Docker

The easy way

To do so, execute this script in the project root:

./build_docker_images.sh

Summary of executed commands

• For a non-java app:

docker build -t <app_docker_tag> ./<app_dir>

• For JVM-based image:

cd <app_dir>
mvn clean package
docker build -t <app_docker_tag> .

• For a Java native image:

cd <app_dir>
mvn spring-boot:build-image

From Docker Hub

You can pull pre-build images from Docker Hub by entering:

docker pull jeanjerome/rng-jvm:1.0.0
docker pull jeanjerome/hasher-jvm:1.0.0
docker pull jeanjerome/worker-python:1.0.0
docker pull jeanjerome/rng-native:1.0.0
docker pull jeanjerome/hasher-native:1.0.0

Check

To list your local docker images, enter:

docker images

At least, you should see these images in your local registry:

REPOSITORY                TAG        IMAGE ID       CREATED             SIZE
rng-jvm                   1.0.0      f4bfdacdd2a1   4 minutes ago       242MB
hasher-jvm                1.0.0      ab3600420eab   11 minutes ago      242MB
worker-python             1.0.0      e2e76d5f8ad4   38 hours ago        55MB
hasher-native             1.0.0      629bf3cb8760   41 years ago        82.2MB
rng-native                1.0.0      68e484d391f3   41 years ago        82.2MB

Kubernetes configuration

First, we need to define the kubernetes configuration of our application and tell Prometheus where to find the metrics.

Kubernetes Stack Architecture

Let’s see how to install these microservices in our kubernetes cluster:

• The architecture of the application is deployed in a dedicated namespace, demo,
• The monitoring tools are in another namespace called monitoring.

1. We want to manage the number of containers - pods in this case - for each microservice,

2. We also want to be able to change the pod image (Bytecode or native) without needing to redeploy everything.

   => Such Kubernetes resource already exists, Deployment

3. We need our microservices to communicate with each other in the Kubernetes cluster.

   => This is the job of the resource Service.

4. The Redis database does not need to be accessible from outside, only from inside the cluster.

   => This is already the case because, by default, Kubernetes Services are of type ClusterIP.

5. We want application metrics to be collected by Prometheus.

   => Here is how to configure it

Take a look at the Hasher microservice configuration below:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: hasher
  namespace: demo
  labels:
    app: hasher
spec:
  replicas: 1
  selector:
    matchLabels:
      app: hasher
  template:
    metadata:
      name: hasher
      labels:
        app: hasher
    spec:
      containers:
        - image: hasher-jvm:1.0.0
          imagePullPolicy: IfNotPresent
          name: hasher
          ports:
            - containerPort: 8080
              name: http-hasher
              protocol: TCP
          readinessProbe:
            failureThreshold: 3
            httpGet:
              path: /actuator/health
              port: 8080
              scheme: HTTP
            initialDelaySeconds: 10
            periodSeconds: 30
            successThreshold: 1
            timeoutSeconds: 2
---
apiVersion: v1
kind: Service
metadata:
  name: hasher
  namespace: demo
  labels:
    app: hasher
  annotations:
    prometheus.io/scrape: 'true'
    prometheus.io/scheme: http
    prometheus.io/path: /actuator/prometheus
    prometheus.io/port: '8080'
spec:
  ports:
    - port: 8080
      protocol: TCP
      targetPort: http-hasher
  selector:
    app: hasher

Grafana configuration

To display the metrics collected by Prometheus, Grafana needs:

• A data source to Prometheus,
• A dashboard describing the metrics to display and in what form.

Data source configuration

Grafana uses YAML files to configure a data source. It can be defined using the Kubernetes ConfigMap resource:

apiVersion: v1
kind: Namespace
metadata:
  name: monitoring
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: grafana-datasources
  namespace: monitoring
data:
  prometheus.yaml: |-
    {
        "apiVersion": 1,
        "datasources": [
            {
               "access":"proxy",
                "editable": true,
                "name": "prometheus",
                "orgId": 1,
                "type": "prometheus",
                "url": "http://prometheus-service.monitoring.svc:8080",
                "version": 1
            }
        ]
    }

It remains to pass this resource to Grafana in the definition of its Deployment:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: grafana
  namespace: monitoring
spec:
  replicas: 1
  template:
    spec:
      containers:
        - image: grafana/grafana:latest
          name: grafana
.../...
          volumeMounts:
            - mountPath: /etc/grafana/provisioning/datasources
              name: grafana-datasources
              readOnly: false
      volumes:
        - name: grafana
          emptyDir: {}
        - name: grafana-datasources
          configMap:
            defaultMode: 420
            name: grafana-datasources

Dashboard configuration

1. Connect to the Grafana web interface,
2. Import the pre-defined dashboard demo-dashboard.json,
3. Display the dashboard.

You should see an empty dashboard as follows:

Description of the Demo Dashboard

• The rows of the table (labeled from A to C) represent the 3 microservices, respectively, Worker, Random Number Generator -RNG- and Hasher.

• The columns (numbered 1 to 4) represent different metrics:

  • In column 1, we can see the number of pods running as well as the speed of the processes
  • In column 2 is displayed the history of processing speeds, for each microservice,
  • In column 3 the CPU consumption of each pod is displayed,
  • In column 4, the RAM consumption of each pod.

Starting the application

A Kubernetes configuration was created with Replicas of 1 pod for each microservice and Java images compiled in Bytecode.

• To start the application in Kubernetes, enter:

kubectl apply -f _kube/k8s-app-jvm.yml

• You should see the output:

namespace/demo created
deployment.apps/hasher created
service/hasher created
deployment.apps/rng created
service/rng created
deployment.apps/redis created
service/redis created
deployment.apps/worker created
service/worker created

• Visualize the start of the pods in Grafana:

Play with Kubernetes configuration

Overview

• Let’s see the actual deployment’s situation by entering:

kubectl get deployment -n demo

• Which should return:

NAME     READY   UP-TO-DATE   AVAILABLE   AGE
hasher   1/1     1            1           13m
redis    1/1     1            1           13m
rng      1/1     1            1           13m
worker   1/1     1            1           13m

Increase pods’ number

• To scale up worker pods to 2, enter:

kubectl scale deployment worker --replicas=2 -n demo

• Which returns:

deployment.apps/worker scaled

Impact on the application

• Let’s take a look at the Grafana dashboard:

Further increase the number of pods

• Let’s go to 10 workers:

kubectl scale deployment worker --replicas=10 -n demo

• Let’s increase hasher and rng pods’ number:

kubectl scale deployment hasher rng --replicas=5 -n demo

Let’s deploy the native version of the application

• Replace the current image of the pods with their native version by updating their Deployment:

kubectl set image deployment/hasher hasher=hasher-native:1.0.0 -n demo
kubectl set image deployment/rng rng=rng-native:1.0.0 -n demo

• Watch the rollout:

kubectl rollout status deployment/hasher -n demo

• And open the Grafana dashboard:

Clean all

• To simply remove the app and all its microservices, enter:

kubectl delete -f _kube/k8s-app-jvm.yml 

• which will remove all the Kubernetes configuration created previously:

namespace "demo" deleted
deployment.apps "hasher" deleted
service "hasher" deleted
deployment.apps "rng" deleted
service "rng" deleted
deployment.apps "redis" deleted
service "redis" deleted
deployment.apps "worker" deleted
service "worker" deleted

Conclusion

We learned how to install a full Kubernetes stack so that we can measure application metrics.

However, we are not getting the results we expect in the context of native applications. One explanation could be a lack of the Spring Beta version: Spring Native has just upgraded to version 0.10.0-SNAPSHOT and this is precisely the version where performance improvements are planned.

I’ll open a ticket with the Spring Boot team to ask for their analysis.

What next?

What is missing for a more realistic evaluation?

• Kubernetes configuration should always include a resource limit which has not been done in this demo.
• I could have used Horizontal Pod Autoscaler (HPA) and even better HPA on custom metrics (read this post for more details).

Useful links

Here are some links for further reading:

• Jérôme Patazzoni’s container training: https://github.com/jpetazzo/container.training
• Kubernetes Concepts : https://kubernetes.io/docs/concepts/
• Monitoring your apps in Kubernetes with Prometheus and Spring Boot: https://developer.ibm.com/technologies/containers/tutorials/monitoring-kubernetes-prometheus/
• Prometheus Python Client: https://github.com/prometheus/client_python
• Custom Prometheus Metrics for Apps Running in Kubernetes: https://zhimin-wen.medium.com/custom-prometheus-metrics-for-apps-running-in-kubernetes-498d69ada7aa

Well, that’s your turn playing with native apps now!

Cheers…

Written by

Jean-Jerome Levy

DevOps Consultant

Seasoned professional in the field of information technology, I bring over 20 years of experience from working within major corporate IT departments. My diverse expertise has played a pivotal role in a myriad of projects, marked by the implementation of innovative DevOps practices.

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