Prometheus provides JMX exporter which can export JVM information.

1. Create JMX exporter configuration. Let's call itjmx_exporter_config.yml.

---rules:-pattern:"java.lang.*"

2. Download JMX exporter

You can find the URL of JMX exporter jar file in Github repository.

https://github.com/prometheus/jmx_exporter

Here is the URL for 0.16.1

https://repo1.maven.org/maven2/io/prometheus/jmx/jmx_prometheus_javaagent/0.16.1/jmx_prometheus_javaagent-0.16.1.jar

3. Start your Java application

For example, your application is packaged as a jar filemyapp_1.jar.jmx_prometheus_javaagent-0.16.1.jar andjmx_exporter_config.yml are saved in/app. We expose port8080 to export metrics.

java-javaagent:/app/jmx_prometheus_javaagent-0.16.1.jar=8080:/app/jmx_exporter_config.yml-jar myapp_1.jar

4. Download Prometheus

You can find the URL of Prometheus in its official site.

https://prometheus.io/download/

Here is the URL of 2.33.0 (MacOS).

https://github.com/prometheus/prometheus/releases/download/v2.33.0/prometheus-2.33.0.darwin-amd64.tar.gz

5. Unzip Prometheus

After it is downloaded, unzip it and go to its directory.

tarxvfz prometheus-*.tar.gzcdprometheus-*

6. Update prometheus configuration

Add the following to theprometheus.yml (underscrape_configs). We adds label to help querying.

-job_name:"apps"static_configs:-targets:["localhost:8080"]labels:instance:'myapp_1'

The whole file should look like this.

# my global configglobal:scrape_interval:15s# Set the scrape interval to every 15 seconds. Default is every 1 minute.evaluation_interval:15s# Evaluate rules every 15 seconds. The default is every 1 minute.# scrape_timeout is set to the global default (10s).# Alertmanager configurationalerting:alertmanagers:-static_configs:-targets:# - alertmanager:9093# Load rules once and periodically evaluate them according to the global 'evaluation_interval'.rule_files:# - "first_rules.yml"# - "second_rules.yml"# A scrape configuration containing exactly one endpoint to scrape:# Here it's Prometheus itself.scrape_configs:# The job name is added as a label `job=<job_name>` to any timeseries scraped from this config.-job_name:"prometheus"# metrics_path defaults to '/metrics'# scheme defaults to 'http'.static_configs:-targets:["localhost:9090"]-job_name:"apps"static_configs:-targets:["localhost:8080"]labels:instance:'myapp_1'

7. Start Prometheus

./prometheus--config.file=prometheus.yml

8. Query JVM information

http://localhost:9090/

Queryjvm_memory_bytes_used{area="heap",instance="myapp_1"}

Here is the query result.

Or you prefer a graph (You may need to refresh the browser if you want to see the latest data)

Here are other metrics you can try.

• jvm_gc_collection_seconds_count

• jvm_gc_collection_seconds_sum

• jvm_memory_bytes_used -

• jvm_memory_bytes_committed

• jvm_memory_bytes_max

• jvm_memory_bytes_init

• process_cpu_seconds_total