http://metrics.dropwizard.io

https://dropwizard.github.io/metrics

http://metrics.dropwizard.io/3.2.2/getting-started.html

api:
http://metrics.dropwizard.io/3.2.2/apidocs/

articles:
http://www.baeldung.com/dropwizard-metrics
https://blog.openshift.com/day-13-dropwizard-the-awesome-java-rest-server-stack/
https://www.stubbornjava.com/posts/monitoring-your-jvm-with-dropwizard-metrics
http://jansipke.nl/getting-metrics-from-the-java-virtual-machine-jvm/

src:
https://github.com/dropwizard/metrics
https://github.com/dropwizard/metrics/blob/master/metrics-jvm/

servlet:
https://ivanursul.com/monitoring-your-spring-application-using-dropwizard-metrics-module/

memory:
//Code-Cache Compressed-Class-Space Metaspace PS-Eden-Space PS-Old-Gen PS-Survivor-Space
http://docs.oracle.com/javase/8/docs/api/java/lang/management/MemoryPoolMXBean.html
http://docs.oracle.com/javase/8/docs/api/java/lang/management/MemoryMXBean.html
http://docs.oracle.com/javase/8/docs/api/java/lang/management/MemoryUsage.html
http://docs.oracle.com/javase/8/docs/api/java/lang/management/MemoryManagerMXBean.html
https://github.com/dropwizard/metrics/blob/master/metrics-jvm/src/main/java/io/dropwizard/metrics/jvm/MemoryUsageGaugeSet.java
https://github.com/dropwizard/metrics/blob/master/metrics-jvm/src/test/java/io/dropwizard/metrics/jvm/MemoryUsageGaugeSetTest.java

integrations:
http://metrics.ryantenney.com/
    https://ryanpmartz.com/booktrackr-part-08-monitoring
http://vertx.io/docs/vertx-dropwizard-metrics/java/