In the previous blog post, I briefly introduced unified logging and a simple GC configuration. However for the savvy GC tuners, there are many more options. And there are other logging options that transitionned to unified logging infrastructure as well.
I wasn’t satisfied with the official documentation and other blog posts as they usually present only a fragmented picture of the previous options. This led me to dig in.
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Introduction to JVM Unified Logging (JEP-158 / JEP-271)
Unified logging was introduced in JDK 9, and is available for us all, in the JDK 11 LTS. Like other great serviceability feature (jcmd or JFR) this was inspired by JRockit.
In my opinion the flexibility of this logging system brought a major downside from a user’s perspective in its configuration correctness, and I think in some ways it’s more obscure compared to the previous explicit logging flags.