This feature is experimental and is not supported out of the box for Gerrit monitoring on Jetty.
Background: JavaMelody only supports JNDI DataSource in Web container (Tomcat). Because Gerrit instantiates its data source on its own, JavaMelody can not intercept it and therefore no SQL statistic reports can be gathered.
To overcome that problem a data source proxy must be installed. Because the instantiation of the data source takes place in Gerrit core, it must be patched.
Next problem: JavaMelody JARs (that creates the data source proxies) must be available in the bootstrap classpath for Gerrit core to load it.
Last problem: we shouldn't package the plugin dependencies inside the plugin itself (shaded jar in Maven jargon) and in $gerrit_site/lib. We would need to strip it from the plugin.
Cherry-pick this change and compile Gerrit:
https://gerrit-review.googlesource.com/#/c/52747
Add the following target to BUCK in javamelody plugin:
gerrit_plugin(
name = 'javamelody-no-deps',
srcs = glob(['src/main/java/**/*.java']),
resources = glob(['src/main/resources/**/*']),
manifest_entries = [
'Gerrit-PluginName: javamelody',
'Gerrit-Module: com.googlesource.gerrit.plugins.javamelody.Module',
'Gerrit-HttpModule: com.googlesource.gerrit.plugins.javamelody.HttpModule',
],
compile_deps = [
'//plugins/javamelody/lib:javamelody',
'//plugins/javamelody/lib:jrobin',
],
)
Compile the plugin without dependencies:
buck build plugins/javamelody:javamelody-no-deps
Copy the dependencies manually to $gerrit_site/libs:
cp ~/.gerritcodereview/buck-cache/jrobin-1.5.9.jar-bd9a84484c67de930fa841f23cd6a93108b05cd0 $gerrit_site/lib/jrobin.jar cp ~/.gerritcodereview/buck-cache/javamelody-core-1.48.0.jar-4c573306061019430a735d9d58f93639f4a0ff0b $gerrit_site/lib/javamelody.jar
Deploy plugin without dependencies:
cp buck-out/gen/plugins/javamelody/javamelody-no-deps.jar $gerrit_site/plugins
Run Gerrit@Jetty and enjoy SQL statistics, a lá:
