Running GroovyShell.parse, common as part of form validation for plugins offering Groovy scripting, is unnecessarily slow:
java.lang.Thread.State: RUNNABLE
at java.lang.Throwable.fillInStackTrace(Native Method)
- locked <0x000000078fc42f48> (a java.lang.ClassNotFoundException)
at java.lang.Throwable.<init>(Throwable.java:218)
at java.lang.Exception.<init>(Exception.java:59)
at java.lang.ClassNotFoundException.<init>(ClassNotFoundException.java:65)
at jenkins.util.AntClassLoader.findClassInComponents(AntClassLoader.java:1375)
at jenkins.util.AntClassLoader.findClass(AntClassLoader.java:1325)
at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at jenkins.ClassLoaderReflectionToolkit.invoke(ClassLoaderReflectionToolkit.java:44)
at jenkins.ClassLoaderReflectionToolkit._findClass(ClassLoaderReflectionToolkit.java:86)
- locked <...> (a hudson.ClassicPluginStrategy$AntClassLoader2)
at hudson.PluginManager$UberClassLoader.findClass(PluginManager.java:1042)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
- locked <...> (a hudson.PluginManager$UberClassLoader)
at java.lang.ClassLoader.loadClass(ClassLoader.java:295)
- locked <...> (a groovy.lang.GroovyClassLoader)
at groovy.lang.GroovyClassLoader.loadClass(GroovyClassLoader.java:692)
at groovy.lang.GroovyClassLoader.loadClass(GroovyClassLoader.java:560)
at org.codehaus.groovy.control.ClassNodeResolver.tryAsLoaderClassOrScript(ClassNodeResolver.java:183)
at ...
at groovy.lang.GroovyClassLoader.parseClass(GroovyClassLoader.java:281)
- locked <...> (a java.util.HashMap)
at groovy.lang.GroovyShell.parseClass(GroovyShell.java:731)
at groovy.lang.GroovyShell.parse(GroovyShell.java:743)
at groovy.lang.GroovyShell.parse(GroovyShell.java:770)
Should cache negative class loads, since these are common when compiling Groovy at least.
Aggravated by JENKINS-23784: if one thread is holding the lock and taking its time, other threads can queue up rather than utilizing multiple cores.