We have recently experienced OutOfMemory errors on some large Jenkins instances that predominantly have frequently executed jobs that contain either System Groovy scripts or Build Flow project types. In one case after disabling a groovy script that was being executed via the Global Post Script Plugin after every build, the PermGen profile improved dramatically.

We tested further with GroovyShell to run a groovy script, not depending on Jenkins.
Java7: java.lang.OutOfMemoryError: PermGen space
Java8: java.lang.OutOfMemoryError: Java heap space

The tests use 2.4.6 version of groovy which is the latest version. However, the issue is still there.
<dependency>
<groupId>org.codehaus.groovy</groupId>
<artifactId>groovy-all</artifactId>
<version>2.4.6</version>
</dependency>

---------------------------------------
Configure 10 jobs which build per minute
Each build triggers a groovy script by Global Post Script Plugin.

class Main {
    static void main(String... args) {
        println 'Groovy world!'
        def p = new Person()
        p.write()
    }
}

class Person {
    def write(){
        println 'i am writing ...!'
    }
}

After sometime, the perm gen is eaten up. See the screenshot of jvisualvm.

I checked the source code of the plugin:
https://github.com/jenkinsci/global-post-script-plugin/blob/master/src/main/java/com/orctom/jenkins/plugin/globalpostscript/ScriptExecutor.java

My feeling is that it is probably caused by GroovyShell. Jenkins loads and runs groovy extensively and maybe there are places in core or other plugins having similar logic, I wonder
1. if this is a potential memory leak, and
2. if anyone has met similar issue.