Gernot Bauer created GROOVY-8035:
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Summary: Class unloading (PermGen) memory leak with Groovy Shell
Key: GROOVY-8035
URL: https://issues.apache.org/jira/browse/GROOVY-8035
Project: Groovy
Issue Type: Bug
Affects Versions: 2.4.7
Environment: Oracle JDK6, Oracle JDK7
Reporter: Gernot Bauer
The following code causes a memory leak in perm gen reproducibly on Oracle JDK6
and 7.
{code:java}
import groovy.lang.GroovyShell;
public class Demo {
public static void main(String[] args) throws Exception {
for (int i = 0; i < 10000000; i++) {
GroovyShell gs = new GroovyShell();
Object result = gs.evaluate(" 'Hello, World';");
assert result.equals("Hello, World");
}
}
}
{code}
Tested with the following VM options (with PermGen size 20MB), the execution
results in java.lang.OutOfMemoryError: PermGen space after a little more than
2000 iterations.
{noformat}
-verbose:class -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions
-XX:+CMSClassUnloadingEnabled -XX:+ExplicitGCInvokesConcurrentAndUnloadsClasses
-XX:+TraceClassUnloading -XX:MaxPermSize=16M -XX:+UseConcMarkSweepGC
-XX:+ExplicitGCInvokesConcurrent -XX:+PrintGCDetails -XX:-UseParNewGC
{noformat}
As a workaround, calling the following method with script.getClass() from above
(as described in http://stackoverflow.com/a/41473210/2156613) seems to avoid
this leak and trigger class unloading correctly:
{code:java}
public static void clearAllClassInfo(Class<?> type) {
try {
Field globalClassValue =
ClassInfo.class.getDeclaredField("globalClassValue");
globalClassValue.setAccessible(true);
GroovyClassValue classValueBean = (GroovyClassValue)
globalClassValue.get(null);
classValueBean.remove(type);
} catch (Exception ex) {
throw new RuntimeException(ex);
}
}
{code}
This should be handled by Groovy itself, or (if this is not possible) there
should be at least a possibility to trigger this functionality via a Groovy API
call instead of having to create the above method in all applications using
Groovy.
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