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https://issues.apache.org/jira/browse/GROOVY-11152?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Eric Milles updated GROOVY-11152:
---------------------------------
Language: groovy
> Indy churning through LambdaForm classes
> ----------------------------------------
>
> Key: GROOVY-11152
> URL: https://issues.apache.org/jira/browse/GROOVY-11152
> Project: Groovy
> Issue Type: Improvement
> Components: Compiler
> Affects Versions: 4.0.13
> Reporter: Oliver Gillespie
> Priority: Minor
>
> I observed an issue in my application where it is continuously churning
> (loading, then later unloading) LambdaForm MethodHandle classes.
> Note: some discussion on this in
> [https://lists.apache.org/thread/qmgsokwys9fkcozwq9vlmgnry14mdjwl].
> {code:java}
> [6.289s][info][class,init ] 2754 Initializing
> 'java/lang/invoke/LambdaForm$MH+0x0000000800e64400' (0x0000000800e64400)
> [6.289s][info][class,init ] 2755 Initializing
> 'java/lang/invoke/LambdaForm$MH+0x0000000800e64800' (0x0000000800e64800)
> [6.708s][info][class,nestmates ] LookupDefineClass:
> java/lang/invoke/LambdaForm$MH - non-nestmate, hidden, weak, with vm
> annotations
> [6.708s][info][class,nestmates ] LookupDefineClass:
> java/lang/invoke/LambdaForm$MH - non-nestmate, hidden, weak, with vm
> annotations
> [6.708s][info][class,load ]
> java.lang.invoke.LambdaForm$MH/0x0000000800e64c00 source:
> __JVM_LookupDefineClass__
> [6.708s][info][class,load ]
> java.lang.invoke.LambdaForm$MH/0x0000000800e65000 source:
> __JVM_LookupDefineClass__
> [6.708s][info][class,init ] 2756 Initializing
> 'java/lang/invoke/LambdaForm$MH+0x0000000800e64c00' (0x0000000800e64c00)
> [6.708s][info][class,init ] 2757 Initializing
> 'java/lang/invoke/LambdaForm$MH+0x0000000800e65000' (0x0000000800e65000)
> ... etc.{code}
> I have created a simple reproducer which demonstrates the issue.
> {code:java}
> // Run with
> // JAVA_OPTS="-Xlog:class*=info" groovy test.groovy # java11 or java17
> // JAVA_OPTS="-XX:+TraceClassLoading" groovy test.groovy # java8
> // Observe a steady stream of LambdaForm classes being loaded, forever.
> def foo(List<String> x) { }
> def bar(List<String> x) { foo(x) }
> List<String> l1 = new ArrayList();
> List<String> l2 = new LinkedList();
> while (true) {
> bar(l1)
> 127.times { bar(l2) }
> }{code}
> I'm using `Groovy Version: 4.0.13 JVM: 17.0.6-internal Vendor: Oracle
> Corporation OS: Linux`.
> I originally noticed this because the class churning caused a memory leak (at
> least partially caused by [
> [https://bugs.openjdk.org/browse/JDK-8313678]|https://bugs.openjdk.org/browse/JDK-8313678]),
> but generally this much churn is bound to have negative performance
> implications. In my real application this is churning about 10 million
> classes per day.
> I can avoid the issue when I spot it in my application by tweaking method
> arguments, but I'd be interested to know if this is a bug in Groovy and if it
> could
> be fixed or there are any other more robust mitigations I can use.
> I noticed https://issues.apache.org/jira/browse/GROOVY-8298 seems similar but
> not exactly the same, I think. The inline cache is not helping here, I'm not
> sure if that's perhaps because the receiver is stable and it's the arguments
> which change?
> I added logging to the sameClasses guard inserted in the invocation, and it's
> failing the guard because the argument types keep changing between LinkedList
> and ArrayList.
> I believe this is a performance issue, as well as the high churn being likely
> to highlight bugs or issues in the JVM and things like attached profiling
> agents.
>
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