premain: CGLIB error during the training run with Petclinic

[Sebastien Deleuze]

Hi,

I may have hit a premain bug using the latest
https://github.com/openjdk/leyden/tree/premain that triggers a CGLIB error
during the training run with Petclinic, and am looking for feedback.

The premain branch of
https://github.com/sdeleuze/petclinic-efficient-container currently
performs a training run of Petclinic where the application exits early
since -Dspring.context.exit=onRefresh is set, no workload is applied, the
application then starts again in the production and run faster as expected.
All good.

In the premain-training-run branch, I directly start Petclinic with
-XX:CacheDataStore=/tmp/application.cds in order to have the opportunity to
apply some workload to exercise the warm-up improvement capabilities later
in the production run.

On simple pages like http://localhost:8080/, it works as expected, but when
I try more complex pages like http://localhost:8080/owners, It get the
following error:

Request processing failed: java.lang.RuntimeException:
java.lang.IllegalStateException:
org.springframework.cglib.core.ReflectUtils$2: No compatible defineClass
mechanism detected: JVM should be started with
--add-opens=java.base/java.lang=ALL-UNNAMED for ClassLoader.defineClass to
be accessible. On the module path, you may not be able to define this
CGLIB-generated class at all.] with root cause
java.lang.reflect.InaccessibleObjectException: Unable to make protected
final java.lang.Class
java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain)
throws java.lang.ClassFormatError accessible: module java.base does not
"opens java.lang" to unnamed module @d5c1bc
at
java.base/java.lang.reflect.AccessibleObject.throwInaccessibleObjectException(AccessibleObject.java:388)
~[na:na]
at
java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:364)
~[na:na]
at
java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:312)
~[na:na]
at
java.base/java.lang.reflect.Method.checkCanSetAccessible(Method.java:190)
~[na:na]
at java.base/java.lang.reflect.Method.setAccessible(Method.java:184)
~[na:na]
at
org.springframework.cglib.core.ReflectUtils.defineClass(ReflectUtils.java:505)
~[spring-core-6.2.0-M7.jar:6.2.0-M7]

This application does not involve JPMS, it is just a regular Spring Boot
application. If I send more requests to the same endpoint, I see the
following error:

java.lang.VerifyError: Bad local variable type
Exception Details:
  Location:

org/springframework/samples/petclinic/owner/Owner_Accessor_82dqis.getProperty(Lorg/springframework/data/mapping/PersistentProperty;)Ljava/lang/Object;
@83: aload_2
  Reason:
    Type top (current frame, locals[2]) is not assignable to reference type
  Current Frame:
    bci: @83
    flags: { }
    locals: {
'org/springframework/samples/petclinic/owner/Owner_Accessor_82dqis',
'org/springframework/data/mapping/PersistentProperty' }
    stack: { 'java/lang/invoke/MethodHandle' }

To summarize, what I observe in my tests:
 - http://localhost:8080/owners without
-XX:CacheDataStore=/tmp/application.cds works
 - http://localhost:8080/owners with
-XX:CacheDataStore=/tmp/application.cds with an existing
/tmp/application.cds file works
 - http://localhost:8080/owners with
-XX:CacheDataStore=/tmp/application.cds with no existing
/tmp/application.cds file fails with the error mentioned above

Any thoughts?

Best regards,
Sébastien Deleuze

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