Perm or Metaspace OOME due to many duplicate JaxbAccessor classes

Solution Verified - Updated

Environment

  • JBoss Enterprise Application Platform (EAP)

Issue

  • We see a perm or metaspace OOME and the heap dump shows many duplicate JaxbAccessor classes (such as com.package.name.Class$$JaxbAccessorF_variablename) in our application classloader.

  • The OOME is hit in a call like the following:

    |- at java.lang.OutOfMemoryError.<init>()V (OutOfMemoryError.java:48)
|- at java.lang.ClassLoader.defineClass1(Ljava/lang/String;[BIILjava/security/ProtectionDomain;Ljava/lang/String;)Ljava/lang/Class; (Native Method)
|- at java.lang.ClassLoader.defineClass(Ljava/lang/String;[BIILjava/security/ProtectionDomain;)Ljava/lang/Class; (ClassLoader.java:760)
|- at java.lang.ClassLoader.defineClass(Ljava/lang/String;[BII)Ljava/lang/Class; (ClassLoader.java:642)
|- at sun.reflect.GeneratedMethodAccessor242.invoke(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object; (Unknown Source)
|- at sun.reflect.DelegatingMethodAccessorImpl.invoke(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object; (DelegatingMethodAccessorImpl.java:43)
|- at java.lang.reflect.Method.invoke(Ljava/lang/Object;[Ljava/lang/Object;)Ljava/lang/Object; (Method.java:497)
|- at com.sun.xml.bind.v2.runtime.reflect.opt.Injector.inject(Ljava/lang/String;[B)Ljava/lang/Class; (Injector.java:181)
|- at com.sun.xml.bind.v2.runtime.reflect.opt.Injector.inject(Ljava/lang/ClassLoader;Ljava/lang/String;[B)Ljava/lang/Class; (Injector.java:85)

  • Code similar to the following that performs a JAXB XML translation results in endlessly creating new classes:

    StringWriter sw = new StringWriter();
JAXBContext jaxbContext = JAXBContext.newInstance(myObject.getClass());
Marshaller marshal = jaxbContext.createMarshaller();
marshal.marshal(myObject, sw);

Resolution

To avoid this issue:

  • Upgrade to JAXB 2.1.13+

  • Set the -Dcom.sun.xml.bind.v2.bytecode.ClassTailor.noOptimize=true system property as a workaround

  • Cache the JAXBContext. For the best performance you should have just one instance of JAXBContext in your whole application. For example:

        class MyServlet extends HttpServlet {
        static final JAXBContext context = initContext();

        private static JAXBContext initContext() {
            return JAXBContext.newInstance(Foo.class,Bar.class);
        }
    }

    To unmarshall/marshall/validate a document, create a new Unmarshaller/Marshaller/Validator from the context as follows:

    public void doGet( HttpServletRequest req, HttpServletResponse ) {
    Unmarshaller u = context.createUnmarshaller();
    u.unmarshal(...);
}

    See Content from jaxb.java.net is not included.Unofficial JAXB Guide.

Root Cause

The following are causes of this issue:

Diagnostic Steps

Heap dump analysis:

  • Check for multiple instances of one of the following:
    • org.apache.cxf.common.jaxb.JAXBContextCache$2.
    • com.sun.xml.bind.v2.runtime.JAXBContextImpl

e.g. Running following OQL

select * from com.sun.xml.bind.v2.runtime.JAXBContextImpl

Class Name                                              | Shallow Heap | Retained Heap
---------------------------------------------------------------------------------------
com.sun.xml.bind.v2.runtime.JAXBContextImpl @ 0x9cc507a0|           96 |       280,904
com.sun.xml.bind.v2.runtime.JAXBContextImpl @ 0x9cb957b8|           96 |       396,288
com.sun.xml.bind.v2.runtime.JAXBContextImpl @ 0x9c1e9c70|           96 |     1,301,576
com.sun.xml.bind.v2.runtime.JAXBContextImpl @ 0x9bd52078|           96 |     1,730,776
com.sun.xml.bind.v2.runtime.JAXBContextImpl @ 0x9b8d8728|           96 |       956,240
com.sun.xml.bind.v2.runtime.JAXBContextImpl @ 0x9b4c2710|           96 |        47,680
com.sun.xml.bind.v2.runtime.JAXBContextImpl @ 0x9afd7958|           96 |       248,000
com.sun.xml.bind.v2.runtime.JAXBContextImpl @ 0x9aaac198|           96 |       264,024
com.sun.xml.bind.v2.runtime.JAXBContextImpl @ 0x9e62ca30|           96 |        74,472
com.sun.xml.bind.v2.runtime.JAXBContextImpl @ 0x9da0df98|           96 |       335,904
com.sun.xml.bind.v2.runtime.JAXBContextImpl @ 0x9d613f18|           96 |     1,301,760
com.sun.xml.bind.v2.runtime.JAXBContextImpl @ 0x9ceba6e8|           96 |     1,732,208
Total: 26 of 82 entries; 56 more                        |              |
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