Question

even after creating new object of unmarshaller every time, threads are getting blocked
Please help

"http-80-3" daemon prio=10 tid=0x000000004fabe800 nid=0x7147 waiting for monitor entry [0x0000000042401000]
   java.lang.Thread.State: BLOCKED (on object monitor)
    at java.util.zip.ZipFile$ZipFileInputStream.read(ZipFile.java:457)
    - waiting to lock <0x00000000c02cce20> (a sun.net.www.protocol.jar.URLJarFile)
    at java.util.zip.ZipFile$ZipFileInputStream.read(ZipFile.java:475)
    at java.io.FilterInputStream.read(FilterInputStream.java:66)
    at java.io.DataInputStream.readInt(DataInputStream.java:371)
    at com.sun.xml.internal.bind.v2.bytecode.ClassTailor.tailor(ClassTailor.java:165)
    at com.sun.xml.internal.bind.v2.runtime.reflect.opt.AccessorInjector.tailor(AccessorInjector.java:108)
    at com.sun.xml.internal.bind.v2.runtime.reflect.opt.AccessorInjector.prepare(AccessorInjector.java:68)
    at com.sun.xml.internal.bind.v2.runtime.reflect.opt.OptimizedAccessorFactory.get(OptimizedAccessorFactory.java:156)
    at com.sun.xml.internal.bind.v2.runtime.reflect.Accessor$FieldReflection.optimize(Accessor.java:245)
    at com.sun.xml.internal.bind.v2.runtime.property.SingleElementNodeProperty.<init>(SingleElementNodeProperty.java:79)
    at sun.reflect.GeneratedConstructorAccessor21.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    at com.sun.xml.internal.bind.v2.runtime.property.PropertyFactory.create(PropertyFactory.java:113)
    at com.sun.xml.internal.bind.v2.runtime.ClassBeanInfoImpl.<init>(ClassBeanInfoImpl.java:145)
    at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.getOrCreate(JAXBContextImpl.java:479)
    at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl.<init>(JAXBContextImpl.java:305)
    at com.sun.xml.internal.bind.v2.runtime.JAXBContextImpl$JAXBContextBuilder.build(JAXBContextImpl.java:1100)
    at com.sun.xml.internal.bind.v2.ContextFactory.createContext(ContextFactory.java:143)
    at com.sun.xml.internal.bind.v2.ContextFactory.createContext(ContextFactory.java:110)
    at sun.reflect.GeneratedMethodAccessor47.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at javax.xml.bind.ContextFinder.newInstance(ContextFinder.java:202)
    at javax.xml.bind.ContextFinder.find(ContextFinder.java:376)
    at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:574)
    at javax.xml.bind.JAXBContext.newInstance(JAXBContext.java:522)

Answer 1

(Moving my comment to an answer)

Are you creating a JAXBContext every time? JAXBContext is thread safe and should be created once and reused. An Unmarshaller is not thread safe an a new one should be created per thread.

Now I am maintaining a map (ConcurrentHashMap
contexts ) wrapped by thread safe code to store all JAXBContexts(one
per type) as of now it is working nicely. Any other better suggestion
??

It depends on your application. You can also create one JAXBContext on many classes:

JAXBContext jc = JAXBContext.newInstance(A.class, B.class, C.class, D.class);

or

JAXBContext jc = JAXBContext.newInstance("com.foo:org.bar");