RFR: JDK-8068721 - RMI-IIOP communication fails when ConcurrentHashMap is passed to remote method

[Chris Hegarty]

On 27/03/15 19:24, Mark Sheppard wrote:
> Hi
>      based on feedback webrev has been updated as follows:
>
> http://cr.openjdk.java.net/~msheppar/8068721/jdk9/corba/webrev.01/

The changes in the corba repo look good to me Mark.

-Chris.

> http://cr.openjdk.java.net/~msheppar/8068721/jdk9/jdk/webrev.01/
>
> regards
> Mark
>
> On 23/03/2015 21:25, Mark Sheppard wrote:
>> Hi
>>  please oblige and review the following fix
>>
>> http://cr.openjdk.java.net/~msheppar/8068721/jdk9/corba/webrev/
>> http://cr.openjdk.java.net/~msheppar/8068721/jdk9/jdk/webrev/
>>
>>
>> which addresses the issue in
>> https://bugs.openjdk.java.net/browse/JDK-8068721
>>
>> This relates to RMI-IIOP and the interplay between custom marshalling
>> of ValueTypes and
>> the corresponding serialization of a Java class, in this case
>> ConcurrentHashMap.
>>
>> ConcurrentHashMap changed its structure in jdk8 from that used in jdk7.
>> This resulted in modification to the readObject and writeObject methods,
>> and in particular, former serial fields were removed, resulting in
>> writeObject using PutField and readObject using defaultReadObject.
>> The writeObject invokes the putFields method of an ObjectOutputStream
>> multiple times, and assumes
>> that it will receive the same PutField object instance for each
>> invocation. The spec
>> doesn't endorse this behaviour - but that's what the implementation of
>> ObjectOutputStream
>> provides. However in the case of RMI-IIOP, the OutputStreamHook, a
>> subclass of ObjectOutputStream, returns a new instance for each
>> putFields invocation. Thus, the ConcurrentHashMap writeObject results
>> in improper serialization in the context
>> of RMI-IIOP.
>> In the unmarshalling flow of ConcurrentHashMap, the readObject now
>> uses defaultReadObject rather than GetField
>> In this call flow the IIOPInputStream attempts to ignore any primitive
>> field, in the serialized data, that doesn't
>> correspond with a reflective field of the object. However, it leaves
>> the primitive in the stream.
>> Thus, in the case of ConcurrentHashMap, which has serialized two
>> integers and
>> an array of Segments (subclass of ReentrantLock), this results in
>> erroneous
>> deserialization, with a misinterpretation of a value tag in the stream
>> as an array length
>> and an attempt to allocate a very large array ensues, with an
>> exception being thrown.
>>
>> The OutputStreamHook now returns the same instance of PutField
>> allocated for each separate call of putFields method.
>> This highlights a need to tighten up and disambiguate the
>> OutputObjectStream spec for putFields.
>>
>> IIOPInputStream now removes the primitive values from the stream.
>>
>> regards
>> Mark
>