Re: [aspectj-dev] NotSerializableException: org.aspectj.runtime.reflect.

[Andy Clement <andrew.clement@xxxxxxxxx>]

I think all the fields mentioned that aren't basic strings are
populated 'on-demand' based on the string data  (or other factors that
don't need serializing).  That includes method/class fields and the
Cache field you mention - so making those transient is fine.

As John points out you will have incompatibilities between
weaved/unweaved if the fields are included in the serialized object.
Interestingly this is not a new problem, and I have no bugzillas
relating to it being an issue so I guess it really doesn't come up
very often.

If you want to rebuild the values for the fields, the target types
containing them should all have a method in like this:

private static void ajc$preClinit();

which you could invoke to do so.  But you'd have to ensure it gets
called just after deserialization.  I would need to check what else
ajc$preClinit() might do but I'm pretty sure it is just those tjp
values.

I can see arguments both ways: making tjp fields transient and calling
ajc$preClinit or making them serializable if it is tricky to get
ajc$preClinit called at the right time.  If compile time weaving it
doesn't seem as much of an issue for incompatibility between
weaved/unweaved form because the unweaved form is gone.  With ltw
maybe there is more chance of encountering the unwoven form again
sometime later.

Andy

On 2 March 2012 07:34, Choudary Kothapalli
<choudary.kothapalli@xxxxxxxxx> wrote:
>>>Would it be possible to have these fields set to transient but set them
>>> on-demand when deserialized (one time only) ?
>
> If you are talking about the following field, Andy may be the better person
> to answer. It looks possible to me and it  might be the cleanest solution to
> this problem.
>
>
> private static final org.aspectj.lang.JoinPoint.StaticPart ajc$tjp_0; /*
> synthetic field */
>
>>>Choudary, does your product require transparency in deserializing the
>>> instrumented objects (from an uninstrumented instance of the application)?
>
> At least my current problem involves using the same instrumented classes
> while serializing and deserializing. I didn't really think of the scenario
> of needing to deserialize using the uninstrumented classes, which might
> occur.
>
> So I think it would be a better idea to make the 'JoinPoint.StaticPart
> ajc$tjp_0;' fields transient and to set them on demand, if it's possible to
> do so.
>
> Thanks,
> Choudary.
>
>
> On Fri, Mar 2, 2012 at 9:58 AM, John Kew <jkew@xxxxxxxxxx> wrote:
>>
>> If I understand the use-case/problem correctly, there are not many great
>> solutions to this problem.
>>
>> Either we serialize StaticPart along with the object and make the
>> serialized class incompatible with an unweaved application, or we make it
>> transient and risk an inconsistent or unexpected state after the object is
>> rehydrated.
>>
>> Would it be possible to have these fields set to transient but set them
>> on-demand when deserialized (one time only) ? Choudary, does your product
>> require transparency in deserializing the instrumented objects (from an
>> uninstrumented instance of the application)?
>>
>> -John
>>
>> ________________________________
>> From: "Choudary Kothapalli" <choudary.kothapalli@xxxxxxxxx>
>> To: "AspectJ developer discussions" <aspectj-dev@xxxxxxxxxxx>
>> Sent: Friday, March 2, 2012 6:22:38 AM
>> Subject: Re: [aspectj-dev]
>> NotSerializableException:        org.aspectj.runtime.reflect.JoinPointImpl$StaticPartImpl
>>
>>
>> Hi Andy,
>>
>> I will try to give you the patch, but here is what I notice after taking a
>> deeper look into the JoinPointImpl.StaticPartImpl class.
>>
>> Not all fields in this class are primitives and Serializable classes. For
>> example, the Signature implementation classes like AdviceSignatureImpl have
>> Method as a field, which is not Serializable. But I think we can safely make
>> this a transient field.
>>
>> The same applies to Cache field in the SignatureImpl class. I think we can
>> make it transient too.
>>
>> Shall I go ahead and do these changes or do you have any reservations?
>>
>> Thanks,
>> Choudary.
>>
>> On Thu, Mar 1, 2012 at 11:05 AM, Andy Clement <andrew.clement@xxxxxxxxx>
>> wrote:
>>>
>>> Sure, and if you want to give me a patch that does it, even better :)
>>>
>>> cheers,
>>> Andy
>>>
>>> On 29 February 2012 16:52, Choudary Kothapalli
>>> <choudary.kothapalli@xxxxxxxxx> wrote:
>>> > Shall I raise a request to make JoinPoint.StaticPart serializable,
>>> > then? It
>>> > would solve the problem of serialization.
>>> >
>>> > Choudary.
>>> >
>>> >
>>> > On Wed, Feb 29, 2012 at 6:03 PM, Andy Clement
>>> > <andrew.clement@xxxxxxxxx>
>>> > wrote:
>>> >>
>>> >> Making them serializable is also reasonable.  There is nothing special
>>> >> in them - mostly strings/ints.
>>> >>
>>> >> There is no option to weave the classes with no synthetic fields.  It
>>> >> is feasible but they aren't necessarily cheap to construct and
>>> >> inlining their construction where they are used would damage
>>> >> performance to some degree.
>>> >>
>>> >> Andy
>>> >>
>>> >> On 29 February 2012 14:12, Choudary Kothapalli
>>> >> <choudary.kothapalli@xxxxxxxxx> wrote:
>>> >> > On second thoughts, making them transient may not be a good idea
>>> >> > because
>>> >> > the
>>> >> > deserialization may fail.
>>> >> >
>>> >> > Do you think you can make JoinPoint.StaticPart and its contents
>>> >> > Serializable? I am not sure if that would be correct, but just
>>> >> > asking.
>>> >> >
>>> >> > Or, is there any option to weave the classes so that the synthetic
>>> >> > fields do
>>> >> > not exist at all?
>>> >> >
>>> >> > I know that I'm asking for something that may not be a requirement
>>> >> > for
>>> >> > most
>>> >> > usage scenarios or the actual intended usage of AspectJ. But I am
>>> >> > stuck
>>> >> > with
>>> >> > this problem and just checking if there is a way out.
>>> >> >
>>> >> > Thanks for your time.
>>> >> >
>>> >> > Choudary.
>>> >> >
>>> >> >
>>> >> > On Wed, Feb 29, 2012 at 4:39 PM, Andy Clement
>>> >> > <andrew.clement@xxxxxxxxx>
>>> >> > wrote:
>>> >> >>
>>> >> >> I can provide you an option to make them transient, but I'm
>>> >> >> hesitant
>>> >> >> to just change the default to transient.  If you want an option
>>> >> >> like
>>> >> >> that, please open a bugzilla:
>>> >> >> https://bugs.eclipse.org/bugs/enter_bug.cgi?product=AspectJ
>>> >> >>
>>> >> >> and I'll take a look.
>>> >> >>
>>> >> >> cheers,
>>> >> >> Andy
>>> >> >>
>>> >> >> On 28 February 2012 14:35, Choudary Kothapalli
>>> >> >> <choudary.kothapalli@xxxxxxxxx> wrote:
>>> >> >> > My product MaintainJ uses AspectJ load time weaving to capture
>>> >> >> > the
>>> >> >> > call
>>> >> >> > trace at runtime. When weaving an application, the following
>>> >> >> > exception
>>> >> >> > is
>>> >> >> > seen.
>>> >> >> >
>>> >> >> > Caused by: java.io.NotSerializableException:
>>> >> >> > org.aspectj.runtime.reflect.JoinPointImpl$StaticPartImpl
>>> >> >> >     at java.io.ObjectOutputStream.writeObject0(Unknown Source)
>>> >> >> >     at java.io.ObjectOutputStream.writeObject(Unknown Source)
>>> >> >> >     at
>>> >> >> > xxx.yyyyy.ZZZClass.writeExternal_aroundBody4(ZZZClass.java:70)
>>> >> >> >
>>> >> >> > AspectJ LTW seems to insert many fields as below in the class
>>> >> >> > files
>>> >> >> > and
>>> >> >> > serializing them seems to be failing.
>>> >> >> >
>>> >> >> > private static final org.aspectj.lang.JoinPoint.StaticPart
>>> >> >> > ajc$tjp_0;
>>> >> >> > /*
>>> >> >> > synthetic field */
>>> >> >> >
>>> >> >> > Is there any quick fix for this? Can AspectJ make these fields
>>> >> >> > transient
>>> >> >> > without any other issues?
>>> >> >> >
>>> >> >> > Thanks,
>>> >> >> > Choudary Kothapalli
>>> >> >> > MaintainJ Inc.
>>> >> >> >
>>> >> >> > _______________________________________________
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>>> >> >> >
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>>> >> >
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