[infinispan-dev] distributed execution - invoking commands on self

[Galder Zamarreño]

On Apr 12, 2011, at 7:45 PM, Vladimir Blagojevic wrote:

> Yeah, it would be too strict to require Callable to be Cloneable so I 
> would opt out to serialization/deserialization as a clone method.
> 
> Galder, do out have a recommended mechanism for this in your marshalers?

Not really. I think you should marshall or clone it before executing operations against it.

For marshalling data, you just have to see what is done in the lazy deserialization code, just get hold of the VersionAwareMarshaller and marshall it.

> 
> Thanks Mircea
> 
> On 11-04-12 12:59 PM, Mircea Markus wrote:
>> can't you run the Callable locally on a clone of it? If Callable is Clonable then clone it in an orthodox manner, otherwise clone it by serializing/deseralizing it.
>> 
>> On 11 Apr 2011, at 19:58, Vladimir Blagojevic wrote:
>>> Sanne,
>>> 
>>> I thought about that as well but I do not see a way to ensure that all
>>> other commands have been sent to other nodes other than waiting for
>>> corresponding futures to return from get and then invoke locally in a
>>> serial fashion.
>>> 
>>> I do not see a hook anywhere that will tell me when a command has been
>>> dropped on the wire!
>>> 
>>> Vladimir
>>> 
>>> 
>>> On 11-04-11 2:21 PM, Sanne Grinovero wrote:
>>>> 2011/4/11 Vladimir Blagojevic<vblagoje at redhat.com>:
>>>>> Hi,
>>>>> 
>>>>> I discovered a problem with distributed framework in cases where
>>>>> Callables submitted for distributed execution contain mutable instance
>>>>> fields. Just before Callable is dispersed across cluster it gets invoked
>>>>> locally where instance fields of a submitted Callable can be possibly
>>>>> mutated; Callable is in turn sent to remote nodes with mutated values
>>>>> instead of "original" field values as submitted by user. For example,
>>>>> consider pi approximation example from wiki [1]. If CircleTest Callable
>>>>> declared insideCircleCount as an instance field instead of local field
>>>>> of call method we would ultimately get a wrong final result.
>>>>> 
>>>>> Therefore we need to ensure that each Infinispan node gets an unmodified
>>>>> instance of Callable for execution. I was looking at the possibility to
>>>>> send command to self thus causing creation of a marshaled copy of a
>>>>> Callable, pretty much like any other remote node receives it. However, I
>>>>> was unable to invoke a command on self. Any way to do this? How about
>>>>> invoking marshaling locally to create a Callable copy without going
>>>>> through rpc invocation layer? I though about skipping master/self node
>>>>> altogether but that's an easy way out;-)
>>>>> 
>>>>> Got suggestions, ideas?
>>>> Hi Vladimir,
>>>> I've no clue about invoking a marshalled command on self, but could
>>>> you not just make sure the local callable is being processed *after*
>>>> you have created a serialized copy (sent it to others) ?
>>>> 
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--
Galder Zamarreño
Sr. Software Engineer
Infinispan, JBoss Cache