But with this version I've started getting
ConcurrentModificationExceptions again :(
Since a complete copy with add() is too slow, I guess if I need to
start locking the Model anyway? I was trying to avoid it.
On Mon, Oct 17, 2016 at 11:01 PM, Dave Reynolds
<dave.e.reyno...@gmail.com> wrote:
> Hi Martynas,
>
> On 17/10/16 21:51, Martynas Jusevičius wrote:
>>
>> Dave,
>>
>> I realized I mis-used "read-only" in b). I want to make changes, but
>> only in the throw-away per-request Model.
>>
>> I am currently testing such version:
>>
>> return ModelFactory.createOntologyModel(ontModelSpec,
>>
>> ModelFactory.createUnion(ModelFactory.createDefaultModel(),
>> ontModel.getBaseModel()));
>>
>> If, as I understand, it makes changes to the first Model only, which
>> is not stored anywhere then it might be what I need. Unless I'm
>> missing something?
>
>
> Yes, if you just want to be able add data and see the result but don't need
> any inference closure over it then a dynamic union is a good way to go.
>
> Dave
>
>
>> It returns a slightly different triple count, but so far I haven't
>> noticed any problems. And it runs way faster, in the order of
>> milliseconds.
>>
>>
>>
>> On Mon, Oct 17, 2016 at 10:43 PM, Dave Reynolds
>> <dave.e.reyno...@gmail.com> wrote:
>>>
>>> If you are using rules then they are likely to be a significant part of
>>> the
>>> overhead of accessing the cloned model.
>>>
>>> In which case it would make sense to materialize your OntModel as a
>>> no-inference OntModel and then copy that whenever you need to. That will
>>> mean that if you update your cloned copy you won't see additional
>>> inferences
>>> but given your mention of option (b) presumably you don't mean to change
>>> the
>>> data anyway.
>>>
>>> Dave
>>>
>>>
>>> On 17/10/16 20:36, Martynas Jusevičius wrote:
>>>>
>>>>
>>>> Hey,
>>>>
>>>> I am looking for a way to either
>>>> a) clone an OntModel in a performant way
>>>> b) make OntModel instance in OntDocumentManager read-only
>>>>
>>>> The use case goes like this: JAX-RS retrieves an OntModel instance
>>>> from OntModel manager per each request, adds to it or changes it, and
>>>> discards it after the request.
>>>>
>>>> We cannot directly change the OntModel instance in OntDocumentManager,
>>>> because that would pollute it with changes from each request and the
>>>> size would grow very quickly.
>>>>
>>>> So I went for the easy way out and cloned the OntModel on each
>>>> request, like this:
>>>>
>>>> OntModel ontModel =
>>>> OntDocumentManager.getInstance().getOntology(ontologyURI,
>>>> ontModelSpec);
>>>>
>>>> // lock and clone the model to avoid
>>>> ConcurrentModificationExceptions
>>>> ontModel.enterCriticalSection(Lock.READ);
>>>> try
>>>> {
>>>> Model baseModel =
>>>> ModelFactory.createDefaultModel().add(ontModel.getBaseModel());
>>>> OntModel clonedModel =
>>>> ModelFactory.createOntologyModel(ontModelSpec, baseModel);
>>>> if (log.isDebugEnabled()) log.debug("Sitemap model size:
>>>> {}", clonedModel.size());
>>>> return clonedModel;
>>>> }
>>>> finally
>>>> {
>>>> ontModel.leaveCriticalSection();
>>>> }
>>>>
>>>> That works, but the problem is that cloning using add() performs very
>>>> poorly. According to my profiling, this code takes almost a second to
>>>> execute with under 6000 statements, spent mostly in hasNext() of
>>>> various iterators.
>>>>
>>>> Not sure if it's relevant, but the OntModelSpec uses
>>>> GenericRuleReasoner.
>>>>
>>>> Is there a faster way or can you maybe suggest a different approach
>>>> altogether?
>>>>
>>>> Thanks.
>>>>
>>>>
>>>> Martynas
>>>>
>>>
>
