[hibernate-dev] [infinispan-dev] Infinispan tx, config and multithreading

[Emmanuel Bernard]

Yes but Lukasz do see data disappearing (see initial email). So there  
is a problem somewhere?
Lukasz, can you maybe share the code and test with us so someone can  
have a closer look with you?

Emmanuel

On 13 août 09, at 18:56, Sanne Grinovero wrote:

> I am not an expert on this part of Lucene, but it looks like to me
> that the IndexWriter is the "driver/coordinator", and it's decisions
> are affected by a pluggable MergeScheduler; they do stuff on the
> internal buffers of the IndexWriter (dequeue the pending segments to
> be written to the index), but it shouldn't matter what they exactly do
> as the internal status of these classes are unaffected by our
> transactions.
> They take some decision about writing segments to the Directory and
> committing changes ("sync()") : as you implement this Directory you
> should only have to take care of this class, I don't think the
> MergeScheduler(s) are relevant: it just happens that the thread going
> to apply changes to the index might be a different one than the one
> pushing changes to the IndexWriter.
>
> In the Directory implementation you should use transactions to push
> state changes to the "underlying storage": as FSDirectory is playing
> with file descriptors and flushes, you do the same with Infinispan
> transactions.
>
> 2009/8/14 Łukasz Moreń <lukasz.moren at gmail.com>:
>> Yes, right, MergeSchedulers.
>>
>> 2009/8/14 Sanne Grinovero <sanne.grinovero at gmail.com>
>>>
>>> what are these "other" threads? Are you speaking about the
>>> MergeSchedulers?
>>>
>>> 2009/8/13 Łukasz Moreń <lukasz.moren at gmail.com>:
>>>> IndexWriter processes index update and delegates some job to other
>>>> threads and waits when they finish. These "other" threads works on
>>>> data modified
>>>> in IndexWriter transaction. So I think if I use transaction per
>>>> thread, "others" would not see data modified by IndexWriter until
>>>> commit.
>>>>
>>>> 2009/8/13, Emmanuel Bernard <emmanuel at hibernate.org>:
>>>>> Ah I thought it was using multiple threads because of your mass
>>>>> indexing. I did not know some threads were span specifically for  
>>>>> the
>>>>> Infinispan directory.
>>>>>
>>>>> On 13 août 09, at 17:34, Sanne Grinovero wrote:
>>>>>
>>>>>> Hi Łukasz,
>>>>>> what is your usage of these threads? did you consider using one
>>>>>> transaction per thread?
>>>>>>
>>>>>> Sanne
>>>>>>
>>>>>> 2009/8/13 Łukasz Moreń <lukasz.moren at gmail.com>:
>>>>>>> Newly created threads were not associated with any  
>>>>>>> transaction, so I
>>>>>>> suppose it was a problem. Sharing transaction between threads  
>>>>>>> seems
>>>>>>> to
>>>>>>> be a good solution.
>>>>>>> Thanks for help!
>>>>>>>
>>>>>>> 2009/8/13, Jason T. Greene <jason.greene at redhat.com>:
>>>>>>>> Correct. Also there could be read races as well, so if you are
>>>>>>>> going to
>>>>>>>> share a tx between threads, i would use some shared lock to
>>>>>>>> gaurantee
>>>>>>>> that only one thread can use it at a time. BTW this means you  
>>>>>>>> have
>>>>>>>> to
>>>>>>>> properly suspend/resume the TX via the TM API as well.
>>>>>>>>
>>>>>>>> Emmanuel Bernard wrote:
>>>>>>>>> Modifying a transaction means applying muations (like SQL  
>>>>>>>>> INSERT /
>>>>>>>>> UPDATE / DELETE) to the transactional resource?
>>>>>>>>>
>>>>>>>>> On 13 août 09, at 15:07, Jason T. Greene wrote:
>>>>>>>>>
>>>>>>>>>> When using transactions, the context is bound to the
>>>>>>>>>> transaction, and
>>>>>>>>>> you can move a transaction between threads. However, you  
>>>>>>>>>> should
>>>>>>>>>> only
>>>>>>>>>> be modifying a transaction with one thread at a time.
>>>>>>>>>>
>>>>>>>>>> Emmanuel Bernard wrote:
>>>>>>>>>>> Could it be that you are not using the same transaction  
>>>>>>>>>>> between
>>>>>>>>>>> different threads (ie you physically start different ones or
>>>>>>>>>>> different  "Infinispan contexts")?
>>>>>>>>>>> Infini guys, do you support transactional operation spanning
>>>>>>>>>>> several
>>>>>>>>>>> concurrent threads?
>>>>>>>>>>> On 13 août 09, at 14:04, Łukasz Moreń wrote:
>>>>>>>>>>>> I've tried with JBoss AS transaction manager and
>>>>>>>>>>>> JBossStandaloneTM.
>>>>>>>>>>>> The result is this same in all cases - error during merge.
>>>>>>>>>>>>
>>>>>>>>>>>> 2009/8/12, Emmanuel Bernard <emmanuel at hibernate.org>:
>>>>>>>>>>>>> Ok I understand better now.
>>>>>>>>>>>>> Do your tests in JBoss AS with it's decent transaction  
>>>>>>>>>>>>> manager
>>>>>>>>>>>>> (infinispan should have a config for it)
>>>>>>>>>>>>> For unit testing, force the indexing process in  
>>>>>>>>>>>>> hibernate to
>>>>>>>>>>>>> use a
>>>>>>>>>>>>> single thread (I ghnk it's possible ask Sanne of you don't
>>>>>>>>>>>>> know how).
>>>>>>>>>>>>>
>>>>>>>>>>>>> Exposing some configuration to infinispan makes sense.  
>>>>>>>>>>>>> can you
>>>>>>>>>>>>> start a
>>>>>>>>>>>>> thread explainig what is configurable and which one you  
>>>>>>>>>>>>> think
>>>>>>>>>>>>> we
>>>>>>>>>>>>> should expose to hsearch users. Ideally I would like to  
>>>>>>>>>>>>> offer
>>>>>>>>>>>>> one or
>>>>>>>>>>>>> two defaut config scenarios and allow to fallback to a  
>>>>>>>>>>>>> custom
>>>>>>>>>>>>> config.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Emmanuel
>>>>>>>>>>>>>
>>>>>>>>>>>>> On 12 août 2009, at 11:58, Łukasz Moreń
>>>>>>>>>>>>> <lukasz.moren at gmail.com>
>>>>>>>>>>>>> wrote:
>>>>>>>>>>>>>
>>>>>>>>>>>>>> Sorry, but my wifi does not work well today. I will try  
>>>>>>>>>>>>>> to
>>>>>>>>>>>>>> explain
>>>>>>>>>>>>>> it more clear.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> I'm using DummyTransactionManager available for  
>>>>>>>>>>>>>> Infinispan.
>>>>>>>>>>>>>> It associates transaction with the calling thread.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Steps to update index:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> 1. index writer acquires lock - begin of transaction
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> 2. if it is necessary, index writer delegates new  
>>>>>>>>>>>>>> threads to
>>>>>>>>>>>>>> do
>>>>>>>>>>>>>> merge work.
>>>>>>>>>>>>>> Those merge threads do not see changes made so far from
>>>>>>>>>>>>>> begin of
>>>>>>>>>>>>>> transaction,
>>>>>>>>>>>>>> and are looking for segments which are not yet in index.
>>>>>>>>>>>>>> Changes will be visible when AD.3 is completed.
>>>>>>>>>>>>>> For tests i tried to commit transaction when merge starts
>>>>>>>>>>>>>> and then
>>>>>>>>>>>>>> everything worked well. But then i need to start it  
>>>>>>>>>>>>>> again.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> 3. index writer releases lock - transaction is  
>>>>>>>>>>>>>> commited, all
>>>>>>>>>>>>>> changes
>>>>>>>>>>>>>> made in this transaction are visible for other threads.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Maybe using some other transaction manager could help?
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> What about Infinispan cache configuration? Some  
>>>>>>>>>>>>>> configuration
>>>>>>>>>>>>>> mechanism should be exposed to the user,
>>>>>>>>>>>>>> or we can hardcoded one in InfinispanDirectoryProvider is
>>>>>>>>>>>>>> enough?
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> 2009/8/12 Emmanuel Bernard <emmanuel at hibernate.org>
>>>>>>>>>>>>>> why?
>>>>>>>>>>>>>> Emmanuel Bernard
>>>>>>>>>>>>>> Pending
>>>>>>>>>>>>>> you there?
>>>>>>>>>>>>>> Emmanuel Bernard
>>>>>>>>>>>>>> Pending
>>>>>>>>>>>>>> Ok please describe in details what is going on. From what
>>>>>>>>>>>>>> you are
>>>>>>>>>>>>>> describing the tx cannot see all segments which looks  
>>>>>>>>>>>>>> like an
>>>>>>>>>>>>>> infinispan bug to me.
>>>>>>>>>>>>>> Pending
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> As a back up you can try wo transaction and see if that  
>>>>>>>>>>>>>> works
>>>>>>>>>>>>>> Emmanuel Bernard
>>>>>>>>>>>>>> Pending
>>>>>>>>>>>>>> technically the lucene index should cope with that
>>>>>>>>>>>>>> Emmanuel Bernard
>>>>>>>>>>>>>> 11:16
>>>>>>>>>>>>>> but I like this approach less
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Let's try and chat by email IF I'm not online, I need  
>>>>>>>>>>>>>> to run
>>>>>>>>>>>>>> on some
>>>>>>>>>>>>>> errands today.
>>>>>>>>>>>>>>
>>>>>>>>>>> _______________________________________________
>>>>>>>>>>> infinispan-dev mailing list
>>>>>>>>>>> infinispan-dev at lists.jboss.org
>>>>>>>>>>> https://lists.jboss.org/mailman/listinfo/infinispan-dev
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> --
>>>>>>>>>> Jason T. Greene
>>>>>>>>>> JBoss, a division of Red Hat
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> --
>>>>>>>> Jason T. Greene
>>>>>>>> JBoss, a division of Red Hat
>>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> infinispan-dev mailing list
>>>>>>> infinispan-dev at lists.jboss.org
>>>>>>> https://lists.jboss.org/mailman/listinfo/infinispan-dev
>>>>>>
>>>>>> _______________________________________________
>>>>>> hibernate-dev mailing list
>>>>>> hibernate-dev at lists.jboss.org
>>>>>> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>>>>>
>>>>>
>>>>
>>
>>