[hibernate-dev] hibernate and transaction using method annotation

[Bhuvan Gupta]

Got it

On Fri, Apr 29, 2016 at 11:46 AM, Vlad Mihalcea <mihalcea.vlad at gmail.com>
wrote:

> Hi,
>
> I answered your question on SO, but, next time, please use the forum (
> https://forum.hibernate.org/ )  or Twitter to send the SO question link.
> This mailing list is dedicated to discussions about developing Hibernate.
>
> Thanks,
> Vlad
>
> On Fri, Apr 29, 2016 at 7:10 AM, Bhuvan Gupta <bhuvangu at gmail.com> wrote:
>
>> Hello All,
>>
>> Link to question and discussion:
>>
>>
>> http://stackoverflow.com/questions/36920695/hibernate-and-transaction-using-method-annotation
>>
>> Below i have pasted whats in the link:
>>
>> Help/suggestion/advise/data points is really appreciated.
>>
>> Thanks in Advance:
>>
>> ------------------------------------------
>>
>> Firstly, I have given few data points.
>> Next will be the problem described.
>> ------------------------------
>>
>> *DATA POINTS:*
>> *[D1]* In Hibernate and Annotation and managed objects world, what i have
>> seen a common pattern like
>>
>> @Transactionalpublic void createStuff(..){// get entity manager and
>> call persist and other operatation}@Transactionalpublic SomeDtoObject
>> getStuff(..){// get entity manager and call find and getter to
>> polulate a object to return}
>>
>> In managed beans the Hibernate transaction is started and commited when we
>> call this methods.
>>
>> Hibernate doc says (link
>> <
>> https://docs.jboss.org/hibernate/orm/3.5/reference/en/html/transactions.html
>> >
>> ):
>>
>> The most common pattern in a multi-user client/server application is
>> session-per-request.
>>
>> *[D2]* Also it is advised that connection to database should be pooled
>> using connection pool library C3P0 as stated on postgres documentation
>> (link
>> <https://jdbc.postgresql.org/documentation/91/thread.html>):
>>
>> Pg will usually complete the same 10,000 transactions faster by doing them
>> 5, 10 or 20 at a time than by doing them 500 at a time.
>>
>> *[D3]* Also with JDBC
>>
>> *Given a single connection we can run one transaction at a time and as
>> many
>> statement as we like within that transaction.Its upto the
>> application(C3P0)
>> to make sure that two different thread executing two different
>> transactional method should not use same connection and one should wait
>> before calling the other method .*
>> ------------------------------
>>
>> *Problem:*
>> Now if we use the managed bean transaction pattern using annotation along
>> with a connection pool(*Let say only with 1 connection*) with hibernate
>> and
>> session-per-request
>> Also let say the code is something like
>>
>> @Transactionalpublic SomeDtoObject getStuff(..){// get entity manager
>> and call find and getter to polulate a object to returnSomeEntity se =
>> entityManager.find(someentity, primaryKey);//create Dtos// access
>> someEntity to all over this method to create SomeDtoObject that we
>> have to return.// also may access some file on system to fetch some
>> data is order to populate someDtoObject.// overall let say the method
>> take 150 milli second to do all its work}
>>
>> Now imagine there are two different thread(T1, T2) called for
>> getStuff(...)
>> T1 will enter the method and will acquire jdbc connection from connection
>> pool.
>> And when T2 will reach entityManager.find the C3P0 will check that there
>> is
>> no connection left it will put T2 on hold till T1 complete the execution
>> which will take around 150 milli second.
>>
>> Ideally, Given that getStuff(...) is going to do read only querys, both
>> thread can use same connection and dont hold thread from executing
>> queries.
>> In above case we are keep that connection idle and also keeping the thread
>> to wait.
>>
>> *MAIN QUESTION*
>> *Is there a way i can say to hibernate that a particular hibernate
>> transaction is readonly and hibernate can then reuse an already acquired
>> connection instead of asking for a new connection from the connection pool
>> ?*
>> ------------------------------
>>
>> *Few solution found/suggested:(not convincing)*
>>
>> 1
>> <
>> https://docs.jboss.org/hibernate/orm/3.5/reference/en/html/transactions.html
>> >
>> If
>> you are so much worried, dont use transaction using annotation, use
>> hibernate session yourself..... no i like that pattern :)
>> 2 <https://jdbc.postgresql.org/documentation/91/thread.html> Hibernate
>> provide a ConnectionReleaselink
>> <
>> https://docs.jboss.org/hibernate/orm/3.5/reference/en/html/transactions.html#transactions-connection-release
>> >
>> option
>> which can be set to after_statement.
>> *First* Hibernate C3P0 connection pool provider does not support
>> after_statement.
>> *Second* it will be a overhead just release and reacquire a connection.
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>
>