[hibernate-dev] hibernate and transaction using method annotation

[Vlad Mihalcea]

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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