Spring JPA Multi Threading

Question

We are building a product, so from performance point of view I need some help. We are using complete Spring (MVC, JPA, Security etc..)

We have a requirement where say for a particular flow there can be 100 Business Rules getting executed at the same time. There can be n number of such flows and business rules.

These rules when executed actually fetch records from tables in database, these will contain few LAZILY INITIALIZED ENTITIES also.

I used Futures / Callables for multi threading purpose, but the problem is it fails to load LAZY variables. It gives Hibernate loading exception, probably some issue in TRANSACTIONAL not getting distributed in different threads.

Please let me know if there is any other way to approach?

Answer 1

if some Entity /Entity Collection is lazy fetched , and you are accessing it in another thread, you will face LazyInitialization exception, as lazy loaded entities can be accessed only within a transaction, and transaction wont span across, threads.

You can use DTO pattern, or if you are sharing an entity across threads, call its lazy initialized collections getter within the transaction so that they are fetched within transaction itself.

Answer 2

If you really need async processing then I suggest you use the Java EE specified way ie using JMS / MDB .

Anyways, since it seems like you want all the data to be loaded anyway for your processing. So Eager fetch all the required data and then submit the data for parallel processing. Or let each of the Tasks ( Callables ) fetch the data they require. Essentially, I am asking you to change your design so that the transactional boundaries doesn't cross multiple threads. Localize the boundaries within a single thread.