What is the most elegant way to prevent working with the same hybris model in different threads?

Question

I am working with Hybris and stumbled over this problem a few times:

Imagine a situation in which multiple threads (maybe HTTP threads, maybe background threads) are reading/writing the same Database item (maybe in a clustered environment). How do I avoid concurrency issues? What are the options?

Try this post, it may have answers for your question : https://www.stackextend.com/hybris/control-concurrent-access-to-models-in-hybris/ — Mouad EL Fakir, Feb 21 '18 at 14:55

score 4 · Answer 1 · answered Feb 21 '18 at 13:11

4

Have a look at database locking:

Optimistic Locking: Every item contains a field version. On every update of the Item the version will be checked. You can only update the item if the version of the item you loaded before matches the version of the item in the database. On success the version will increase.
Pessimistic Locking: When a process intends to update an item it is locked so that no other process can change it until the process releases the lock

answered Feb 21 '18 at 13:11

Mehtrick

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How can I use these concepts in hybris? – Johannes von Zmuda Feb 21 '18 at 14:07
I don't know hybris. My answer adressed your original question which did not contain hybris. Sry – Mehtrick Feb 21 '18 at 14:56
Sorry, since this was the second answer that seemed not to be targeted to hybris, I realized I might have missed that information. – Johannes von Zmuda Feb 21 '18 at 15:07

Drexpp · Answer 2 · 2018-02-21T14:33:37.053

Well my first idea is that if you implemente a version value, in the global thread variable's environment, each time you access to that item you change its version value (for example it was 0001 you access and now it is 0002), so in that chase if your services are acting on the same item if the version that he is working (ex. version 0001) is not the same as the version in saved in the server (ex. version 0002).

I hope you could understand the idea.

score 0 · Answer 3 · answered Feb 21 '18 at 14:49

In this case, and using hybris ORM implementation that use a cache memory, I think that you can:

Server side : Adapte your business logic to support concurrency, and use cache eviction to get updated data.

Database side : Use database locking, but that might have a real performance issue in your system. For more about Database locking see this.

score -1 · Answer 4 · answered Feb 21 '18 at 13:06

-1

You can LOCK TABLEin SQL to prevent changes while a process makes INSERTS.

answered Feb 21 '18 at 13:06

Carlos López Marí

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In hybris you usually would not work with SQL statements, since hybris uses its own ORM which is called Jalo. – Johannes von Zmuda Feb 21 '18 at 13:08
@JohannesNolteHibernat ORM statements also usually include lock statements, such as Hibernate https://stackoverflow.com/questions/30323459/locking-a-table-with-hibernate – Carlos López Marí Feb 21 '18 at 13:10
hybris doesn't use hibernate as ORM implementation – homik Feb 21 '18 at 13:56

What is the most elegant way to prevent working with the same hybris model in different threads?

4 Answers4