What will happened if two thread load the same object ?!!

Yashnoo · **Joined:** Wed Dec 17, 2003 4:24 am **Posts:** 188

Hi everyone:

There is a problem puzzled me all the time. We load an object from database in this way :

Code:

Trade trade=(Trade)session.load(Trade.class,trade_id);
trade.setName(....);
trade.setContent(...);
session.update(trade);

But I think there is a problem! If two thread load the same object and change it in the same time, what will happened?
Whether the data in database will be not identical? I mean that they will be not consistent. Or the database will be lock a long time when it in a long transaction.
I don't use Lock Modal because it is not need to do this everytime I load an object. Some one give me some idea? Help!

mota · **Joined:** Wed Nov 05, 2003 10:57 pm **Posts:** 96

If you don't use versionning, both threads change the object, and the last wins.

If you use versionning, the first thread wins, and the second get an exception.

mota

ernst_pluess · **Posted:** Thu Sep 02, 2004 2:38 am

This higly depends on the isolation level you are using. You might get an exception, have the second transactoin winning or the DB forces serialization of the transctions.

Get the Hibernate in Action book and read chapter 5.1.4 to learn the details.

HTH
Ernst