hello,
I don't know how to solve concurrency problems in a nice way. To fix my updating code I set version control for entity and I check if get OptimisticLockException.
I think this is not the best solution, so I wish to know what is a beter solution for this classic case. I think I should get a record, lock it, update fields and unluck it ... but I don't know how to do it.
Thanks a lot for help
My code for update looks like this (strange enough for only one update):
while(true){
boolean ok = true;
Balance balance = testSessionA.getBalance(id,sleepTime);//sleep used just for testing
balance.setAmount(balance.getAmount()+10);
try{
testSessionA.update(balance);
}catch(javax.ejb.EJBException ex){
ex.printStackTrace();
if(ex.getMessage().equals("javax.persistence.OptimisticLockException")){
//how many times we should try to update??
ok = false;
}
}
if(ok){
break;
}
}
I have a stateless session bean,
@Stateless
@Remote(TestSessionA.class)
@Local(TestSessionA.class)
public class TestSessionABean implements TestSessionA{
public Balance getBalance(long bId, long sleepTime) throws Exception {
Balance b = em.find(Balance.class, bId);
Thread.sleep(sleepTime);//use sleep just to test
return b;
}
public void update(Balance balance) {
em.merge(balance);
}
and Balance entity have version controll:
@Entity
public class Balance implements Serializable{
@Version
@Column(name = "OPTLOCK")
public int getVersion() {
return version;
}
