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From "Daniel Kalcevich" <DKalcev...@marketlinx.com>
Subject RE: What is RequestScope used for?
Date Thu, 08 Mar 2007 16:21:55 GMT
OK, I went ahead and changed the places where DaoManager is used and made the logic something
like the following:
 
try {
     DAOManager.startTransaction();
 
     ...something...
 
    DAOManager.commitTransaction();
} finally {
   DAOManager.endTransaction();
}
 
After making those changes, I am still seeing those RequestScope objects in Memory.  The snapshot
I took showed 402 objects of the SqlMapClientImpl and 205, 824 objects of the Request Scope.
 
Is there any place else I should look to help with these RequestScope Objects?
 
Daniel

________________________________

From: Kalcevich, Daniel [mailto:dkalcevich@firstam.com]
Sent: Tue 3/6/2007 10:11 AM
To: user-java@ibatis.apache.org
Subject: RE: What is RequestScope used for?



Clinton,

 

Thanks for the help.  I will change the DaoManager to handle the transactions at the points
in the code where I am using them.  That way, should I perform any calls that require transactions,
they will already be there.  I'll try it out and let you know if I run into any more problems.
 

 

Daniel

 

________________________________

>> With regards to the DAO framework side of it, could I just wrap any calls to the
SQL maps 
>> with a try/finally that always calls the endTransaction() method on the SqlMapClient?
 

No, don't do that.  The iBATIS DAO framework is very similar to Spring.  It handles the transactions
inside the DAOs for you.  But the consumer of the DAOs shoudl be starting and ending transactions
on the DaoManager within a try/finally block.  

>> Because all of them are only SELECT statements, I don't really need transactions
inside the library itself.  
>> Or do I actually need to insert the startTransaction() and commitTransaction() methods
regardless?

No, you don't need start/commit/end if you're just doing selects.  You can just call the DAO
methods.  Just make sure you're not calling start without a corresponding end.... 

Clinton

________________________________

From: Kalcevich, Daniel 
Sent: Tuesday, March 06, 2007 9:46 AM
To: 'user-java@ibatis.apache.org'
Subject: RE: What is RequestScope used for?

 

Clinton,

 

Yes, the applications run inside the same JVM.

 

As for the Spring, I have already posted something to the Spring forum verifying that the
way in which we use them are correct, and they appear to be.

 

With regards to the DAO framework side of it, could I just wrap any calls to the SQL maps
with a try/finally that always calls the endTransaction() method on the SqlMapClient?  Because
all of them are only SELECT statements, I don't really need transactions inside the library
itself.  Or do I actually need to insert the startTransaction() and commitTransaction() methods
regardless?

 

Daniel

 

________________________________

Is this all in the same VM?

Spring is the recommended DAO solution and is probably the way that at least 50% of iBATIS
users use it.  You don't need to worry about transactions at all with Spring, it will take
care of it (as far as iBATIS is concerned at least).  Have a look at the spring docs to ensure
that you're using it the right way. 

I agree that you should start by looking at the other part that uses your own lib with iBATIS
DAO.  With iBATIS DAO you need to ensure you're starting and ending transactions in a try/finally
block just like with SqlMapClient. 

Cheers,
Clinton

 

________________________________

From: Kalcevich, Daniel 
Sent: Tuesday, March 06, 2007 9:29 AM
To: 'user-java@ibatis.apache.org'
Subject: RE: What is RequestScope used for?

 

Clinton,

 

Thanks for the response.  Now with regards to the Transactions... our application uses SQL
Maps in two different ways.

 

1.	Within Spring inside the Web App - We use transactions within Spring, thus SQL maps should
not be using the transactions.  
2.	A library we developed that the Web App uses - This uses the DAO framework and SQL Maps
internally, but only retrieves information from the DB, not inserts. 

 

For the Transactions, do I have to declare them explicitly in both places, or do you think
it would be better to address the standalone library first?

 

Daniel

 

________________________________

Yep, you have a leak and it is RequestScope related...but it's likely not an ibatis bug...

It's more likely that you're not ending transactions properly.

try {
  sqlMapClient.startTransaction(); 
  ///... do work
} finally {
  sqlMapClient.endTransaction();
}

Clinton

 

________________________________

From: Kalcevich, Daniel 
Sent: Tuesday, March 06, 2007 8:18 AM
To: 'user-java@ibatis.apache.org'
Subject: RE: What is RequestScope used for?

 

OK, upon looking at the Yourkit, I am showing the number of objects in memory as the following:

 

-          com.ibatis.sqlmap.engine.impl.SqlMapClientImpl - 212 objects with a total retained
size in memory of 31.38MB

-          com.ibatis.sqlmap.engine.scope.RequestScope - 108, 544 objects with a total retained
size in memory of 16.49MB.

-          com.ibatis.sqlmap.engine.scope.SessionScope - 27,136 objects with a total retained
size in memory of 3.03 MB.

 

Do those numbers make sense?  I only question it because with every snapshot of the memory
I have taken along the way, the RequestScope/SessionScope objects keep increasing.

 

Daniel

 

________________________________

From: Kalcevich, Daniel 
Sent: Tuesday, March 06, 2007 7:04 AM
To: 'user-java@ibatis.apache.org'
Subject: RE: What is RequestScope used for?

 

I found about this RequestScope through the profiler YourKit.  Here is the trail that references
the IBatis objects.

 

map of com.ibatis.sqlmap.engine.scope.RequestScope 

--[121] of java.lang.Object[513] 

---elementData of java.util.ArrayList 

----list of java.util.Collections$SynchronizedRandomAccessList 

-----pool of com.ibatis.common.util.ThrottledPool 

------requestPool of com.ibatis.sqlmap.engine.impl.SqlMapExecutorDelega te 

------delegate of com.ibatis.sqlmap.engine.impl.SqlMapClientImpl 

-------client of com.ibatis.dao.engine.transaction.sqlmap.SqlMapDao TransactionManager 

--------transactionManager of com.ibatis.dao.engine.impl.DaoContext 

---------[0] of java.lang.Object[11] 

----------elementData of java.util.ArrayList 

-----------value of java.lang.ThreadLocal$ThreadLocalMap$Entry 

------------[1442] of java.lang.ThreadLocal$ThreadLocalMap$Entry[2049] 

-------------table of java.lang.ThreadLocal$ThreadLocalMap 

--------------threadLocals of java.lang.Thread [Stack Local, Thread]

 

 

The reason I thought it might be contributing to a memory leak was the fact that at every
snapshot I take, the number of HashMaps continues to increase without going down.  Then when
I look at what it is referring to, it points to the RequestScope.

 

While looking in the trace, I saw that it was referencing the DaoContext's transaction Manager.
 Could the Transaction Manager be playing a part in this?  My application uses Spring with
SQL Maps, but a library we wrote uses the DAO Framework specifically.  The Spring application
does not use it.  I think that is worth looking into, given what I see in the profiler.

 

Daniel

 

 

________________________________

From: Kalcevich, Daniel 
Sent: Monday, March 05, 2007 11:37 AM
To: 'user-java@ibatis.apache.org'
Subject: What is RequestScope used for?

 

Hello,

 

I have a Spring, Struts, SQL Map application that runs on JBoss/Tomcat.  And while going through
a profiler, I am seeing that there are several instances of "com.ibatis.sqlmap.engine.scope.RequestScope".
 What is that object used for?  The reason I ask is that I am trying to track down a memory
leak and am wondering if this class is possibly part of the cause?  Any help is greatly appreciated.
 Thank you.

 

Daniel


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