There should be ONE instance of SQLMapClientImpl. And there's only ONE thing that creates it....a call to SqlMapClientBuilder.buildSqlMapClient();
Now the DAO framework builds that instance for you, but the DAOManagerBuilder works the same way...you get only one instance per call to buildDaoManager() (or whatever the method is called). I'm betting you have some service class or something that's madly instantiating or initializing DaoManagers or SqlMapClients .... or perhaps Spring containers....something is messed up wherever you configure your classes. Clinton On 3/8/07, Daniel Kalcevich <[EMAIL PROTECTED]> wrote:
Clinton, What do you mean? What would cause that type of condition in the SQL Maps? Daniel ________________________________ From: Clinton Begin [mailto:[EMAIL PROTECTED] Sent: Thu 3/8/2007 8:50 AM To: [email protected] Subject: Re: What is RequestScope used for? >> The snapshot I took showed 402 objects of the SqlMapClientImpl a It's now clear to me that you're building more than one SQL Map instance...possibly one per thread. It's not your transactional code, it's wherever you're building your DAOManager or your SqlMapClient. Clinton On 3/8/07, Daniel Kalcevich <[EMAIL PROTECTED]> wrote: 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:[EMAIL PROTECTED] ] Sent: Tue 3/6/2007 10:11 AM To: [email protected] 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: '[email protected]' 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: '[email protected] ' 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: ' [email protected]' 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: '[email protected] ' 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: '[email protected] ' 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
