11 Replies Latest reply on Jul 27, 2004 5:09 PM by lafr

Throughput of data low while using CMP/CMR entitybeans Jbos

dev2gosoft Jul 20, 2004 4:54 PM

I am new to CMP .

Env:
JBoss 3.2.5
JDK 1.4.2
MSSqlServer 2000
Pentium 4 2.4 Ghz Hyperthreading
500 MB RAM

I have two EntityBeans OrderBean and LineItem Bean.

there are 23 order entities in the order table and about 6600 entities in the LineItem table. Both the tables are linked by a OrderID (Foreign key in LineItem table)

The Entity Beans are related by the primarykey OrderID .

When I am attempting to display a report with all the orders and their associated lineitems (6600) by using the cmr field in the order bean..The transaction times out after 5 minutes after generating about 5000 records...

More Details: findAllOrders retrieves a collection of local component interface Order and for each Order I call getLineItems (CMR field)

This is way too slow than i anticipated. Obviously the CMP tries to call ejbLoad for each bean and hence very slow.

The session facade api : that does all this has a transaction attribute of "required".

Obviously using a ejbSelect or ejbHome method would be more efficient
as we can altogether avoid linking the data with EntityBeans.

I would appreciate if someone can show how to optimize the CMP engine settings so that this can be done faster....I am using the default settings and i haven;t tried anything to fine tune the settings of CMP engine

Any help is appreciated.

1. Re: Throughput of data low while using CMP/CMR entitybeans

triathlon98 Jul 21, 2004 6:26 AM (in response to dev2gosoft)

Is your report generated inside a transaction?
It should be, otherwise there is no caching (actually worse, there probably is caching, but it is discarded all the time).

Joachim

P.S. Damned, I seem to be sounding like a broken record, telling the same story over and over...
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2. Re: Throughput of data low while using CMP/CMR entitybeans

dev2gosoft Jul 21, 2004 7:13 AM (in response to dev2gosoft)

Joachim,
Yes. All of this happens in a Session Facade api with a tx attribute of required.

Even the finder method to find the orders has a tx attribute of required.

Is this the typical throughput that we can expect ???

I am still puzzled that only 1000 records can be retrieved per minute if you are assoicating the data with CMP beans....the trace shows that ejbLoad is call for each bean..(record)...
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3. Re: Throughput of data low while using CMP/CMR entitybeans

triathlon98 Jul 21, 2004 10:08 AM (in response to dev2gosoft)

Ok.

Turn on CMP logging to see which SQL statements are being executed. Have a look at the docs about load-group, preloading etc. The configuration changes should be noticeable in the SQL statements executed.

Joachim
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4. Re: Throughput of data low while using CMP/CMR entitybeans

dev2gosoft Jul 21, 2004 10:47 AM (in response to dev2gosoft)

Thanks joachim,
how do i turn cmp logging>???

I turned on DEBUG messages in log4j.xml...i see the queries but also a deluge of message from all the other components

IS there a way to turn CMP Logging alone????
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5. Re: Throughput of data low while using CMP/CMR entitybeans

aloubyansky Jul 22, 2004 3:23 AM (in response to dev2gosoft)

In your case it would more efficient to use finder instead of CMR. Check out on-line docs Optimized Loading chapter. And lazy-resultset-loading on the wiki.
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6. Re: Throughput of data low while using CMP/CMR entitybeans

aloubyansky Jul 22, 2004 3:24 AM (in response to dev2gosoft)
Reposting XML in the code block
<category name="org.jboss.ejb.plugins.cmp"> <priority value="DEBUG"/> </category>
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7. Re: Throughput of data low while using CMP/CMR entitybeans

dev2gosoft Jul 22, 2004 8:11 AM (in response to dev2gosoft)

Alexey,
Thanks For your responses. I deeply appreciate it.
I need one small clarification or confirmation . The CMP query for generating related beans seems to be on each individual entity (i see ejbLoad being called for each entity). In a finder you specify the query to get all the entities and assoicate them with entity bean instances. hence using a finder will be more efficient

Is my understanding right???

Thanks in advance,
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8. Re: Throughput of data low while using CMP/CMR entitybeans

aloubyansky Jul 23, 2004 2:30 AM (in response to dev2gosoft)

ejbLoad will still be called on each instance because it's the spec. And this is not what causes performance problems.
You could also use read-ahead for CMR. But lazy-resultset-loading is not implemented for CMR.
In case of a finder, you just query the database and return results. In case of CMR, besides querying the database container will establish relationships. It's more expensive.
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9. Re: Throughput of data low while using CMP/CMR entitybeans

dev2gosoft Jul 23, 2004 7:36 AM (in response to dev2gosoft)
Alexey,
Thanks again for taking time out. It makes more sense to me now.
I used the finder and the performance improved relatively. 730 records in 12 seconds. I have not used Lazy-resultset-loading yet.

However sorry to pester you with couple of yet again follow up questions:

1. Do u know the xDoclet tag for generating lazy-resultset-loading in jboss deployment descriptors??? I could not find one in the docs (xdoc nor jboss).

2. This is an unexpected one. Initially I have put the finder method in the OrderBean instead of in LineItemBean . Interesting enough I was getting a class cast exception when i was type casting the object retrieved from the collection returned by the finder to a LineItemLocal object (see ejb-ql query) and I was getting a class cast exception. When I moved the finder to LineItemBean then it worked. Doesn't the spec say that the collection returned by a finder is determined by the SELECT OBJECT(Type) part of ejb-ql query???

/** @ejb.finder method-intf = "LocalHome" * description = "Find all line Items of a order " * query = "SELECT OBJECT(lineitem) FROM LineItemSchema AS lineitem WHERE fooditem.order.id=?1" * signature = "java.util.Collection findFoodItemsOfGroup(java.lang.String orderID)"

I apologize for pestering you. I would really appreciate if you can further clarify.

sincere thanks again,
-V
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10. Re: Throughput of data low while using CMP/CMR entitybeans

aloubyansky Jul 24, 2004 2:26 AM (in response to dev2gosoft)

I guess, there is no XDoclet tags for lazy-resultset-loading yet as it's a new feature. But I don't know for sure.

You can returned different entity types from ejbSelect methods but not finders.
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11. Re: Throughput of data low while using CMP/CMR entitybeans

lafr Jul 27, 2004 5:09 PM (in response to dev2gosoft)

I had some trouble a while ago when upgrading the jboss server.
This is my Order(afsta)/LineItem(afpos) example which works very well now:
/**
* @ejb.interface-method
* @ejb.relation
* name="Afsta-Afpos"
* role-name="1-afsta-n-afpos"
* multiple="yes"
* target-multiple="no"
* target-ejb="Afpos"
* target-role-name="n-afpos-1-afsta"
* @jboss.target-relation
* related-pk-field="afstaSerial"
* fk-column="afsta_serial"
* @jboss.relation-read-ahead strategy="on-find"
*/
public abstract java.util.Collection getAfpos();
/**
* @ejb.interface-method
*/
public abstract void setAfpos(java.util.Collection afpos);

I use XDoclet-1.2.1 for generating the DDs.
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