How to monitor Toplink cache ?

not just printIdentityMap();
I want to know about over all size of cache
and keep record in some log file
can i do this ?
Regards ,
Kowit Laison

Check the class RuntimeServices in the Javadoc...
- Don

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How to Add Index in Toplink Cache

Hi
We are using toplink as ORM.we are using default cache option (soft cache weak identity)provided by toplink, need to optimize the object retrival from cache, is there any option to create Index ( like database index) on the toplink cache.
Message was edited by:
[email protected]

The TopLink cache is indexed by primary key only. It does not support additional indexes.
Doug

How do I sync Toplink Cache with my Database?

Hey guys,
We are running macro's through an excel sheet that connects to the database and performs Updates and Inserts.
Since this database update is NOT taking place through TopLink (in a Unit of Work) - we do not see the database changes through the web app on the front end unless we bounce our webserver. Presumably the Toplink cache is re-built on start up...so then we can see the changes.
My question is, what can I do to make sure the TopLink cache is aware of the database changes we have made through the macro without having to bounce the server? Is there a re-fresh or sync command that can be run?
This task is sort of a one time thing, so I don't want a solution that involves the cache going to sync itself on a schedule or anything like that. Maybe bouncing is the best solution?
Thoughts?
We are using Toplink 9.0.4
Thanks.

Hello,
Because it is a one time thing, if you can make sure no other TopLink process are going on, you can probably get away with initializeAllIdentityMaps() or the intitializeIdentityMap(Class) methods on the session. These will clear the identity maps, having the obvious draw back of removing all object identity which will cause problems with running processes though. It might be better than bouncing the server - it depends on the application. Logging out of the session and logging back in has the same effect of clearing the cache, but with a bit more overhead. Benifit is that running processes will get errors if they continue to use the session, rather than strange behaviior if they continue to use objects after identity is lost.
Another alternative is to run refresh queries on the data you know might be in the cache or that might have been affected. Drawbacks are that this brings them into the cache if they are not already there.
TopLink 9.0.4 is a quire a few versions back, and in newer versions there is cache invalidation. An object marked as invalid is not removed, so object identity is maintained, but on the next query the data will be refreshed - ensuring subsequent queries will get results from the database without having to be told explicietly to refresh or being set to always refresh. Invalidation can be triggered on particular objects, classes or the entire cache or different policies can be set to set a time to live etc.
Except for bouncing the server or logging out of the session, all of the above leave some possibility that a concurrent user will still have a reference to stale data and continue to use it after the process has run on the database. So I hope you use optimistic locking and that your batch process updates the version to avoid other process from overwriting with stale data.
Best Regards,
Chris

How to monitor page hit rates?

I see a lot of references in docs and white papers to cache hit rates for the Parallel Page Engine, but I've not found any documentation on how to monitor this system-wide (only how to turn on portlet statistics and get a manual page-by-page look at cache success/failure).
Is there any way to determine the cache hit rate for the PPE?

Stephen,
I'm sorry you seem to be experiencing some problems with the support and documentation of the portal software.
The link above was posted on May 1st 2002, and was posted as an absolute link rather than a dynamic product link. As the document name is revved the link will change, hence why an old link from the forums will no longer work.
The document you seek is here. I assume that by referring to webcache you mean that when you add the XLF logging format options webcache complains about x-ecid (for example). This indicates that you have not applied the core iAS patchset which is required to allow webcache to understand these extended log parameters. I believe that the document refers to this as a requirement to get 'full functionality' - perhaps that is a little esoteric, I'll change it in the next rev.
If you continue to be unsuccessful in deploying this note please let me know what errors you're seeing and I'll see what I can do. I'm working on an end-to-end performance kit at the moment that will supercede this document so I'll take your comments on board when revving this area.
Regards
Jason Pepper
Principal Product Manager
Oracle9iAS Portal

Querying the toplink cache under high-load

We've had some interesting experiences with "querying" the TopLink Cache lately.
It was recently discovered that our "read a single object" method was incorrectly
setting query.checkCacheThenDB() for all ReadObjectQueries. This was brought to light
when we upgraded our production servers from 4 cores to 8. We immediatly started
experiencing very long response times under load.
We traced this down to the following stack: (TopLink version 10.1.3.1.0)
at java.lang.Object.wait(Native Method)
- waiting on <0x00002aab08fd26d8> (a oracle.toplink.internal.helper.ConcurrencyManager)
at java.lang.Object.wait(Object.java:474)
at oracle.toplink.internal.helper.ConcurrencyManager.acquireReadLock(ConcurrencyManager.java:179)
- locked <0x00002aab08fd26d8> (a oracle.toplink.internal.helper.ConcurrencyManager)
at oracle.toplink.internal.helper.ConcurrencyManager.checkReadLock(ConcurrencyManager.java:167)
at oracle.toplink.internal.identitymaps.CacheKey.checkReadLock(CacheKey.java:122)
at oracle.toplink.internal.identitymaps.IdentityMapKeyEnumeration.nextElement(IdentityMapKeyEnumeration.java:31)
at oracle.toplink.internal.identitymaps.IdentityMapManager.getFromIdentityMap(IdentityMapManager.java:530)
at oracle.toplink.internal.queryframework.ExpressionQueryMechanism.checkCacheForObject(ExpressionQueryMechanism.java:412)
at oracle.toplink.queryframework.ReadObjectQuery.checkEarlyReturnImpl(ReadObjectQuery.java:223)
at oracle.toplink.queryframework.ObjectLevelReadQuery.checkEarlyReturn(ObjectLevelReadQuery.java:504)
at oracle.toplink.queryframework.DatabaseQuery.execute(DatabaseQuery.java:564)
at oracle.toplink.queryframework.ObjectLevelReadQuery.execute(ObjectLevelReadQuery.java:779)
at oracle.toplink.queryframework.ReadObjectQuery.execute(ReadObjectQuery.java:388)
We moved the query back to the default, query.checkByPrimaryKey() and this issue went away.
The bottleneck seemed to stem from the read lock on the CacheKey from IdenityMapKeyEnumeration
public Object nextElement() {
if (this.nextKey == null) {
throw new NoSuchElementException("IdentityMapKeyEnumeration nextElement");
// CR#... Must check the read lock to avoid
// returning half built objects.
this.nextKey.checkReadLock();
return this.nextKey;
We had many threads that were having contention while searching the cache for a particular query.
From the stack we know that the contention was limited to one class. We've since refactored that code
not to use a query in that code path.
Question:
Armed with this better knowledge of how TopLink queries the cache, we do have a few objects that we
frequently read by something other than the primary key. A natural key, but not the oid.
We have some other caching mechanisms in place (JBoss TreeCache) to help eliminate queries to the DB
for these objects. But the TreeCache also tries to acquire a read lock when accessing the cache.
Presumably a read lock over the network to the cluster.
Is there anything that can be done about the read lock on CacheKey when querying the cache in a high load
situation?

CheckCacheThenDatabase will check the entire cache for a match using a linear search. This can be efficient if the cache is very large. Typically it is more efficient to access the database if your cache is large and the field you are querying in the database is indexed in the table.
The cache concurrency was greatly improved in TopLink 11g/EclipseLink, so you may wish to try it out.
Supporting indexes in the TopLink/EclipseLink cache is something desirable (feel free to log the enhancement request on EclipseLink). You can simulate this to some degree using a named query and a query cache.
-- James : http://www.eclipselink.org

Refresh toplink cache from tirgger

How to update the toplink cache due to change in the database by some external process or procedure?
This question was posted some time back and one of the suggestion was to create a trigger on the table holding the data and implement callout to the toplink cache to refresh. I will appreciate if any one can let me know where I can I find more information to implement such a callout method from trigger on the database table.
We are accessing the toplink objects from OC4J container from where a singleton is managing the calls to the toplink objects. We already have methods in place to refresh the cached object based on timeouts but now the new requirements are to refresh the objects only if the data is changed in the database.
Thanks
Ahmad

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Thank's

Toplink Caching issue

I have three Entities say C1 , P1 and card. Relation between these
entities are like this
P1 to Card ( one - one mapping )
C1 to Card ( one - many mapping )
I have three usecases. Usecase 1 uses the mail Entity C1. It will
create one record using C1. ( keep in mind that there will not be any data for entity card at that time ).
Second usecase , Usecase 2 , uses Entity P1 and creates data in P1 as
well as Card.
Third usecase will again take C1 and try to get the card data which
were inserted through P1.
But unfortunately , it is coming as null ... But if I restart the server and access the third usecase then I'm getting all the card data from C1 Entity which were saved through P1 Entity .
To summarise my finding , issue is with Toplink caching. When i
accessed the first usecase, C1 is cached. In the second usecase , I updated Entity card using P1. When i accessed the third usecase , toplink is returing the cached entity. Toplink is not able to identify whether related entity got changed or not....
Workaround is not to use cache for C1 entity. It is working but it will
not be the correct solution.
any one faced this issue in Toplink ?
Correct me if my findings are not correct...

Hello,
Its not that the cache isn't working, its that you are updating relationships in the database but not in the cache. Take the case of a 1:M from B->C used in a previous response. It looks like the foreign key used in this relationship (in the C table) is mapped to the C object either as a direct to field mapping, or through a 1:1 to the A object. When you change this so that it now somehow points to the B object, you haven't updated the B object to include the C in its collection. Because B has a 1:M mapping collection of Cs, when you next get that B object from the cache, its collection will not contain the newly referenced C (assuming indirection is not used or has been previously triggered). This is a result of you mapping the 1:M in the first place - since it is storing the collection in the object.
If you are going to make changes that affect relationships and yet not update the relationships directly I would suggest either:
A) refreshing affected objects from the database when done. In this case, refreshing the B object will result in TopLink requerying the B->C relation and picking up any changes (depending on your refresh options on the B descriptor though - please check the docs if you need more info).
B) Not mapping these relationships. Instead, when you need to find C objects referenced from B, query for them.
Both options are less efficient as they cause more hits to the database. This is why it would be preferred if you updated the relationships when you change fields that affect those relationships, but it is up to you to decide which will work best for your application.
Please note that the cache is working, in fact the situation you are seeing is due to it working. I am not sure of how your situation would work with DAO as you mentioned in a previous post, but it sounds like it would always hit the database. This situation is a result of you making changes in the database but not changing the object model to reflect those changes, proving that the cache is indeed working. While you mention that some objects are not in your use case, they are in the database but just not mapped in TopLink. In the case of a 1:M mapping, the database shows a 1:1 back relationship that you have not mapped in your object model. So this would be more a case of your object model not matching your database model, and not being taken into account in your use cases.
Best Regards,
Chris

Database Change Notification and TopLink Cache Invalidation

Has someone succeeed in implementing the How-to Database Change Notification and TopLink Cache Invalidation.
I have corrected some document errata about the pl/sql content and I manage to have messages in the 'notify_queue'.
I obtain the Topic in Java from this queue.
But the TopicSuscriber instances do not receive any message. Is there something to have in mind to make it work ?
Regards.

Reviving this thread again...
I am using DCN feature to build a middle-tier cache. I know oracle has problem sending physical rowid in case of 'Index Organized Table', however, in normal table also its not able to send proper rowid.
e.g, I have 2 records in Table A with rowid AAARIUAAGAAAV/uABw and AAARIUAAGAAAV/pAAX.
I have updated both the records. Strangely for the first record, oracle is sending INVALID rowid, although for the second record its sending the valid one.
Following is the output:
Row 1: (Wrong rowid being sent, AAARIUAAGAAAV/uABw is replaced with AAARIUAAGAAAXDCAAr)
Connection information : local=localhost.localdomain/127.0.0.1:47633, remote=localhost.localdomain/127.0.0.1:2278
Registration ID         : 2102
Notification version    : 1
Event type              : OBJCHANGE
Database name           : <sid>
Table Change Description (length=1)
    operation=[UPDATE], tableName=<table_name>, objectNumber=70164
    Row Change Description (length=1):
      ROW: operation=UPDATE, ROWID=AAARIUAAGAAAXDCAAr
Row 2: (Right rowid being sent, AAARIUAAGAAAV/pAAX)
Connection information : local=localhost.localdomain/127.0.0.1:47633, remote=localhost.localdomain/127.0.0.1:2278
Registration ID         : 2102
Notification version    : 1
Event type              : OBJCHANGE
Database name           : <sid>
Table Change Description (length=1)
    operation=[UPDATE], tableName=<table_name>, objectNumber=70164
    Row Change Description (length=1):
      ROW: operation=UPDATE, ROWID=AAARIUAAGAAAV/pAAX
Any idea ?

ValueHolder Indirection and TopLink Cache

We have a parent object A (main table) and child object B (a lookup table), mapped thought ValueHolder Indirection.
We use ReadAllQuery to build SQL and retrieve object A(s), and associated B(s).
The query result is used to populate a web page table.
The problem is that when the table is populated, the exact same lookup query against object B is repeated without checking cache. That data field is populated by object_A.object_b.description. For example, below same query would be repeated many times when loading up the web page table:
Select description_id, description from Table_B where description_id = 1
Why the query generated by this Indirection not checking cache? Anyway to force it to check TopLink cache first before querying against database?
Thanks for any help!
Jeffrey

Thanks for the reply.
We use JDeveloper 10.1.3.2. TopLink map in JDev is used to map all table objects and their relationships. So In TopLink map, object(table) A has a ValueHolder object(table) B through indirection. The primary key of B is: description_id, which is used in the table reference mapping.
We use the default TopLink settings in JDev, so object B has below settings in TopLink map:
Identity Map: FullIdentityMap
Size: 50 (there are only about 20 records in this lookup table)
Existence Checking: Check Cache
We don't have any other caching mechanism other than TopLink's. EJB 3.0 is used as service bean, and External Transaction Controller (OC4J) is used.
How to check if B is already in the TopLink cache? I heard ReadAllQuery always goes to database w/o checking TopLink cache, but in the case, the query generated by lazy loading indirection is after the ReadAllQuery execution (when the web page table is loading up).
Jeffrey

Keeping the toplink cache insync across a cluster

We would like to deploy our application across a cluster of 10g application servers and we are using toplink as our persistence framework using POJO's. I have been looking around and I have been unable to find anything very helpful on how to setup toplink to be able to keep the cache in sync across the cluster. Has anyone does this on 10g with POJO's? If so can you please point me to an example or a good piece of documentation?
Thanks
Marc

The documentation on Cache synch can be found starting on page 8-3 on the 10g (9.0.4) release.

Querying TopLink Cache

My system demands caching the result sets obtained from a ReadAllQuery. I might make several queries on this static set of cached data. But the data to be cached is small. I use TopLink's use session.getProject().FullIdentityMap() to cache the output of ReadAllQuery that i execute at the start of the system.
But am not able to query the cache from an external API later ( which could be several minutes later). How can i manipulate the TopLink cache APIs to get this done. Kindly Reply.

Hi Manoj,
If I understand you correctly, you persist some objects and then later query them. You don't get the results you expect when you use checkCacheOnly(). You need to use checkCacheThenDatabase() and when you do this you're seeing SQL I expect.
If your cache type for the class is FullIdentityMap then TopLink will never release objects of that class once read and your checkCacheOnly() query should work.
I'm guessing that you're using a different TopLink session. You mention you have a number of services. What environment are you running in and what is your architecture (e.g., servlet or EJB)? Statics don't solve sharing problems especially in an application server or web application environment in which multiple classloaders are employed.
--Shaun

Toplink cache coordination

I'm just getting started on setting up clustered Toplink caches.
I'm attracted to the JMS option because setting up message brokers on our system also opens up a number of other possibilities, in particular ensuring caches are invalidated following batch updates, arranging for Swing programs to update their displayed data and so on.
I'd like to hear some experience from people using various message brokers for Toplink cache coordination. Particularly with Toplink web apps under Oracle application server.
And incidentally, anyone know how to configure cache coordination for old ADF applications where the Toplink stuff is rather well hidden?

I raised a TAR with Oracle. The short answer is that you can't do cache coordination either with ADF business objects, or with Toplink Essentials (as opposed to Oracle Toplink, which doesn't yet support JPA).

Toplink Cache not refreshed

In my project, TOPLINK is used. To carry out the CRUD operation, Stored procedures are used on all objectcs.
Toplink query is not used.
In some cases, since we wanted to use the existing Stored procedures for running the business logic, toplink is not used.
After running these procedures, we refresh the Toplink Cache by using "refreshObject(java.lang.Object p1)" method of UnitOfWork before we read the Object.
When we read this object, the data appears to be in sinc with what is present in the database tables.
But when we write the data once again to the database, Toplink some how refers to the Old data ( Data which was present before refreshing).
It seems to be a strange issue.
Kindly help.

If you call refresh on an object already loaded in the UnitOfWork, and the object was modified before you call refresh, the refresh will override the modification done to the object.
You should never need to call refresh.
What you should do instead of refresh is to invalidate on session cache so when ever you read the object later, it will be refresh if was invalidated, so more efficient.
If you use TopLink 11 JPA api you need to flush to get current transaction/uow see the modified data in db.
But realistically, stored procedure do not work well with O-R framework, and you say Toplink query is not used, why not removing TopLink from the equation? If you want better JDBC you can use iBatis or Spring.

Toplink Cache problem

I am using JDev of following version "Studio Edition Version 10.1.3.1.0.3984
Build JDEVADF_10.1.3.0_NT_061009.1404.3984".
I had an application with JSF and Toplink and am facing issues with toplink cache mechanism while TESTING IN JDEV . Following is the scenario.
1) When clicking on a link, say 'Get status' , i am querying data from database and displaying in JSF.
2) Later, i am updating particular record.
3) when i click on the link again (Get status), updated data is not gettng reflected.
Here is the code to get data and i am calling this method whenever i am clicking on 'Get status' link.
public Vector getMaintenanceStatusList(){
Vector lockersStatus = null;
try {
Session sess = ToplinkDBUtils.getTopLinkSession();
sess.validateCache();
ReadAllQuery query = new ReadAllQuery();
query.dontCheckCache();
query.dontMaintainCache();
query.setReferenceClass(LockerMaintenanceStatus.class);
query.useDistinct();
lockersStatus = sess.readAllObjects(LockerMaintenanceStatus.class);
} catch (DatabaseException e) {
e.printStackTrace();
//******** Printing the updated value.
for (Iterator i = lockersStatus.iterator();i.hasNext();){
LockerMaintenanceStatus tmp = (LockerMaintenanceStatus)i.next();
System.out.println("Status value :: "+tmp.getStatus());
return lockersStatus;
Here, i am getting old status value for second time though i have updated the database with new status. (scenario if i work in same browser with same toplink session)
i am getting updated values only when i restart the JDEV oc4j.
Please let me know how i can solve the problem.
Thanks!
Veeraswami K

Veeraswami,
In your code you are constructing a query but are not executing it. Instead you are simply calling session.readAllObjects. The result of this call will be the cached versions (based on default cache config).
I would recommend doing:
ReadAllQuery query = new ReadAllQuery(LockerMaintenanceStatus.class);
query.refreshIdentityMapResult();
lockersStatus = (Vector) sess.executeQuery(query);The other settings you had used would bypass the cache and not result in its results being refreshed.
Doug

Toplink cache growing until OutOfMemoryError

Hello,
We are using OC4J 9.0.3 with toplink 9.0.3 on IBM AIX J2RE 1.3.1. From time to time, the JVM crashes with an OutOfMemoryError. Analysing the JVM heap dump, we have found that there are a lot of objects of the same type in the toplink cache:
# of objects: 48 047
Total size in bytes: 165 874 992
The identity map settings for the project caching this object type are:
Type: SoftCacheWeakIdentityMap
Size: 100
My understanding is that most of the 48 047 objects should be referenced as a weak references and that some of them should have been garbage collected by the VM instead of throwing an OutOfMemoryError.
Could it be a problem in the JVM garbage collector ?
May I use a CacheIdentityMap to work around the problem ?
Do you have any advice ?
Thank you in advance for any hint,
Pierre Laroche

Being in production I am not sure how much you can debug the system, but to determine if it is an issue with the weak references you could clear out the cache through an initializeAllIdentityMaps call on the session when the system is using most of the memory? This will remove all objects from the TopLink identity map removing the WeakReferences. This call should not be completed on a system still servicing requests though. Is it possible that there is a leak in the application that is preventing the WeakReferences from being garbage collected?
--Gordon

How to monitor Toplink cache ?

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