[jboss-user] [JBossCache] - Re: JBossCache and readonly transactions
- REPLICATION mode replicates everything is put inside the cache. This is bad because replicates everything, also objects that have not been modified, generating unnecessary traffic. - INVALIDATION mode tags objects that are out of date. This is bad because objects have to be reloaded into cache accessing the database. I think it would be better an hybrid approach: simply replicate changes. Andrea View the original post : http://www.jboss.com/index.html?module=bbop=viewtopicp=4038803#4038803 Reply to the post : http://www.jboss.com/index.html?module=bbop=postingmode=replyp=4038803 ___ jboss-user mailing list jboss-user@lists.jboss.org https://lists.jboss.org/mailman/listinfo/jboss-user
[jboss-user] [JBossCache] - Re: JBossCache and readonly transactions
Caching read-only data is a good thing if it is done locally, but i don´t understand why should we replicate them to all nodes in the cluster. Scalability and good performances can be achieved only if we reduce the amount of informations sent to the channel. So imagine that a transaction performs a SELECT * FROM T, where T is a table containing 1.000.000 of records, this transaction would produce an incredible and not necessary traffic on the communication channel, decreasing scalability and performances of the all cluster. isn´t it? Andrea View the original post : http://www.jboss.com/index.html?module=bbop=viewtopicp=4038253#4038253 Reply to the post : http://www.jboss.com/index.html?module=bbop=postingmode=replyp=4038253 ___ jboss-user mailing list jboss-user@lists.jboss.org https://lists.jboss.org/mailman/listinfo/jboss-user
[jboss-user] [JBossCache] - JBossCache transaction isolation levels
hi all,
i am testing JBossCache (version 1.4.1.SP3) Transaction Isolation levels. For
this reason i have developed a simple test application that creates 2 threads
that concurrently perform local transactions. All the examples have been done
with Postgres-8.2.1, and everytime i have changed JBossCache Transaction
Isolation level, i have changed the corresponding one in the database.
Thread 1: looks for a bean with primary key 1 and prints it, then sleeps for 2
seconds. when it wakes up, looks again for bean with primary key 1 and prints
it.
Thread 2: creates and persist a bean with primary key 1.
Everytime Thread 1 starts its execution before Thread 2.
| @TransactionAttribute(TransactionAttributeType.REQUIRED)
| public void doTransaction(int id) throws Exception {
| System.out.println(id + : start transaction);
|
| // Thread 2
| if((id % 2) == 0) {
| em.persist(new Tx(1, 0, adapt19));
| System.out.println(id + : inserted 1);
| }
| // Thread 1
| else {
| Tx tx = em.find(Tx.class, 1);
| System.out.println(id + : + tx);
| Thread.currentThread().sleep(2000);
| tx = em.find(Tx.class, 1);
| System.out.println(id + : + tx);
| }
|
| System.out.println(id + : end transaction);
| } catch(Exception e) {e.printStackTrace();}
|
Serializable: ok
Repeatable read: no
| 1: start tx
| 2: start tx
| 1: null
| 2: inserted 1
| 2: end tx
| 1: 1, 0, adapt19 [should be null]
| 1: end tx
|
Read committed: ok
Read uncommitted: no (When trying to test this Isolation level i have inserted
a delay in Thread 2 to make it commit after Thraed 1)
| 1: start tx
| 1: null
| 2: start tx
| 2: inserted 1
| 1: null [shuold be 1, 0, adapt19]
| 1: end tx
| 2: end tx
|
Now my question is: is there something wrong with JBossCache Transaction
Isolation levels, or something wrong with my test application?
Thank you very much
Andrea
View the original post :
http://www.jboss.com/index.html?module=bbop=viewtopicp=4036036#4036036
Reply to the post :
http://www.jboss.com/index.html?module=bbop=postingmode=replyp=4036036
___
jboss-user mailing list
jboss-user@lists.jboss.org
https://lists.jboss.org/mailman/listinfo/jboss-user
[jboss-user] [JBossCache] - use of org.hibernate.cache.UpdateTimestamp
hi all, i am using JBossCache (1.4.1.SP3) and i am trying to understand how it works. looking at the printDetails() function of the JBossCache bean in the JBoss JMX-Console, i have noticed that org.hibernate.cache.UpdateTimestamp..item is updated everytime with the timestamp of the last modification of the corresponding table. i would like to know why this timestamp is needed by JBossCache. thank you very much Andrea View the original post : http://www.jboss.com/index.html?module=bbop=viewtopicp=4035756#4035756 Reply to the post : http://www.jboss.com/index.html?module=bbop=postingmode=replyp=4035756 ___ jboss-user mailing list jboss-user@lists.jboss.org https://lists.jboss.org/mailman/listinfo/jboss-user
[jboss-user] [JBossCache] - JBossCache concurrent transaction management
Hi everyone, i am trying to understand how concurrent transactions are managed by JBossCache. I have developed a simple EJB3 application that i am testing on a cluster of JBoss-4.0.5 instances. it creates a certain amount of threads that perform concurrent modification and creation of EntityBeans on different nodes of the cluster, sharing a common DB (PostgreSQL-8.2.1). several scenarios have arised when two transactions try to concurrently create the same EntityBean on different nodes of the cluster: 1) sometimes they stop their execution till a timeout expire (ERROR [IdentityLock] write lock for /server/Book/server.Book#4 could not be acquired after 15000 ms), when one of them is able to committ its transaction. it looks like both are waiting the other to acquire lock: a deadlock that is broken only when timeout exception arises. 2) sometimes one of them is aborted because of duplicate key violation (ERROR: duplicate key violates unique constraint book_pkey. ERROR [JDBCExceptionReporter] Batch entry 0 insert into BOOK (TITLE, AUTHOR, ID) values (Fiesta, Hernest Hemingway, 5) was aborted. Call getNextException to see the cause.). 3) sometimes one of them is aborted beacuse of PersistenceException (ERROR: PersistenceException, org.hibernate.PersistentObjectException: detached entity passed to persist: server.Book). what i don´t understand is: - why exception (1) arises? - what is the difference between exception (2) and (3)? is that in exception (2) transaction is aborted at DB level, when performing INSERT operation, instead in exception (3) it is aborted at AS level, when creating the EntityBean? finally i would like to know if it exists a document where it is deeply described how transactions are managed by JBossCache inside a cluster. many thanks Andrea View the original post : http://www.jboss.com/index.html?module=bbop=viewtopicp=4033618#4033618 Reply to the post : http://www.jboss.com/index.html?module=bbop=postingmode=replyp=4033618 ___ jboss-user mailing list jboss-user@lists.jboss.org https://lists.jboss.org/mailman/listinfo/jboss-user
[jboss-user] [JBossCache] - Re: JBossCache concurrent transaction management
i forgot to specify my JBossCache (version1.4.0.SP1) EntityBeans configuration: - NodeLockingScheme: PESSIMISTIC - IsolationLevel: REPEATABLE_READ - CacheMode: REPL_SYNC Andrea View the original post : http://www.jboss.com/index.html?module=bbop=viewtopicp=4033638#4033638 Reply to the post : http://www.jboss.com/index.html?module=bbop=postingmode=replyp=4033638 ___ jboss-user mailing list jboss-user@lists.jboss.org https://lists.jboss.org/mailman/listinfo/jboss-user
[jboss-user] [Clustering/JBoss] - Cannot persist replicated EntityBeans
Hi everyone, i have a cluster of JBoss instances (version 4.0.5), each of them having its own local database copy. I have developed a simple EJB3 application that tryes to insert datas inside a database to test the behaviour of JBoss replication. The application ends without problems, all datas are written inside local database and corresponding EntityBeans are well replicated by JBossCache to other nodes, but replicated EntityBeans are not written to database by other replicas. I cannot understand if the problem is that this feature has not yet been implemented or there is something wrong with my configuration files. thank you very much Andrea View the original post : http://www.jboss.com/index.html?module=bbop=viewtopicp=4032689#4032689 Reply to the post : http://www.jboss.com/index.html?module=bbop=postingmode=replyp=4032689 ___ jboss-user mailing list jboss-user@lists.jboss.org https://lists.jboss.org/mailman/listinfo/jboss-user
[jboss-user] [Persistence, JBoss/CMP, Hibernate, Database] - cannot persist replicated entity beans
Hi everyone, i have a cluster of JBoss instances (version 4.0.5), each of them having its own local database copy. I have developed a simple EJB3 application that try to insert datas inside a database to test the behaviour of JBoss replication. The application ends without problems, all datas are written inside local database and corresponding EntityBeans are well replicated by JBossCache to other nodes, but replicated EntityBeans are not written to database by other replicas. I cannot understand if the problem is that this feature has not yet been implemented or there is something wrong with my configuration files. thank you very much Andrea View the original post : http://www.jboss.com/index.html?module=bbop=viewtopicp=4032038#4032038 Reply to the post : http://www.jboss.com/index.html?module=bbop=postingmode=replyp=4032038 ___ jboss-user mailing list jboss-user@lists.jboss.org https://lists.jboss.org/mailman/listinfo/jboss-user
