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JPA 2 supports both optimistic locking and pessimistic locking . Locking is essential to avoid update collisions resulting from simultaneous updates to the same data by two concurrent users. Locking ... is locked separately. Optimistic locking is applied on transaction commit. Any database object

. Therefore, when performance is important, this issue has to be considered. Lock Mode (setLockMode) ObjectDB uses automatic optimistic locking to prevent concurrent changes to entity objects by multiple users. JPA 2 adds support for pessimistic locking . The setLockMode method sets a lock mode that has to be applied

this is the result of a lock ) when I try to close the persistence manager, but only if 'retainValues' is set ... ) - locked (a java.io.BufferedInputStream) at java.io.FilterInputStream.read(FilterInputStream.java:83 ... ) Locked ownable synchronizers: - locked (a java.util.concurrent.ThreadPoolExecutor$Worker) "RMI TCP

Hi,   I realise that JPA2 doesn't necessarily define a standard API way for Lock Timeouts. However, there is a standardised query 'hint' that can be setup to make the underlying DB lock a record for a specific time. The hint property is: "javax.persistence. lock .timeout" I have a situation

that are just doing simple queries (just selects, no update or delete ...) show locks like these (question is: why there are locks and how could we get rid of that):   log1: "qtp1523553211-271" #271 prio ... to lock (a com.objectdb.o.LFL) at com.objectdb.o.PAG.au(PAG.java:928) at com.objectdb.o.PGC.C(PGC.java:281

. Our approach to this was to use Objectdb's pessimestic locking . This seems to work, but if the owner of the current pessimestic lock abruptly quits without releasing the lock it doesn't get released.    Is there anyway the server can detect that a client ( lock owner is no longer connected

JPA Method in javax.persistence.EntityManager void lock (   Object entity,     LockModeType  lockMode,    Map  properties ) Lock an entity instance that is contained in the persistence context with the specified lock mode type

JPA Method in javax.persistence.EntityManager void lock (   Object entity,     LockModeType  lockMode ) Lock an entity instance that is contained in the persistence context with the specified lock mode type. If a pessimistic lock mode type is specified

and then doCancelEdit works fine. Second time I doEdit produces the error "Attempt to lock a non entity ... {     session.beginTransaction();     session. lock (subjectJList ... ------------------------------------------------------------- Attempt to lock a non entity object   AlphaOne Ron Brennan Error was caused

thread titled, "Sample JDO Architecture for Follow Up Questions".   Questions about blocking/ locking ... is actually blocking/ locking so I might adapt to achieve better concurrency. 1) Where are locks when accessing PersistenceManager by multiple threads? 2) Does it lock at PersistenceManager

wherein the EntityManagerFactory objects are being locked during EntityManager object creation.  Please refer ... ; at com.objectdb.o.OMF.w(OMF.java:674)         - waiting to lock ( a com.objectdb ... ; - locked (a java.io.BufferedInputStream)         at com.objectdb.o.NTS.n(NTS.java:324

Hi, I seem to be getting a lot of these optimistic locking errors: Caused by: com.objectdb.o._OptimisticLockException: Optimistic lock failed for object Is there any way to force the database to use pessimistic locking only? I've tried various xml configurations, and also various transaction

Hi   I have tested pesimistic lock and the result was for me unexpected. In the first ... an exceptopn that lock could not be granted, quite nice but in that moment I wanted commit the first transaction and I also got lock exception. this the test:   public void testPesimisticLock

We are having problems with optimistic locking . I made a simple test case to try to induce an optimistic lock . I have two users logged on to our system.  They both read and display the same ... . User 2 does not get an optimistic lock exception, so the database has user 2’s change

: Failed to commit transaction: Optimistic lock failed for object com.example.MyEntity#3 (object ... you, Carl     FastModel Ben Schreiber Hi, Locking in general is explained on: http://www.objectdb.com/java/jpa/persistence/ lock If you must avoid optimistic lock exceptions you can use

locking . When profiling our app in JVisualVm we notice a large number of threads are blocked ... : BLOCKED at com.objectdb.o.MST.Vb(MST.java:1293) - waiting to lock (a com.objectdb.o.LKM) owned by ... .o.LFL.R(LFL.java:996) at com.objectdb.o.SFL.ah(SFL.java:998) - locked (a com.objectdb.o.LFL) at com

. The locked file problem does not exist if I deploy the WebApplication on an local Glassfish server. How can I undeploy the application without getting the logfile locked ? // Parwing   parwing ... :/ locked . The problem from the begining was that because glassfish could't undeploy the webapp in

Optimistic locking failure: I am using a Semaphore to force this execution of concurrents ...   Thanks. eurojet P. F. Martinez Please explain the test output: Sequential=true Lock =WRITE ... ] WRITE B2 version=2 value=30 A1 version=2 value=10, B2 version=2 value=30 Sequential=false Lock =WRITE

It appears that EntityTransaction.commit() does not release a pessimistic lock - test code ... . You are right. Pessimistic locks are not released automatically (by default) on transaction commit. The reason ... and the application can still use them for further processing and update. Locks are released automatically

.OptimisticLockException Optimistic lock failed for object entities.Record#'1405/838/2011/121 ... .java:381) ... Thank you! adibe Adi Be Optimistic locking is explained in this manual page . support Support

. The second example is an OSGi program which fails with an optimistic lock exception. Both examples ... ). Can you explain the optimistic lock exception? It seems that the first level cache contains yet a dirty entity

.jdo.option.RestoreValues=false The DB2 returns the message "Optimistic lock failed for object" or ... ._JdoUserException: Attempt to lock an entity object by retrieval when no transaction is activ

Hello, I have an entity E with an attribute which is a collection of entities (one to many relationship) with an optimistic locking strategy supported by a version field. Is it possible to prevent the increment of the version of entity E when entities are added to or removed from the collection

hi, my current use case is: execute unit test, verify results in explorer. my problem, i have to close the explorer before every run, and open it again after the tests are done. this slows down the whole process. i opened the database in readonly mode, but the file will be locked by the explorer

Hello When I get an optimistic lock on an object, refresh(), start trans and persist?  Will the changes made to the object before the violation be retained or must they be duplicated in the retry code?  Assuming it affects only one object.  tia. cpanon CP The exact situation

is automatically increased by one. Version fields are used in conjunction with optimistic locking (as explained in the Locking in JPA section in chapter 3). You can expose entity object versions ... . Therefore, optimistic locking is supported by ObjectDB even when a version field is not defined

entity object, the nested exception is: Other common causes for RollbackException are lock failures ... , when a required entity object is not found: or during query execution: The lock exceptions (above) may also be thrown during retrieval, if database lock has been requested for retrieved entity objects and it cannot be granted.

Database is locked when in use

attribute of the element specifies if optimistic locking is enabled. Optimistic locking is completely

Detached entity objects are objects in a special state in which they are not managed by any EntityManager but still represent objects in the database. Compared to managed entity objects, detached objects are limited in functionality: Many JPA methods do not accept detached objects (e.g. lock

, including: Avoiding vendor lock in - switching between implementations is easy. Technology

of the ObjectDB engine (not using one server process), thus bypassing ObjectDB internal file lock protection

ObjectDB is an Object Oriented Database Management System (ODBMS). It provides all the standard database management services (storage and retrieval, transactions, lock management, query processing, etc.), but it uses an object oriented model to store and manage data. You can easily store ordinary

This chapter explains how to manage ObjectDB databases using the Java Persistence API (JPA). The first two pages introduce basic JPA interfaces and concepts: The next section explains how to use JPA for database CRUD operations: More advanced topics (e.g. locking and events) are discussed in the last section:

The ObjectDB Object Database ObjectDB is a powerful Object-Oriented Database Management System (ODBMS). It is compact, reliable, easy to use and extremely fast. ObjectDB provides all the standard database management services (storage and retrieval, transactions, lock management, query

 lockMode) Find by primary key and lock . Search for an entity of the specified class and primary key and lock it with respect to the specified lock type. If the entity instance is contained in ... if the lock method had been called on the entity. If the entity is found within the persistence context

.LockModeType Lock modes can be specified by means of passing a LockModeType argument to one of the javax.persistence.EntityManager methods that take locks ( lock , find , or refresh ) or to the Query.setLockMode() or TypedQuery.setLockMode() method. Lock modes can be used to specify either optimistic or

()) tr.rollback(); if (!pm.isClosed()) pm.close(); } Automatic Lock Management ObjectDB manages an automatic lock mechanism in order to prevent a database object from being modified by two different users ... transaction, on every retrieval of an object from the database a READ lock on that object

The two thread dumps show two different waiting situations. The first thread dump shows a page cache lock ... it is not a deadlock but a very short lock that is not expected to cause issues. The change in ... that there is no locking issue that prevents full usage of the available CPU). Could you please provide

.PessimisticLockScope Defines the values of the javax.persistence. lock .scope property for pessimistic locking . This property may be passed as an argument to the methods of the EntityManager , Query , and TypedQuery interfaces that allow lock modes to be specified or used with the NamedQuery annotation

key and lock . Search for an entity of the specified class and primary key and lock it with respect to the specified lock type. If the entity instance is contained in the persistence context, it is returned from there, and the effect of this method is the same as if the lock method had been called

; Map  properties ) Find by primary key and lock , using the specified properties. Search for an entity of the specified class and primary key and lock it with respect to the specified lock type ... there. If the entity is found within the persistence context and the lock mode type is pessimistic and the entity

LockModeType getLockMode () Get the current lock mode for the query. Returns null if a lock mode has not been set on the query object. Return: lock mode Throws: IllegalStateException - if the query ... value set and only the statement is rolled back TransactionRequiredException - if a lock mode

and hints Inherited from: Query Since: JPA 2.0 LockModeType getLockMode () Get the current lock mode for the query. Returns null if a lock mode has not been set on the query object. Return: lock mode ... is rolled back TransactionRequiredException - if a lock mode other than NONE has been set

the state of the instance from the database, overwriting changes made to the entity, if any, and lock it with respect to given lock mode type and with specified properties. If the lock mode type is pessimistic and the entity instance is found but cannot be locked : the PessimisticLockException will be thrown

to update the object. I'm using a pessimistic lock with timeout as follows: Map properties = new HashMap (); properties.put("javax.persistence. lock .timeout", 5000); MyEntity loaded = em.find(MyEntity ... a LockTimeoutException implying that the first lock wasn't released on the first commit

, overwriting changes made to the entity, if any, and lock it with respect to given lock mode type. If the lock mode type is pessimistic and the entity instance is found but cannot be locked : the PessimisticLockException will be thrown if the database locking failure causes transaction-level rollback

below. No other process had a lock on the file, especially as the server had just been rebooted

and Locks As explained in section 5.3 , ObjectDB manages an automatic lock mechanism in order ... relationship between object states and object locks . Only persistent transactional objects that are not new are locked . Therefore, a persistent object obj is locked only when the following expression

, because the database server manages an automatic lock mechanism. Embedded Mode In embedded mode ... that are added to the application's classpath. In this mode, the database file is locked for a single