About PESSIMISTIC_WRITE

manual

Locking in JPA

Explains how to use optimistic locking and pessimistic locking in JPA.... - which represents a shared lock. PESSIMISTIC_WRITE LockModeType.PESSIMISTIC_WRITE enum constant Pessimistic write lock. See ...

 
api-jpa

LockModeType.PESSIMISTIC_WRITE

Pessimistic write lock.(Enum Constant of javax.persistence.LockModeType)

 
forum_thread

"Attempt to lock a non entity object" error

Probably a simple answer for someone who's been using ObjectDB for awhile: I'm reading objects from the database outside a transaction (inside doesn't seem to matter). First cycle of doEdit and then doCancelEdit works fine. Second time I doEdit produces the error "Attempt to lock a non entity object" session.rollback() is somehow causing the problem (found through debugging) Is this enough information for someone to suggest what might be happening and how to fix it? ... ( ) , LockModeType . PESSIMISTIC_WRITE ) ; . . } //doEdit ... ; em. lock ( p, LockModeType . PESSIMISTIC_WRITE ) ; System. out . println ( ... em. lock ( p, LockModeType . PESSIMISTIC_WRITE ) ; System. out . println ( ...

 
forum_thread

Database Inconsistency or corruption

Hi, since a week I have been trying to find a solution to a strange problem. We are using ObjectDB 2.6.8_02 im embedded mode. The problem is that data gets lost when updating an entity. 1-) Background Consider Three entities: ObjectValue, Attribute and Value. ObjectValue has a one to many relationship to Attribute and Attribute has a one to one relationship to Value. ... TYPE:=Person, REVISION:=0, isPersisted:=true, LockMode:=PESSIMISTIC_WRITE]] ... Attribute  ID:=1400, ... TYPE:=Person, REVISION:=2, isPersisted:=true, LockMode:=PESSIMISTIC_WRITE]] ... Attribute  ID:=1400, ...

 
api-jpa

javax.persistence.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.(Enum of JPA)

 
manual

Setting and Tuning of JPA Queries

Explains various JPA query settings - result range, flush and lock.... method. See JavaDoc Reference Page... . PESSIMISTIC_WRITE LockModeType.PESSIMISTIC_WRITE enum constant Pessimistic write lock. See ...

 
issue

Pessimistic lock timeout - blocks indefinitely

I've attached a simple test which creates an object then kicks off several threads which each try to update the object. I'm using a pessimistic lock with timeout as follows: ... ( MyEntity. class , 1 , LockModeType . PESSIMISTIC_WRITE , properties ) ; One thread manages to do ...

 
issue

InternalException during producer/consumer scenario

Hi, I'm trying to use objectdb in a producer/consumer scenario. Producer threads put message objects into a table while consumer threads remove the objects based on age, priority, etc. There are 2 main motivations for using objectdb for this purpose rather than a queue or similar data structure: 1) The consumer can select the "next" object based on a range of potentially complex criteria. 2) The number of objects produced can be potentially exceed available memory so can be held on disk within the objectdb file. ... on a query with MaxResults set to 1 and LockMode set to PESSIMISTIC_WRITE. This results in the exceptions below. Could you ...

 
forum_thread

How to do multithreading with embedded ObjectDB

Hi, I've tried to implement a counter with ObjectDB, but the following code doesn't work as expected: ... ( Point. class , 1 , LockModeType . PESSIMISTIC_WRITE ) ; point. setX ( point. getX ...

 
issue

Threaded Test - Failed to commit transaction: Unexpected internal exception

Hi I'm trying to create a simple producer-consumer queue scenario but am getting the followin exception: ... ( LockModeType . PESSIMISTIC_WRITE ) . getSingleResult ( ) ; ...