About WRITE
Locking in JPA
Explains how to use optimistic locking and pessimistic locking in JPA.... represents a shared lock. PESSIMISTIC_WRITE LockModeType.PESSIMISTIC_WRITE enum constant Pessimistic write lock. See JavaDoc ...
commit()
Commit the current resource transaction, writing any unflushed changes to the database.(Method of javax.persistence.EntityTransaction)
LockModeType.WRITE
Synonymous with OPTIMISTIC_FORCE_INCREMENT.(Enum Constant of javax.persistence.LockModeType)
LockModeType.PESSIMISTIC_WRITE
Pessimistic write lock.(Enum Constant of javax.persistence.LockModeType)
Optimistic locking failure
Optimistic locking failure: I am using a Semaphore to force this execution of concurrents transactions T1 and T2 that cause parallel updates to A/B but it does not throw an OptimisticLockException and roll back. ... + B + 20 | WRITE ( B ) version = 2 value = 20 A = A + B + 10 | WRITE ( A ) version = 2 value = 10 | ...
LockModeType.PESSIMISTIC_FORCE_INCREMENT
Pessimistic write lock, with version update.(Enum Constant of javax.persistence.LockModeType)
Storing JPA Entity Objects
Explains how to use JPA to store (persist) entity objects in the database. New entity objects can be stored in the database either explicitly by invoking the persist persist(entity) EntityManager's method Make an instance managed and persistent. See JavaDoc Reference Page... method or ...
Occasionally slow requests in load testing
We are running load testing against objectdb version 2.3.7_18. The performance is generally OK, however there are quite a few "spikes" in the performance where we are getting a lot of very slow response times from the DB, around 10 - 15 seconds. Looking at the DB server process with AppDynamics we can see that most of the requests get stuck in one of 2 places: com.objectdb.o.PGC:w: line number 232 com.objectdb.o.LFL:U: line number 1068 Please see the attached callgraph examples for full stack trace examples. ... sync = "false" path = "." mode = "write" /> <locking version-check = "true" /> ... takes up to 10 seconds. I've also noticed a large IO write spike at the same time the issue has started (picture also attached), but ...
best practice for DB recovery
Hi, I'm trying to come up with the best approach for supporting some kind of hot standby for my master DB. ... them to my persistence unit but being able to read and not write is a condition that can't last for more than a few minutes and have ... have two(or more) entity managers in my DAO layer and write all changes to both instances(may have IDs synchronization issues), if ...
javax.jdo.spi.PersistenceCapable
A class that can be managed by a binary-compatible JDO implementation must implement this interface.(Interface of JDO)
