Which EntityManager API will lock entity x with a pessimistic lock?

The correct answer is C. em.lock(x, LockModeType.PESSIMISTIC_READ). Setting a Pessimistic Lock An entity object can be locked explicitly by the lock method: em.lock(employee, LockModeType.PESSIMISTIC_WRITE); The first argument is an entity object. The second argument is the requested lock mode. A LockTimeoutException is thrown if the requested…

EntityManager Operations

Question

Options

Aem.lock(x, LockModeType.WRITE)
Bem.lock(x, LockModeType.PESSIMISTIC)
Cem.lock(x, LockModeType.PESSIMISTIC_READ)
Dem.lock(x, LockModeType.OPTIMISTIC_FORCE_INCREMENT)

How the community answered

(18 responses)

A
6% (1)
B
17% (3)
C
72% (13)
D
6% (1)

Explanation

Setting a Pessimistic Lock An entity object can be locked explicitly by the lock method: em.lock(employee, LockModeType.PESSIMISTIC_WRITE); The first argument is an entity object. The second argument is the requested lock mode. A LockTimeoutException is thrown if the requested pessimistic lock cannot be granted: *A PESSIMISTIC_READ lock request fails if another user (which is represented by another EntityManager instance) currently holds a PESSIMISTIC_WRITE lock on that database object. *A PESSIMISTIC_WRITE lock request fails if another user currently holds either a PESSIMISTIC_WRITE lock or a PESSIMISTIC_READ lock on that database object.

Topics

#pessimistic locking#LockModeType#EntityManager.lock#PESSIMISTIC_READ

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