Case 2 : Deadlocks in Databases

Case 2 : Deadlocks in Databases

•          Deadlock can occur if 2 processes access & lock records in database.

•          3 different levels of locking :

–        entire database for duration of request

–        a subsection of the database

–        individual record until process is completed.

•          If don’t use locks, can lead to a race condition.

Example:

1.            P1 accesses R1 and locks it.

2.            P2 accesses R2 and locks it.

3.            P1 requests R2, which is locked by P2.

4.            P2 requests R1, which is locked by P1.