Analysis and Evaluation of Two-Phase Locking (2PL)

Handling of deadlocks

A situation might arise where transaction A is waiting for a long time for transaction B to finish, since we use a lot of locks simultaneously. In general, we refer to the situation where a cycle of transactions waits for one another to release locks as a deadlock.

The database automatically identifies deadlocks among the transactions. To resolve them, it relies on two approaches—detection and prevention.

Deadlocks detection

The database management system (DBMS) produces a waits-for graphA directed graph used for deadlock detection., where transactions will form the nodes. Consequently, an edge will form between two nodes, Ti and Tj, if Ti is waiting for the release of a lock ...