34-deadlock

Implementing Deadlock

A deadlock occurs when multiple transactions are stuck waiting for each other to release locks, creating a cycle of dependencies where no progress can be made.

Deadlock Example:

In the scenario depicted:

• T2 wants Record 8, but T1 holds the lock.
• T1 wants Record 0, but T3 holds the lock.
• T3 wants Record 8, causing a circular wait.

Deadlock Prevention:

To prevent deadlocks, acquire locks in a strict, predefined order based on row indices. For example:

if row1 > row2 {
    tmp := row1
    row1 = row2
    row2 = tmp
}

This ensures consistent ordering of lock acquisition, breaking circular dependencies and avoiding deadlocks.