|< < 32 > >|

Strict Two-Phase Locking

Deadlock

Avoid deadlock

• Suppose that the objects that can be locked are ranked: x₁, ... x_n.

• And suppose that locks are obtained in that order.

• I.e., if you have locked x_i and nothing after it, then:
  • You can request lock x_j, j > i.
  • You cannot request lock x_j, j < i.

Cycles cannot form, since all waits-for arrows go in the same direction.

|< < 32 > >|