Deadlock Avoidance

Deadlock avoidance involves dynamically checking whether resource allocation requests could lead to a deadlock and only granting requests that maintain a safe state. Unlike prevention which designs constraints into the system, avoidance makes decisions at runtime based on the current system state. The main deadlock avoidance algorithm is the Banker's Algorithm, which requires that processes declare their maximum resource needs in advance. The algorithm maintains information about available resources, allocated resources, and maximum demands. Before granting a resource request, the algorithm checks if the resulting state would be safe - meaning there exists a sequence (safe sequence) in which all processes can complete without deadlock. A state is safe if the system can allocate resources to each process in some order and still avoid deadlock. The Banker's Algorithm has some limitations: it requires knowledge of maximum resource needs in advance, it can be computationally expensive for large systems, and it assumes a fixed number of resources. Other avoidance techniques include resource allocation graphs with claim edges, which work well for systems with single instances of each resource type. Deadlock avoidance provides better resource utilization than prevention but requires more runtime overhead and advance knowledge of process behavior.