In a distributed system deadlock can neither be prevented nor avoided as the system is so vast that it is impossible to do so. Therefore, only deadlock detection can be implemented. The techniques of deadlock detection in the distributed system require the following:
· Progress – The method should be able to detect all the deadlocks in the system.
· Safety – The method should not detect false or phantom deadlocks.
There are three approaches to detect deadlocks in distributed systems. They are as follows:
1. Centralized approach –
In the centralized approach, there is only one responsible resource to detect deadlock. The advantage of this approach is that it is simple and easy to implement, while the drawbacks include excessive workload at one node, single-point failure (that is the whole system is dependent on one node if that node fails the whole system crashes) which in turns makes the system less reliable.
- Distributed approach –
In the distributed approach different nodes work together to detect deadlocks. No single point failure ( that is the whole system is dependent on one node if that node fails the whole system crashes) as the workload is equally divided among all nodes. The speed of deadlock detection also increases. - Hierarchical approach –
This approach is the most advantageous. It is the combination of both centralized and distributed approaches of deadlock detection in a distributed system. In this approach, some selected nodes or cluster of nodes are responsible for deadlock detection and these selected nodes are controlled by a single node.
