Distributed deadlocks : Distributed deadlocks Sindoora
CONTENT : CONTENT Definitions
Strategies for handling deadlocks
Deadlock Detection
Approaches for deadlock detection
Existing algorithms
Deadlock Resolution
OR model
AND model
Definition : Definition Deadlock:
A deadlock is a situation in which two computer programs sharing the same resource are effectively preventing each other from accessing the resource, resulting in both programs ceasing to function.
Distributed deadlocks:
This event occurs when two programs residing on separate computers are deadlocked. Deadlocks in distributed systems. are harder to avoid, prevent or even detect
Handling Deadlocks : Handling Deadlocks There are four strategies for handling deadlocks
Deadlock prevention
Deadlock avoidance
Deadlock detection
Deadlock resolution
Distributed Deadlock Detection : Distributed Deadlock Detection The AND model:
A process or transaction can simultaneously request multiple resources.
Remains blocked until all the requested resources are allocated.
- Cycle is sufficient to declare deadlock
The OR model:
A process or transaction can simultaneously request multiple resources.
Remains blocked until any one of the requested resource is allocated.
- Knot is sufficient to declare deadlock
Distributed Deadlock Detection : Distributed Deadlock Detection Approaches fall under three categories
Centralized Control
Distributed Control
Hierarchal Control
Algorithms for deadlock detection : Algorithms for deadlock detection Ho-Ramamoorthy Algorithm
Path-pushing algorithm
Edge-chasing algorithm
Diffusion Computation
Global state detection
The Menasce-Muntz Algorithm
Deadlock Resolution Algorithms : Deadlock Resolution Algorithms OR model:
Never causes false deadlock resolutions
Each process issues request to multiple resources
Remains blocked until any one of the resource is allocated
Request, reply, cancel are the three requests that flow throughout the execution
AND model:
Only true deadlocks are resolved.
The node specific variables used are status, version, create, transmitted, to_reply.
Three types of messages are handled by the algorithm probes, information messages, reply messages.
Distributed deadlock resolution algorithms for AND & OR models : Distributed deadlock resolution algorithms for AND & OR models OR model algorithm execution: (7, t_init7, 7, t_block7, 1, path) (5, t_init5, notify)
Distributed deadlock resolution algorithms for AND & OR models : Distributed deadlock resolution algorithms for AND & OR models AND model algorithm execution:
Queries ? : Queries ?
Thank you : Thank you