3. Deadlock Detection
• Centralized
– Single point of failure
– bottleneck
• Distributed
– Soojung Lee
– Monjurul Alom et al
– Farajzadeh et al
4. Introduction
• Process dependency
– wait-for graph (WFG)
• Request model
– AND
– OR
– p out-of q
• Communication model
– Just message communication
– Bounded delay, reliable protocol
5. Soojung Lee
• Dependency Model
– Reduced wait-for graph (RWFG)
– knot
• Request model
– OR
• Blocked process can participate in deadlock
detection algorithm
9. Monjurul Alom et al
• Distributed Database System
• Dependency model
– Transaction wait-for graph (TWFG)
• Request model
– AND
• Linear Transaction Structure (LTS)
• Distributed Transaction Structure (DTS)
10. Algorithm Scheme
• LTS for each local site
• DTS for global resource transaction
communication
• Priority Id for each transaction in each of the
sites
• The local and global cycles
• Abort of the victim transaction based on the
cycles
17. Farajzadeh et al
• History-based edge chasing
– Probe message
• Request model
– p out-of q
• Messages
– Probe
– Clean-up
– Ok
– Deny
18. Algorithm
• Receive probe
– In memory and id = received id
• Prefix of received route-string
– deadlock
• Otherwise
– Save probe with smaller path-string and propagate received
probe
• Deadlock
– Initiator
• Clean-up and suicide
– Otherwise
• Request permission for suicide
19.
20. Comparison
• First an third algorithm
– Both use probe messages
– Build WFG
– Different in message number, delay, message size
and resolution scheme
Sujung lee farajzadeh
Number of
message
2e <=e
Message size d+2 <=O(d)
delay O(dlogn) n
resolutaion yes Yes, 2 message
e : number of edge in WFG, n : number of node, d : diameter of WFG