Deadlock Detection in Distributed Database Systems: A Performance

Evaluation Study

Prepared by:Ms. Pooja Mehta

ITSNS Branch,GTU-CDAC-BISAG ME Program,

Gandhinagar

Content2

Abstract Introduction Deadlock Detection Algorithms Performance Evaluation Performance Criteria Result Conclusion References

May 1, 2023By: Pooja Mehta

Abstract3

Three deadlock detection algorithms Fully Centralized Partially Distributed Fully Distributed

Partially Distributed Algorithm provides best performance.

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Introduction4

Deadlock What ? Where ? When ?

Deadlock Handling

Deadlock Resolution

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Deadlock Detection Algorithms5

1. Centralized Algorithm

Steps: -> Acquisition -> Free -> Detection

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Deadlock Detection Algorithms

2. Partially Distributed Algorithm

Tables: -> Allocation Table -> Local Transaction Table -> Resource Table

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Deadlock Detection Algorithms

3. Fully Distributed Algorithm

Detection of global deadlock Uses variable length tags for both resources and

transactions Uses WFG and two tags: “active” & “blocked”

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Performance Evaluation

Start-up queue Concurrency control queue Wait-for queue Resource queue

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Performance Criteria

Throughput Deadlock Life Time (DT) Deadlock Length (DL) The inter-site messages (IS) Storage Overhead (SO)

Results10

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When the number of concurrent transactions is low, the three deadlock detection algorithms perform alike, because conflicts are rare.

The fully distributed algorithm uses variable length messages.

The IS could be small, but the size could be large. The partially distributed algorithm uses fixed size

messages.

By: Pooja Mehta

Results11

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The centralized algorithm required the least period of time because, once the deadlock is formed, it is detected quickly since the detection is done at the central site.

The fully distributed algorithm required the most time to detect the deadlock because there is global detection.

The fully distributed and the partially distributed algorithms required the same duration of time to detect the cycle.

By: Pooja Mehta

Conclusion12

Varying the transaction size drastically affected the performance of the centralized and the fully distributed algorithms.

Deadlocks had the shortest life time in the centralized scheme.

This set of experiments showed that the overhead of deadlock detection, when deadlock exists, is only a small portion of the total overall cost.

May 1, 2023By: Pooja Mehta

References13

http://www3.physnet.uni-hamburg.de/physnet/Tru64-Unix/HTML/AQ0R5BTE/DOCU_005.html

http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=253375

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Thank you...!