Database System Concepts
Database System Concepts
7th Edition
ISBN: 9780078022159
Author: Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher: McGraw-Hill Education
Expert Solution & Answer
Book Icon
Chapter 23, Problem 8PE

Explanation of Solution

Deadlock-detection algorithm:

Consider the given deadlock-detection algorithm:

  • Let a cycle, Ti -> Tj -> Tm -> Ti exists in the graph, which is built by the controller.
  • The edges in the graph will be local edges either from (Tk, Tl) or a distributed edge of the form (Tk, Tl, n).
  • Every local edge (Tk, Tl) certainly means Tk 's waiting for Tl.
  • Since a distributed edge (Tk, Tl, n) is only inserted into the graph if Tk's request reaches Tl and Tis unable to release the lock instantly, Tis going to have to wait for Tto free up the resources.
  • Every edge of the cycle therefore truly represents a transaction waiting for yet another.

Proving the converse implication:

  • As soon as it is found out that Tis waiting for Tl:
    • If both Tk and Tare located at same site, that is either S1 S3, a local edge between Tand Tl is inserted...

Blurred answer
Knowledge Booster
Background pattern image
Recommended textbooks for you
Text book image
Database System Concepts
Computer Science
ISBN:9780078022159
Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
Publisher:McGraw-Hill Education
Text book image
Starting Out with Python (4th Edition)
Computer Science
ISBN:9780134444321
Author:Tony Gaddis
Publisher:PEARSON
Text book image
Digital Fundamentals (11th Edition)
Computer Science
ISBN:9780132737968
Author:Thomas L. Floyd
Publisher:PEARSON
Text book image
C How to Program (8th Edition)
Computer Science
ISBN:9780133976892
Author:Paul J. Deitel, Harvey Deitel
Publisher:PEARSON
Text book image
Database Systems: Design, Implementation, & Manag...
Computer Science
ISBN:9781337627900
Author:Carlos Coronel, Steven Morris
Publisher:Cengage Learning
Text book image
Programmable Logic Controllers
Computer Science
ISBN:9780073373843
Author:Frank D. Petruzella
Publisher:McGraw-Hill Education