PPT-transactions and concurrency control

Sadhna Kumari OUTLINE ACID Properties 2Phase Commit Protocol TPS Serializability Concurrency Control Protocols Current Research Future References ACID PROPERTIES Atomicity A transaction is . This motivated an ongoing shared effort by the standards committees to specify concurrent behaviour in the next versions of both languages They aim to provide strong guarantees for racefree programs together with new but subtle relaxedmemory atomic Prof. O. Nierstrasz. Selected material © Magee and Kramer. © Oscar Nierstrasz. 2. Roadmap. Modelling Concurrency. Finite State Processes . Labelled Transition Systems. Java Threads. Thread creation. on Program . Analysis. Weizmann Institute . of Science. Guy Katz. and David . Harel. Overview. Program analysis: verification, repair, synthesis, . etc. Very desirable, but very difficult. State explosion. Median of a Triangle. A line segment connecting a vertex of a triangle to the midpoint of the opposite side. On a piece of graph paper, graph the triangle with vertices A(2, 1) B(5, 8) C(8, 3). . Find the midpoint of each side and label the midpoint opposite A “D”, opposite B “E”, opposite C “F”. . Concurrency Topics. 1. Sequential programming notation. 2. Expressing concurrency with . co. and . process. . 3. States and hardware. 4. Atomic actions. 5. Inter-leavings and histories. 6. The finite progress assumption. Database Concurrency Control. 1 Purpose of Concurrency Control. To enforce Isolation (through mutual exclusion) among conflicting transactions. . To preserve database consistency through consistency preserving execution of transactions.. Special rules due to the nature of the asset. Each shareholding in a company purchased on a separate date is treated as the acquisition of a separate asset for CGT purposes. The principle of first in/ first out (FIFO) applies to the disposal of shares of the same class. 1. Emmett . Witchel. The University of Texas At Austin. Q: When is everything happening?. A: Now. A: Concurrently. 2. Concurrency is central to CS. CS is at forefront of understanding concurrency. We operate near light speed. Introduction. Concurrency control protocols. Set of rules to guarantee serializability. Two-phase locking protocols. Lock data items to prevent concurrent access. Timestamp. Unique identifier for each transaction. Sadhna Kumari. OUTLINE. ACID Properties. 2-Phase Commit Protocol. TPS. Serializability. Concurrency Control Protocols. Current Research. Future. References. ACID PROPERTIES. Atomicity: . A . transaction is . Software & the Concurrency Revolution by Sutter & Larus ACM Queue Magazine, Sept. 2005 For CMPS 5433 - Halverson 1 In a Nutshell “The concurrency revolution is primarily a software revolution -. Bhavya. . Kilari. Dr. . Yanqing. Zhang, . CSc. 8320. PREVIEW. P. ART. I. : . I. NTRODUCTION. Transaction Processing System [. R. Chow & T. Johnson, 1997. Some slides adapted from . Navathe. et. Al. , . Silberchatz. et. Al and . Hector Garcia-Molina . Lock Based Protocols. A lock is a mechanism to control concurrent access to a data item. Data items can be locked in two modes :. Contents. Transaction. . control. Data Concurrency and Consistency in a Multiuser Environment. Locking. A Banking Transaction.               . Transactions - Rationale. Consider two clients booking airline tickets.