Vector Clocks Collin J. Fidge, 1988. Timestamps in Message-Passing - PowerPoint PPT Presentation

Vector Clocks Collin J. Fidge, 1988. Timestamps in Message-Passing Systems That Preserve the Partial Order

Order of events without global clock What happens when? event message time process

A total order of events Lamport clocks 5 4 4 3 3 3 2 2 2 1 1 1 same timestamp: any (consistent) order

A total order of events Lamport clocks

A total order of events Lamport clocks Too little information: Shows only one possible interleaving of events.

A partial order of events The ”happens before” relation same process transitivity message minimal relation

A partial order of events The ”happens before” relation

A partial order of events Vector clocks A timestamp of a vector clock is a vector of integer clocks – one clock per process. • How does vector clocks work? • Can vector clocks represent the ”happens before” relation?

Vector clocks Rules �� [ � , � , . . . , � ] � ��

Vector clocks Rule 4 �� transit time out of order �� ( � [ � ] , � [ � ] + � ) �� = � � � � [ � ] = �� ( � [ � ] , � [ � ]) ��

Vector clocks Example [3 ,5 ,4] [4,0,0] [3 ,4,2] [3 ,0,0] [0,0,3] [3 ,3 ,2] [0,0,2] [0,2,2] [2,0,0] [0,0,1 ] [0,1,0] [1,0,0]

Vector clocks A relation on events �� → �� → � � ⇐ ⇒ � � � [ � ] < � � � [ � ] � ��

Vector clocks Example (again) � � → � � ⇐ ⇒ � � � [ � ] < � � � [ � ] [3 ,5 ,4] [4,0,0] same [3 ,4,2] process transitivity [3 ,0,0] [0,0,3] [3 ,3 ,2] message [0,0,2] [0,2,2] [2,0,0] [0,0,1 ] [0,1,0] [1,0,0] minimal relation

Vector clocks The ”happens before” relation �� → ��

Vector clocks The ”happens before” relation �� → � � �� [ � ] < � � � [ � ] � ��

Vector clocks The ”happens before” relation �� → � � �� [ � ] < � � � [ � ] � �� − � �� ( � � − � [ � ] , � � � [ � ] + � ) �� = � � � � [ � ] = �� ( � � − � [ � ] , � � � [ � ]) �� [ � ] < �� ( � � − � [ � ] , � � � [ � ] + � ) ��

Vector clocks The ”happens before” relation �� [ � ] < � � � [ � ] � �� = � �� [ � ] � � � � [ � ] � �� = � �� [ � ] � � � � [ � ] � �� [ � ] < � � � [ � ] � � � � [ � ] ��

Vector clocks The ”happens before” relation �� → �� → � � ⇐ ⇒ � � � [ � ] < � � � [ � ] �� [ � ] ��

Vector clocks Conclusion Vector clocks can describe the ”happens before” relation!

Vector Clocks Collin J. Fidge, 1988. Timestamps in Message-Passing - PowerPoint PPT Presentation

Vector Clocks Collin J. Fidge, 1988. Timestamps in Message-Passing Systems That Preserve the Partial Order Order of events without global clock What happens when? event message time process A total order of events Lamport clocks 5 4 4

Lamport Clocks Doug Woos Logistics notes Problem Set 1 due Friday Chandy-Lamport Snapshots

Recall our discussion of time CS514: Intermediate Course Logical clocks: represent part of

Vector Clocks in Coq An Experience Report Christopher Meiklejohn Basho Technologies, Inc.

Clocks Some clocks use motion to mark their intervals Others clocks dont appear to

Important Lessons Lamport & vector clocks both give a logical timestamps Total

Todays Topics Chapter 10. Clocks Physical Clocks. Synchronising physical clocks

Question: Clocks Youre bouncing gently up and down at the end of a springboard, without

Cold Atom Atom Clocks Clocks Cold Cold Atom Clocks and Fundamental Fundamental Tests Tests

Numb3rs 11 2 10 3 The Chinese Remainder Theorem 9 4 8 5 7 6 Chiming Clocks Two clocks,

Real clocks: a toy model for non-locality luis j. garay Universidad Complutense de Madrid

Gravitational Physics Physics Gravitational with with Optical Clocks Clocks in in Space

Distributed Systems events vs. physical clocks : time of day Assume no central time source

Time, Clocks, and State Machine Replication Dan Ports, CSEP 552 Todays question How

Clocks for 4.5G Radio Access Networks S E P T E M B E R 2 0 1 7 Complete Timing Portfolio

NOW Handout Page 1 1 Styles of Vector Architectures Components of Vector Processor Vector

Vector addition: The zero vector The D -vector whose entries are all zero is the zero vector ,

Motion Denoising with Application to Time-lapse Photography Michael Rubinstein MIT CSAIL Ce Liu

Awareness of MPI Virtual Process Topologies on the Single-Chip Cloud Computer Steffen Christgau,

1 Picking your Topic Please send me an email or make an appointment by October 1, with your

2016 Presenter: Glenn Lindsey VA7HC What were you doing at 1139 hours on Tuesday December 29,

Detecting and Using Critical Paths at Runtime in Message Driven Parallel Programs Isaac Dooley,

Turing Networks: Complexity Theory for Network? Message-Passing Parallelism Lower Bounds Upper

Distributed System Behavior Modeling of Urban Systems with Ontologies, Rules and Message Passing

Q-ary Repeat-Accumulate Codes for Weak Signals Communications Nico Palermo, IV3NWV XVII EME

Vector Clocks Collin J. Fidge, 1988. Timestamps in Message-Passing - PowerPoint PPT Presentation

Vector Clocks Collin J. Fidge, 1988. Timestamps in Message-Passing Systems That Preserve the Partial Order Order of events without global clock What happens when? event message time process A total order of events Lamport clocks 5 4 4

Lamport Clocks Doug Woos Logistics notes Problem Set 1 due Friday Chandy-Lamport Snapshots

Recall our discussion of time CS514: Intermediate Course Logical clocks: represent part of

Vector Clocks in Coq An Experience Report Christopher Meiklejohn Basho Technologies, Inc.

Clocks Some clocks use motion to mark their intervals Others clocks dont appear to

Important Lessons Lamport &amp; vector clocks both give a logical timestamps Total

Todays Topics Chapter 10. Clocks Physical Clocks. Synchronising physical clocks

Question: Clocks Youre bouncing gently up and down at the end of a springboard, without

Cold Atom Atom Clocks Clocks Cold Cold Atom Clocks and Fundamental Fundamental Tests Tests

Numb3rs 11 2 10 3 The Chinese Remainder Theorem 9 4 8 5 7 6 Chiming Clocks Two clocks,

Real clocks: a toy model for non-locality luis j. garay Universidad Complutense de Madrid

Gravitational Physics Physics Gravitational with with Optical Clocks Clocks in in Space

Distributed Systems events vs. physical clocks : time of day Assume no central time source

Time, Clocks, and State Machine Replication Dan Ports, CSEP 552 Todays question How

Clocks for 4.5G Radio Access Networks S E P T E M B E R 2 0 1 7 Complete Timing Portfolio

NOW Handout Page 1 1 Styles of Vector Architectures Components of Vector Processor Vector

Vector addition: The zero vector The D -vector whose entries are all zero is the zero vector ,

Motion Denoising with Application to Time-lapse Photography Michael Rubinstein MIT CSAIL Ce Liu

Awareness of MPI Virtual Process Topologies on the Single-Chip Cloud Computer Steffen Christgau,

1 Picking your Topic Please send me an email or make an appointment by October 1, with your

2016 Presenter: Glenn Lindsey VA7HC What were you doing at 1139 hours on Tuesday December 29,

Detecting and Using Critical Paths at Runtime in Message Driven Parallel Programs Isaac Dooley,

Turing Networks: Complexity Theory for Network? Message-Passing Parallelism Lower Bounds Upper

Distributed System Behavior Modeling of Urban Systems with Ontologies, Rules and Message Passing

Q-ary Repeat-Accumulate Codes for Weak Signals Communications Nico Palermo, IV3NWV XVII EME

Important Lessons Lamport & vector clocks both give a logical timestamps Total