File:Lamport-Clock-en.svg

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Summary

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Example for the working of a lamport logical clock, showing the causality of events (happened-before relation).

Explanation

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  • A, B and C are processes (oder places)
  • A1, A2 ... C5 are events or activites in that process (resp. at that place)
  • The boxes at the events give the current value of the Lamport clock of that process at the given point in time.
  • The arrows represent the passing of messages (resp. effects or data) between the processes (resp. places)
  • The dark blue (resp. dark red) areas represent the cause (resp. the effect) of the event B4.
  • The light blue (resp. light red) areas represent events, that are considered to be causes or effects of B4 by the lamport clock, but are in fact independent (or concurrent)

Events are concurrent to (independend of) B4, if no information flows to or from that event from or to B4. It's easy to see that the lamport clock does not recognize some of the events as independent, even though they are. This is because the Lamport clock only satisfies the weak clock condition (see logical clock).

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Licensing

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I, the copyright holder of this work, hereby publish it under the following licenses:
GNU head Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License.
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Under the following conditions:
  • attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
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This licensing tag was added to this file as part of the GFDL licensing update.
w:en:Creative Commons
attribution share alike
This file is licensed under the Creative Commons Attribution-Share Alike 2.5 Generic, 2.0 Generic and 1.0 Generic license.
You are free:
  • to share – to copy, distribute and transmit the work
  • to remix – to adapt the work
Under the following conditions:
  • attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
  • share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.
You may select the license of your choice.

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Date/TimeThumbnailDimensionsUserComment
current13:19, 23 June 2006Thumbnail for version as of 13:19, 23 June 2006744 × 438 (26 KB)Duesentrieb (talk | contribs)Example for the working of a lamport logical clock, showing the causality of events (''happened-before'' relation).

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