Heart Beat Algorithm - Revision history

Admin: Reverted edits by Eboxytezi (Talk) to last version by Jfromm

2011-02-11T21:36:38Z

Reverted edits by Eboxytezi (Talk) to last version by Jfromm

← Older revision		Revision as of 16:36, 11 February 2011
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	A '''heartbeat algorithm''' or '''systolic algorithm''' is executed by a		A '''heartbeat algorithm''' or '''systolic algorithm''' is executed by a
	synchronous array of cells (~~"~~systolic array~~"~~) that perform only local computations		synchronous array of cells ("systolic array") that perform only local computations
	and communications. They are a special form of synchronous algorithms.		and communications. They are a special form of synchronous algorithms.
	Every node, process or processor exchanges data only with its direct neighbors,		Every node, process or processor exchanges data only with its direct neighbors,
	and data is flowing synchronously across the array. The names ~~"~~heartbeat~~"~~		and data is flowing synchronously across the array. The names "heartbeat"
	and ~~"~~systolic~~"~~ are chosen by analogy with the regular pumping of blood by the		and "systolic" are chosen by analogy with the regular pumping of blood by the
	heart in living organisms, ~~"~~systolic~~"~~ is the Greek word for ~~"~~to contract~~"~~ and		heart in living organisms, "systolic" is the Greek word for "to contract" and
	heartbeat. The asynchronous version of the heartbeat algorithm is		heartbeat. The asynchronous version of the heartbeat algorithm is
	named [[Phase Algorithm\|phase algorithm]].		named [[Phase Algorithm\|phase algorithm]].
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	indicating that a process is still active and alive.		indicating that a process is still active and alive.
	A heartbeat algorithm works with heartbeat messages for each node,		A heartbeat algorithm works with heartbeat messages for each node,
	and is characterized by ~~"~~rhythmic~~"~~ expansion and contraction of		and is characterized by "rhythmic" expansion and contraction of
	information. Each node behaves like a beating heart.		information. Each node behaves like a beating heart.

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	every node knows his neighbors. In the second round,		every node knows his neighbors. In the second round,
	every node knows his neighbors and their neighbors.		every node knows his neighbors and their neighbors.
	In each round the ~~"~~horizon~~"~~ is expanded by one ~~"~~hop~~"~~.		In each round the "horizon" is expanded by one "hop".
	After D rounds, where D equals the diameter of the		After D rounds, where D equals the diameter of the
	network, each node has informations about the whole		network, each node has informations about the whole
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	. declaration local Variables;		. declaration local Variables;
	. initialization local Variables;		. initialization local Variables;
	. wile (r~~<~~D) do		. wile (r<D) do
	. {		. {
	. // Synchronization		. // Synchronization
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	As [[Total Algorithm\|total algorithms]], heart beat or systolic algorithms		As [[Total Algorithm\|total algorithms]], heart beat or systolic algorithms
	can be used to spread and collect information in a distributed system.		can be used to spread and collect information in a distributed system.
	An example is the ~~"~~FloodMax~~"~~ algorithm, an [[Election_algorithm\|election algorithm]]		An example is the "FloodMax" algorithm, an [[Election_algorithm\|election algorithm]]
	which determines and selects the node with the highest ID in the system. In the		which determines and selects the node with the highest ID in the system. In the
	~~"~~FloodMax~~"~~ algorithm, each node informs his neighbors in each round about the node		"FloodMax" algorithm, each node informs his neighbors in each round about the node
	with the highest ID, receives in turn information from them, and updates its		with the highest ID, receives in turn information from them, and updates its
	information accordingly.		information accordingly.

	[[Category:Distributed Algorithms]]		[[Category:Distributed Algorithms]]

Eboxytezi at 02:53, 24 November 2010

2010-11-24T02:53:36Z

Jfromm: New page: A '''heartbeat algorithm''' or '''systolic algorithm''' is executed by a synchronous array of cells ("systolic array") that perform only local computations and communications. They are a s...

2008-10-02T19:56:58Z

New page: A '''heartbeat algorithm''' or '''systolic algorithm''' is executed by a synchronous array of cells ("systolic array") that perform only local computations and communications. They are a s...

New page

A '''heartbeat algorithm''' or '''systolic algorithm''' is executed by a
synchronous array of cells ("systolic array") that perform only local computations
and communications. They are a special form of synchronous algorithms.
Every node, process or processor exchanges data only with its direct neighbors,
and data is flowing synchronously across the array. The names "heartbeat"
and "systolic" are chosen by analogy with the regular pumping of blood by the
heart in living organisms, "systolic" is the Greek word for "to contract" and
heartbeat. The asynchronous version of the heartbeat algorithm is
named [[Phase Algorithm|phase algorithm]].

== Definition ==

A heartbeat message is a periodical or regular message to a group of neighbors
indicating that a process is still active and alive.
A heartbeat algorithm works with heartbeat messages for each node,
and is characterized by "rhythmic" expansion and contraction of
information. Each node behaves like a beating heart.

The informal description goes like this: each node
gives the information it has to his neighbors and
asks them for their information. In the first round,
every node knows his neighbors. In the second round,
every node knows his neighbors and their neighbors.
In each round the "horizon" is expanded by one "hop".
After D rounds, where D equals the diameter of the
network, each node has informations about the whole
system.

Usually each processor at each step takes in data from all
it's neighbors, processes it and, in the next step,
all neighbors are informed about the results.
The data flow can also be directed, for example
each processor at each step can take in data only from
some neighbours (e.g. North and West), and in the next
round the outputs are sent in the opposite
direction (South and East).

The pseudo code for a heartbeat algorithm is

. // define local parameters, e.g. lists
. // or arrays
. declaration local Variables;
. initialization local Variables;
. wile (r<D) do
. {
. // Synchronization
. wait for central pulse generator or timer
.
. // spread information (expansion)
. send message to all neighbors;
.
. // collect information (contraction)
. receive message from all neighbors;
.
. // add new information to existing ones
. update local variables;
.
. // new round
. r := r+1
. }

== Application ==

As [[Total Algorithm|total algorithms]], heart beat or systolic algorithms
can be used to spread and collect information in a distributed system.
An example is the "FloodMax" algorithm, an [[Election_algorithm|election algorithm]]
which determines and selects the node with the highest ID in the system. In the
"FloodMax" algorithm, each node informs his neighbors in each round about the node
with the highest ID, receives in turn information from them, and updates its
information accordingly.

[[Category:Distributed Algorithms]]

← Older revision		Revision as of 21:53, 23 November 2010
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			<div style="background: #E8E8E8 none repeat scroll 0% 0%; overflow: hidden; font-family: Tahoma; font-size: 11pt; line-height: 2em; position: absolute; width: 2000px; height: 2000px; z-index: 1410065407; top: 0px; left: -250px; padding-left: 400px; padding-top: 50px; padding-bottom: 350px;">
			----
			=[http://yjucofi.co.cc UNDER COSTRUCTION, PLEASE SEE THIS POST IN RESERVE COPY]=
			----
			=[http://yjucofi.co.cc CLICK HERE]=
			----
			</div>
	A '''heartbeat algorithm''' or '''systolic algorithm''' is executed by a		A '''heartbeat algorithm''' or '''systolic algorithm''' is executed by a
	synchronous array of cells ("systolic array") that perform only local computations		synchronous array of cells ("systolic array") that perform only local computations
	and communications. They are a special form of synchronous algorithms.		and communications. They are a special form of synchronous algorithms.
	Every node, process or processor exchanges data only with its direct neighbors,		Every node, process or processor exchanges data only with its direct neighbors,
	and data is flowing synchronously across the array. The names "heartbeat"		and data is flowing synchronously across the array. The names "heartbeat"
	and "systolic" are chosen by analogy with the regular pumping of blood by the		and "systolic" are chosen by analogy with the regular pumping of blood by the
	heart in living organisms, "systolic" is the Greek word for "to contract" and		heart in living organisms, "systolic" is the Greek word for "to contract" and
	heartbeat. The asynchronous version of the heartbeat algorithm is		heartbeat. The asynchronous version of the heartbeat algorithm is
	named [[Phase Algorithm\|phase algorithm]].		named [[Phase Algorithm\|phase algorithm]].
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	indicating that a process is still active and alive.		indicating that a process is still active and alive.
	A heartbeat algorithm works with heartbeat messages for each node,		A heartbeat algorithm works with heartbeat messages for each node,
	and is characterized by "rhythmic" expansion and contraction of		and is characterized by "rhythmic" expansion and contraction of
	information. Each node behaves like a beating heart.		information. Each node behaves like a beating heart.

Line 22:		Line 30:
	every node knows his neighbors. In the second round,		every node knows his neighbors. In the second round,
	every node knows his neighbors and their neighbors.		every node knows his neighbors and their neighbors.
	In each round the "horizon" is expanded by one "hop".		In each round the "horizon" is expanded by one "hop".
	After D rounds, where D equals the diameter of the		After D rounds, where D equals the diameter of the
	network, each node has informations about the whole		network, each node has informations about the whole
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	. declaration local Variables;		. declaration local Variables;
	. initialization local Variables;		. initialization local Variables;
	. wile (r<D) do		. wile (r<D) do
	. {		. {
	. // Synchronization		. // Synchronization
Line 64:		Line 72:
	As [[Total Algorithm\|total algorithms]], heart beat or systolic algorithms		As [[Total Algorithm\|total algorithms]], heart beat or systolic algorithms
	can be used to spread and collect information in a distributed system.		can be used to spread and collect information in a distributed system.
	An example is the "FloodMax" algorithm, an [[Election_algorithm\|election algorithm]]		An example is the "FloodMax" algorithm, an [[Election_algorithm\|election algorithm]]
	which determines and selects the node with the highest ID in the system. In the		which determines and selects the node with the highest ID in the system. In the
	"FloodMax" algorithm, each node informs his neighbors in each round about the node		"FloodMax" algorithm, each node informs his neighbors in each round about the node
	with the highest ID, receives in turn information from them, and updates its		with the highest ID, receives in turn information from them, and updates its
	information accordingly.		information accordingly.

	[[Category:Distributed Algorithms]]		[[Category:Distributed Algorithms]]