M-TOP: Multi-Target Operator Placement of Query Graphs for Data Streams
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M-TOP: Multi-Target Operator Placementof Query Graphs for Data Streams
Nazario Cipriani, Oliver Schiller, Bernhard Mitschang
IDEAS 2011 – Lisbon, 21. September 2011
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Universität StuttgartSFB 627
Sample Scenario – Distributed Visualization Pipeline
Interpolator:Interpolates the
Velocity Field
Window Tracker:Tracks the
Window States
Fluid Solver:Calcutales theVector Field
Rendering:Project Primitives,
Rasterize Primitives
Mobile Client:
Display Images
Sources Operators Sinks
Update Orientation
Update User LocationPosition Tracker:
Tracks the Positionsof the Mobile Objects
Update Mobile Objects
Update Window States
CalculateStream Lines:Stream Lines
Calculation
CalculateStream Ribbons:Stream Ribbons
Calculation
Environment:Provides Data for
Environment
CalculateMagnitude:
Calculates theVelocity Magnitude
Distribute:Seeds the Stream
Lines StartingPositions
Desktop Computer:
Display Images
Rendering:Project Primitives,
Rasterize Primitives
Update Orientation
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Universität StuttgartSFB 627
Sample Scenario – Distributed Visualization Pipeline
Interpolator:Interpolates the
Velocity Field
Window Tracker:Tracks the
Window States
Fluid Solver:Calcutales theVector Field
Rendering:Project Primitives,
Rasterize Primitives
Mobile Client:
Display Images
Sources Operators Sinks
Update Orientation
Update User LocationPosition Tracker:
Tracks the Positionsof the Mobile Objects
Update Mobile Objects
Update Window States
CalculateStream Lines:Stream Lines
Calculation
CalculateStream Ribbons:Stream Ribbons
Calculation
Environment:Provides Data for
Environment
CalculateMagnitude:
Calculates theVelocity Magnitude
Distribute:Seeds the Stream
Lines StartingPositions
Desktop Computer:
Display Images
Rendering:Project Primitives,
Rasterize Primitives
Update Orientation
3
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Universität StuttgartSFB 627
There are More Sample Scenarios…
Navigation application considering current position of mobile objects
Online trajectory compression on mobile devices
Tourist information guide
…
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Universität StuttgartSFB 627
Operator Placement Problem
Static Data 2
Sensor1 Sensor2Static Data 1
5
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Universität StuttgartSFB 627
Operator Placement Problem
Static Data 2
Sensor1 Sensor2Static Data 1
Query Document
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Universität StuttgartSFB 627
Operator Placement Problem
Static Data 2
Sensor1 Sensor2Static Data 1
Pinned operators
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Universität StuttgartSFB 627
Operator Placement Problem
Static Data 2
Sensor1 Sensor2Static Data 1
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Universität StuttgartSFB 627
Operator Placement Problem
Static Data 2
Sensor1 Sensor2Static Data 1
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Universität StuttgartSFB 627
Operator Placement Problem
Static Data 2
Sensor1 Sensor2Static Data 1
But: Placement is NP-Complete!
Approximation!
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Universität StuttgartSFB 627
Agenda
Multi-Target Operator Placement Problem
Classification of Placement Strategies
M-TOP Approach
Evaluation
Conclusion and Future Work
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Universität StuttgartSFB 627
Customer (c) Bandwidth
> 500 kbit Cost
No costs
Customer (b) Bandwidth
> 1 Mbit Latency
< 2 s Cost
< 1 Unit
Multi-Target Operator Placement Problem – Domain-specific Requirements
Customer (a) Bandwidth
> 10 Mbit Latency
<= 500 ms
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Universität StuttgartSFB 627
Customer (c) Bandwidth
> 500 kbit Cost
No costs
Customer (b) Bandwidth
> 1 Mbit Latency
< 2 s Cost
< 1 Unit
Multi-Target Operator Placement Problem – Domain-specific Requirements
Customer (a) Bandwidth
> 10 Mbit Latency
<= 500 ms
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Multi-Target Operator Placement Problem! Different requirements for placement decision!
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Universität StuttgartSFB 627
Multi-Target Operator Placement Problem – But What to Do?
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O4O2
Q1
Q2O1
O3 S1
Bandwidth > 10 Mbit
Latency <= 500 ms
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Universität StuttgartSFB 627
Multi-Target Operator Placement Problem – But What to Do?
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Q2
O1
O2
S1
O4
O3Q1
Q2 O1
O2
S1
O4
O3Q1
? Bandwidth
> 10 Mbit Latency
<= 500 ms
O4O2
Q1
Q2O1
O3 S1
Optimize Bandwidth?
Optimize Latency?
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A Classification of Existing Placement Strategies
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Operator Placement
TargetsSystem Load Aurora, MedusaLatency SBON, Rizou et al.
single target multi target
fixed variableDecision Making Decision Making
Cost + Delay Mariposa
a priori a posterioriLatency + Bandwidth Bonfils et al.Latency + Network Load Rizou et al.
a prioriMetaheuristic Search E.g.: Tabu Search,
Sinnulated Annealing
QoS-aware Placement M-TOP
Bandwidth SAND/BorealisOperator Importance ACES
Latency + System Load Zhou et al.Processing + Transmission + Storage Ying et al.
a posteriori
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Universität StuttgartSFB 627
A Classification of Existing Placement Strategies
17
Operator Placement
TargetsSystem Load Aurora, MedusaLatency SBON, Rizou et al.
single target multi target
fixed variableDecision Making Decision Making
Cost + Delay Mariposa
a priori a posterioriLatency + Bandwidth Bonfils et al.Latency + Network Load Rizou et al.
a prioriMetaheuristic Search E.g.: Tabu Search,
Sinnulated Annealing
QoS-aware Placement M-TOP
Bandwidth SAND/BorealisOperator Importance ACES
Latency + System Load Zhou et al.Processing + Transmission + Storage Ying et al.
a posteriori
Multi-target operator placement with variable
targets and a priori decision making
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The M-TOP Approach – Target Definition
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Query graph developers provide target specifications
Example QoS-Targets specification
bottleneck condition
relative importance
rank scheme
Target – Bandwidth
(500kBit - 50% - Max)
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The M-TOP Approach – Runtime Statistics
QoS-Statistics include Bandwidth, Latency, Reliability, …
Collected during execution of operators
Node–Node QoS-statistics Describe link performance between nodes
Node–Operator QoS-statistics Describe node performance executing a certain operator
Characteristic diagram of QoS-statistics as fixed length time series Describe the expected probabilities for a certain value w.r.t. QoS-statistics Lookup returns min, avg, and max value as well as the characteristic diagram
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Operators
QoS
Nodes
Nodes
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Universität StuttgartSFB 627
The M-TOP Approach
20
Conflation
Early Prune
Graph Assembly
Ranking
Mapping
Execution
Find EdgesBetween Nodes
Rank Nodes And Edges
Map Operatorsto Nodes
Execution ofQuery Graph
MergeOperators
NodePreselection
Statistics
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The M-TOP Approach – Conflation
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Conflation
Early Prune
Graph Assembly
Ranking
Mapping
Execution
Find EdgesBetween Nodes
Rank Nodes And Edges
Map Operatorsto Nodes
Execution ofQuery Graph
MergeOperators
NodePreselection
Statistics
Conflation
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Universität StuttgartSFB 627
The M-TOP Approach – Conflation
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Conflation
Early Prune
Graph Assembly
Ranking
Mapping
Execution
Find EdgesBetween Nodes
Rank Nodes And Edges
Map Operatorsto Nodes
Execution ofQuery Graph
MergeOperators
NodePreselection
Statistics
ConflationReduce
number of operators to
place!
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Universität StuttgartSFB 627
The M-TOP Approach
23
Conflation
Early Prune
Graph Assembly
Ranking
Mapping
Execution
Find EdgesBetween Nodes
Rank Nodes And Edges
Map Operatorsto Nodes
Execution ofQuery Graph
MergeOperators
NodePreselection
Statistics
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Universität StuttgartSFB 627
The M-TOP Approach – Early Prune and Graph Assembly
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Conflation
Early Prune
Graph Assembly
Ranking
Mapping
Execution
Find EdgesBetween Nodes
Rank Nodes And Edges
Map Operatorsto Nodes
Execution ofQuery Graph
MergeOperators
NodePreselection
Statistics
Eliminated by Early Prune
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Universität StuttgartSFB 627
Execution ofQuery Graph
The M-TOP Approach – Early Prune and Graph Assembly
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Conflation
Early Prune
Graph Assembly
Ranking
Mapping
Execution
Find EdgesBetween Nodes
Rank Nodes And Edges
Map Operatorsto Nodes
MergeOperators
NodePreselection
Statistics
Eliminated by Graph Assembly
Eliminated by Early Prune
Execution ofQuery Graph
bottleneck condition relative importancerank scheme
Target – Bandwidth
(500kBit - 50% - Max)
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Universität StuttgartSFB 627
The M-TOP Approach – Early Prune and Graph Assembly
26
Conflation
Early Prune
Graph Assembly
Ranking
Mapping
Execution
Find EdgesBetween Nodes
Rank Nodes And Edges
Map Operatorsto Nodes
Execution ofQuery Graph
MergeOperators
NodePreselection
Statistics
Eliminated by Graph Assembly
Eliminated by Early Prune
Reduce number of
nodes!
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Universität StuttgartSFB 627
The M-TOP Approach
27
Conflation
Early Prune
Graph Assembly
Ranking
Mapping
Execution
Find EdgesBetween Nodes
Rank Nodes And Edges
Map Operatorsto Nodes
Execution ofQuery Graph
MergeOperators
NodePreselection
Statistics
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Universität StuttgartSFB 627
The M-TOP Approach – Ranking
28
Conflation
Early Prune
Graph Assembly
Ranking
Mapping
Execution
Find EdgesBetween Nodes
Rank Nodes And Edges
Map Operatorsto Nodes
Execution ofQuery Graph
MergeOperators
NodePreselection
Statistics
bottleneck condition
relative importance
rank scheme
Target – Bandwidth(500kBit - 50% - Max)
Rank value 0.75
Rank value 0.6
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Universität StuttgartSFB 627
The M-TOP Approach – Ranking
29
Conflation
Early Prune
Graph Assembly
Ranking
Mapping
Execution
Find EdgesBetween Nodes
Rank Nodes And Edges
Map Operatorsto Nodes
Execution ofQuery Graph
MergeOperators
NodePreselection
Statistics
bottleneck condition
relative importance
rank scheme
Target – Bandwidth(500kBit - 50% - Max)
Rank value 0.75
Rank value 0.6
Bring to front
candidates by scoring
value!
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Universität StuttgartSFB 627
The M-TOP Approach
30
Conflation
Early Prune
Graph Assembly
Ranking
Mapping
Execution
Find EdgesBetween Nodes
Rank Nodes And Edges
Map Operatorsto Nodes
Execution ofQuery Graph
MergeOperators
NodePreselection
Statistics
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The M-TOP Approach – Mapping
By modeling the Mapping Problem as CSP instance NP-formalisms are applicable
Use a meta heuristic to solve the complex problem Genetic Algorithm (GA) but also other methods (Backtracking, …) are possible
Reason: Computationally too expensive to calculate all possibilities and pick best solution
A Genetic Algorithm (GA) is inspired by the Darwinian law that the fittest individuals (or solutions) have higher probability to survive than others
E.g., fitter ones can better adapt to changing conditions
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The M-TOP Approach – Mapping as Genetic Algorithm
Loop until termination condition is true Maximum number m of iterations reached or best solution did not change
over last k steps
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Universität StuttgartSFB 627
The M-TOP Approach – Mapping as Genetic Algorithm
Loop until termination condition is true Maximum number m of iterations reached or best solution did not change
over last k steps
Step1: Assign fitness values to individuals Corresponds to the objective function for the mapping step with additional
constraints
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Universität StuttgartSFB 627
The M-TOP Approach – Mapping as Genetic Algorithm
Loop until termination condition is true Maximum number m of iterations reached or best solution did not change
over last k steps
Step1: Assign fitness values to individuals Corresponds to the objective function for the mapping step with additional
constraints
34
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Universität StuttgartSFB 627
The M-TOP Approach – Mapping as Genetic Algorithm
Loop until termination condition is true Maximum number m of iterations reached or best solution did not change
over last k steps
Step1: Assign fitness values to individuals Corresponds to the objective function for the mapping step with additional
constraints Step2: Select individuals for recombination and mutation Step3: Recombine and mutate individuals
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Loop until termination condition is true Maximum number m of iterations reached or best solution did not change
over last k steps
Step1: Assign fitness values to individuals Corresponds to the objective function for the mapping step with additional
constraints Step2: Select individuals for recombination and mutation Step3: Recombine and mutate individuals
The M-TOP Approach – Mapping as Genetic Algorithm
36
potentialrecombination points
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Universität StuttgartSFB 627
The M-TOP Approach – Mapping as Genetic Algorithm
Loop until termination condition is true Maximum number m of iterations reached or best solution did not change
over last k steps
Step1: Assign fitness values to individuals Corresponds to the objective function for the mapping step with additional
constraints Step2: Select individuals for recombination and mutation Step3: Recombine and mutate individuals Step4: Store fittest individuals, go to Step1 if term. condition is false
Return the fittest (the best) individual
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Universität StuttgartSFB 627
The M-TOP Approach – Mapping as Genetic Algorithm
Loop until termination condition is true Maximum number m of iterations reached or best solution did not change
over last k steps
Step1: Assign fitness values to individuals Corresponds to the objective function for the mapping step with additional
constraints Step2: Select individuals for recombination and mutation Step3: Recombine and mutate individuals Step4: Store fittest individuals, go to Step1 if term. condition is false
Return the fittest (the best) individual
38
Mapping
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Evaluation – Runtime Measurements
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Evaluation – Runtime Measurements – Mapping
40
Runtime:much faster than simply probing
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Evaluation – Runtime Measurements – Mapping
41
Runtime:much faster than simply probing
Objective value:approximation works well (maybe better for bigger
candidate node cardinalities)
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Evaluation – Runtime Measurements – Mapping
42
Runtime:much faster than simply probing
Objective value:approximation works well (maybe better for bigger
candidate node cardinalities)
Additive QoS:approximation and best
latency possible not far-off
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Evaluation – Runtime Measurements – Mapping
43
Runtime:much faster than simply probing
Objective value:approximation works well (maybe better for bigger
candidate node cardinalities)
Additive QoS:approximation and best
latency possible not far-off
M-TOP achieves approx. 90%-95%
of optimal solution.
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Conclusion and Future Work
Multi-target operator placement with variable targets and a priori decision making
Specify placement requirements in terms of QoS-targets Bottleneck condition, relative importance, rank scheme
To find possible solutions M-TOP adopts a meta-heuristic in form of a GA to sample the search space
Future work include Consider already running query graphs, adapt to changing conditions (e.g.,
operator migration)
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Finish… And Flowers for You!
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