A Survey of Task Allocation and Load Balancing in Distributed System
Part 1. Overview on Distributed Systems
the general characteristics of real distributed system
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lack of global control unit
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reason:
large-scale
dynamic
hetergeneous
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distribution and sharing of resources
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resource :
data
processor
computational capacity
disk storage
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resource management
placement
provision
discovery
negotiation
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openness and unreliability of systems
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heterogeneous nodes
node in different organization has different property
compete for critical resource
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constraints of network structures
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node communicate with
neighbouring nodes -- directly
non-neighbouring nodes -- be relayed by intermediate node
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encounter the following situation
the tasks may be implemented by negotiation among nodes without a central control
the tasks are always implements by accessing required resources distributed in the networks
the tasks may be implemeted unreliably
the tasks performed by heterogenerous nodes may vary significantly and compete for critical resources
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the performance of tasks may be influenced significantly by network structures
resource access performance
coordination performance
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typical problems occur during the task allocation and load balancing
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control models
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totally centralized control model -- difficult to implement
large , dynamic , lack global control unit
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totally decentralized control model
require relative high computational costs from nodes, which place heavy loads on large systems and make the task allocation processes difficult to control effectively
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resource optimization
many models of task allocation and load balancing are implemented based on the optimization of accessibility of required resource
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example : 2 situation
a node has plentiful resource, it has high resource accessbility
a node doesn't have plentiful resource, but it obtains enough resource from other node easily, it can also be allocated many tasks.
in a word, consider node's own resource and contextual resource
reliablitily
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coordination among heterogenerous nodes
fact:hetergeneous nodes don't cooperate in making decisions while they execute tasks
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questions:
how to make noncooperative nodes coordinate
how to incentivize nodes to contribute their resource
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considering network structures
communication and interaction of nodes are constrained by the network structures
objectives of task allocation in existing studies
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response time
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2 types
total response time
mean response time
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makespan
time of reansfer tasks to different nodes
waiting time of tasks at node
time for accessing resource
time for communicating resource
time for processing
throughput
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raliability
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2 types
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node-related reliability
source
computation
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path-related reliability
communication path
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Part 2. Control Model in Task Allocation and Load Balancing
Centralized Control Model
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central controller
know the status information of the entire system in real time
make all decisions.
may become the bottleneck
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Distributed Control Model
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market-based approaches
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game theory
a game theory pricing model
a game theory framework for obtaining user-optimal load balancing scheme
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algorithm based on the strcuture of the Nash equilibrium
achieve of advantage of distributed structure
low complexity
optimality of allocation for each user
formulate the load balancing problem as a non-cooperative game among users
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auctions
a decentralized market protocol for task allocation among nodes that contend for sacrce resource, where node trade tasks and resource at price determined by an auction protocol
a continuous double auction method for grid resource in which resources are considered as provider agents, and users are considered as consumer agents
consensus-based auction
a metaschedular based on the double auction mechanism
contract mechanisms
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society-based approaches
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strategy diffusion
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denote:
the large scale of strategy penetrations of certain agents on other agents
negotiation between neighbouring nodes for tasks can be described as a diffusion process
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advantage
each node only knows the information of neighbouring nodes and global optimal result can be achieved finally
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coalition formation
a coalition is a alliance among individuals, in which individuals coopertae in joint action
a task allocation scheme via self-roganizing swarm coalitions for distributed mobile sensor network coverage, which uses the concepts of ant behavoir to self-regulate
community-aware task allocation model for social network systems where a node's coopertaion domain is constrained in a community and each node can negotiation only with its intracommunity member nodes
agent-based decentralized task allocation mechanism. An agent will be aotumatically dispatched to ask immediately after the task is randomly submitted to a node.
multiagent-based load balancing model where each agent has a credit value. The agent with low credit value is migrated to a ralatively lightly loaded workstation
group mechanisms
Mathhew effect
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agent-based approaches
other approaches
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Hybrid Control Model
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Future Research Directions
how to customize control model
how to coordinate the different control models of different subsystems
self-adaptation and evolution of control models for dynamic distributed systems
Part 3. Resource Optimization in Task Allocation And Load Balancing
taks allocation often means allocating tasks to resources
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Self-Owned Resource-Based Optimization
implemented based on nodes' self-owned resource statuses
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Contextual Resource-Based Optimization
implemented based on not only nodes' self-ownded resource statuses but alse their contextual resource statuses
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approach
if a node's contextual nodes have richer experiences of executing tasks, the node may have higher access to the resources even if it seldom accessed the resources by itself
contextually-experienced nodes recived more new tasks than less contextually-experienced nodes
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future research
predict resource access
resource optimization scheme should adapt to dynamic change of resource distribution
Part 4. Reliability in Task Allocation And Load Balancing
Redundancy-Based Approaches
redundancy of resources
redundancy of tasks
Non-Redundancy-Based Approaches
optimization mechanisms for reliability
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trust-or reputation-based approaches
trust-based approaches
reputation-based approaches
Part 5. Coordination Among Hetergeneous Nodes in Task Allocation And Load Balancing
game theory-based approaches
other approaches
Part 6. Considering Network Structures in Task Allocation And Load Balancing
physical communication networks
virtual interaction networks
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