Questions tagged [distributed-systems]

Questions about the challenges of solving problems with multiple cooperating but separate agents.

129 questions with no upvoted or accepted answers
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8
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0answers
80 views

Distributed Storage for Access and Preservation

My organization wants to maintain multiple copies of data in order to preserve access in the case of localized disasters as well as for the purpose of long term preservation. Are there accepted formal ...
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87 views

What is 2g-precedence?

I am currently reading a couple of papers about event processing. In the context of ordering events, "2g-precedence" is frequently mentioned. I don't know what it is, and I cannot find much ...
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38 views

Uni-directional synchronization and locking issues

Suppose there are two databases, $D_1$ and $D_2$. Let's further assume $D_1$ is always up and $D_2$ can be down sometimes. When it goes up again, it has to restart. $D_1$ is filled by say a dozen ...
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35 views

What are some advanced background topics I'll need for distributed systems and networks research?

I am a new graduate student in Computer Science who would like to be able to read and understand modern and new distributed systems research papers. My current background / courses and understanding ...
4
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72 views

What distributed consensus algorithms don't rely on a time source?

I'm looking for information about distributed consensus algorithms that: maintain a consistent transaction log across all healthy nodes have similar high-availability properties to Paxos (i.e. not ...
4
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704 views

Even distribution algorithm

Right now I am working on a distributed system that sends messages from single source to many nodes. It is necessary that certain messages are sent to the same node to ensure order of processing. ...
4
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519 views

Is there any theory behind GraphQL?

GraphQL is a query language for your API, and a server-side runtime for executing queries by using a type system you define for your data. Source: http://graphql.org/learn/ So GraphQL allows a ...
4
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56 views

How to realize a distributed queue with unreliable participants?

I want to build an application that relies on a distributed queue with participants in a decentralized (peer-to-peer) network. The participants cannot be relied on to correctly follow a protocol. I ...
4
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104 views

Optimal schedule for broadcasting a file in a complete graph with overheads

I am trying to solve the following problem and despite having performed quite extensive literature review, I do not seem to find any similar problem or technique that would be useful here. PROBLEM ...
4
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62 views

Extending the causal memory model to wide-area distributed storage systems

In the seminal paper "Causal memory: definitions, implementations, and programming", distributed causal memory is defined to ensures that all the processes in a system agree on the relative ordering ...
3
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46 views

Why does the proposer sends an accept request with the same value it got from the acceptor?

In the second phase of the paxos algorithm, the proposer issues an accept request with the number n and the value v it got from ...
3
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122 views

What are the theoretical and practical contributions of Multiagent Systems to science?

Speaking about multiagent systems (MAS) is about as fuzzy as talking about artificial intelligence systems (AI). They are in essence the distributed counterpart of AI. While there are no so-called "...
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620 views

How to generate globally unique timestamps for transactions in distributed database systems?

According the paper [1] (Section 4), timestamp ordering (T/O) is a technique whereby a serialization order is selected a priori and transaction execution is forced to obey this order. In the following,...
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5k views

totally ordered multicast with Lamport timestamp

I'm studying Distributed Systems and synchronization and I didn't catch this solution of totally ordered multicast with Lamport timestamps. I read that it doesn't need ack to deliver a message to the ...
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123 views

Why does a prepare message wants a promise that an acceptor is never to accept a proposal numbered less than its propose sequence value? (Paxos)

I was studying Paxos from: http://research.microsoft.com/en-us/um/people/lamport/pubs/paxos-simple.pdf Recall that Paxos is a distributed system algorithm with the goal that the processes ...
3
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164 views

Proof of message complexity on the network

I try to provide a strict and mathematical rigorous proof to the following problem in Distributed Algorithms. Prove or make a contradiction: if to vertices $a$ and $b$ on the network $G$ are located ...
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71 views

How is amorphous computing different from spatial computing?

Surely spatial computing and amorphous computing share similarities and overlap. Is spatial computing a subset of amorphous computing? How are the two different?
2
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21 views

Distributed transaction problem

Let's suppose there are two banks, Bank A and Bank B. A transaction needs to happen that transfers money from an account in Bank A to an account in Bank B. Bank A and Bank B have separate banking ...
2
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2answers
131 views

Ordering of operations in a DAG of git commits

Context: I'm looking for a better state resolution algorithm for https://github.com/MichaelMure/git-bug Summary of the current algorithm and shortcomings git-bug is a distributed bug-tracker that ...
2
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53 views

Using vector clocks vs. directed acyclic graph for causality detection in distributed systems

I'm trying to understand how vector clocks compare to DAGs for causality detection in a distributed system. When trying to detect causality relations in a distributed system, a very commonly proposed ...
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82 views

Why is the 'Integrity' property required in consensus protocols?

Formally a consensus protocol must satisfy the following three properties: Termination Eventually, every correct process decides some value. Integrity If all the correct processes proposed the same ...
2
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24 views

Finding the timestamps of processes implementing Lamport's clocks

I have been asked this question, but don't know how to go about answering it. Three process, which are implementing Lamport's clocks, are running and a lot of events are taking, place including some ...
2
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0answers
64 views

Leader election in synchronous ring with unreliable communication channels

As a part of my Distributed Systems course I am required to provide an algorithm that is able to elect a leader in a synchronous bidirectional ring, where every message that is sent may be lost (lets ...
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36 views

Distributed algorithms for finding n largest elements

It's easy to come up with a simple distributed algorithms for finding the maximum element in a set (totally ordered): Divide and conquer. There are a few publications that present algorithms for ...
2
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0answers
54 views

Distributed Computing: Persistent Data Structures in Functional Programming versus Wait-Free Data Structures

Persistent (aka immutable) data structures in functional programming sidestep issues of shared memory mutual exclusion, and thus also issues such as data races that arise and which may be difficult to ...
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40 views

Algorithms / heuristics for a distributed sorting problem

The setting: There's a cluster of $k$ computers (= nodes). For simplicity, assume their hardware is identical. The network topology can be complicated, but let's simplify and assume it's a clique ...
2
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0answers
75 views

Why is a primary node needed in pBFT algorithm for consensus?

Why is primary needed in pBFT algo? Since many issues of viewchange etc. come up because primary may be faulty - is it possible to have a version of pBFT which doesn't have nodes assigned as primary? ...
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176 views

Byzantine generals (n=3, m=1)

Leslie Lamport describes a algorithm to come to consensus for the case for n>3*m, there m is the number of traitors in ...
2
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605 views

How to compare distributed systems and big data

Are there scientific papers that compare distributed systems and big data processing systems? Big data processing systems can be batch processing systems or streaming big data processing systems. A ...
2
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0answers
117 views

Are Synchronous Message Order and Total Message Order separate concepts?

I am currently studying this book on distributed systems. In the chapter on message ordering the authors appear to use the term total message ordering and synchronous message ordering interchangeably. ...
2
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57 views

Auction website with Paxos consensus algorithm

As a project, I'm trying to construct a P2P auction web application with paxos in a high latency environment. The idea is that each user visiting the website will keep a small log file with the ...
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61 views

Distributed consensus feasibility from graph structure

Consider a consensus process in which participants Initially take a position Receive positions only from their neighbors Accept a new position that is a super-majority of neighbors positions. Under ...
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0answers
72 views

What is the largest number of Byzantine failures that can be tolerated in an $m$-dimensional hypercube for the consensus problem?

We are given a system with $n$ nodes which have been arranged into the topology of a hypercube of $m$ dimensions. I would like to derive a tight bound on the maximum number of Byzantine failures that ...
2
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0answers
61 views

Floating output/making a non-self stabilizing algorithm self stabilizing

So we're using this book by Shlomi Dolev on self-stabilization in class. Not being from a theretical CS background, I think the book is rather terse. Most of it is fine but there's this section on "...
2
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53 views

Find the size of the maximum cycle in a MPS

Consider the following problem to be solved in a distributed context: Find for each processor the size of the biggest cycle of which it is member. My algorithm is the following (for synchronous ...
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50 views

Distributed push relabel with changing graph topology

There is at least one (1) distributed version propsosed for the push-relabel maximum-flow algorithm. I wonder if and how this algorithm can cope with nodes leaving or enterig the graph during runtime. ...
2
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0answers
46 views

Polylogarithmic value-bounded concurrent data structures such as max register, counter, and monotone circuit

While reading the research paper Polylogarithmic Concurrent Data Structures from Monotone Circuits [@JACM'2012] by James Aspnes, Hagit Attiya, and Keren Censor-Hillel, I am not sure about some points ...
2
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0answers
286 views

Efficiently estimating latency quantiles of a distributed system

I'm building a load test harness for a distributed system. Currently I'm using the "Cormode, Korn, Muthukrishnan, and Srivastava" method to estimate latency quantiles of system responses. I'm now ...
2
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0answers
72 views

Throughput measure

I have to implement a limitation algorithm in order to avoid to reach a throughput limit imposed by the service I'm interacting with. The limit is specified as «N request over 1 day» where N is of ...
2
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0answers
1k views

k-Trees Graph Coloring

There is an exercise in Distributed Algorithm I have some difficulties to solve. There are few ideas, however nothing useful at the time. I will appreciate any help with it. Graph $G$ is a $k$-tree ...
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0answers
265 views

How is this example sequentially consistent but not linearizable?

Background information that I know(But not understand with examples, I will be glad if you could explain it to me with examples) A replicated service is said to be linearizable if for any executin ...
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0answers
11 views

Distributed Graph Consensus to fit a distribution?

$G$ is a strongly connected graph with nodes $V$ and edges $E$. Each node $v_i$ receives a sample $x_i$ from a Gaussian $\mathcal{N}(\mu,\sigma^2)$ with unknown mean and variance. The objective is for ...
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0answers
31 views

What is the difference between Swarm intelligence and Multiagentsystems?

Swarm intelligence and Multiagent systems are both a part of Distributed AI. Multiagent systems describe a system with agents, which communicate with each other. Swarm intelligence describes systems, ...
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19 views

Really confused about the chord algorithm

I'm looking at the pseudocode for chord algorithm here: ...
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0answers
48 views

Can old hardware be practically useful for CS problems of modern day?

Thinking about specific settings on WorldBuilding.SE, it turns out I need help from people who are more in touch with CS and Clusters. For those who curious about how it started, backstory here, ...
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0answers
14 views

Why is it considered hard to maintain strong consistency in a distributed system?

Why can't you just use strongly consistent reads for all your DB reads, with retries on 500 responses? According to CAP theorem increasing consistency should probably lower availability, but can't the ...
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0answers
19 views

Number of referee nodes required in distributed leader election algorithm

I know the reason as to why $O(\sqrt{n\log n})$ referee nodes are required. What I don't understand is how to arrive at that value, when I have $7\log n$ candidate nodes. Please forgive me if this is ...
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0answers
17 views

Arbitrary fault abstraction in 'Reliable and Secure Distributed Programming'

In the book by Cachin, Guerraoui, Rodrigues they discuss an arbitrary fault abstraction. It seems to me that this abstraction does not include crashes in its behavior. I think this because they ...
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33 views

What are the correlation between Actor model and Reactive Programming

Could anyone explain the difference/relation between the Actor model and Reactive programming? It seems that they are located at different levels of abstraction - one can design the interaction ...
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1answer
35 views

Implementing reliable pairwise average in distributed systems

Consider an asynchronous and unreliable distributed system. Each node has a value. Suppose that p and q are two neighbor nodes of the system (p_val and q_val are the values of p and q respectively). p ...