Questions tagged [distributed-systems]
Questions about the challenges of solving problems with multiple cooperating but separate agents.
117
questions with no upvoted or accepted answers
8
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0answers
77 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 ...
6
votes
0answers
86 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 ...
5
votes
0answers
37 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 ...
4
votes
0answers
34 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
votes
0answers
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
votes
1answer
105 views
In the FLP Impossibility paper, why did the authors claim that e is applicable to every E in proof of lemma 3?
The paper is available here:
https://groups.csail.mit.edu/tds/papers/Lynch/jacm85.pdf
The 1st paragraph of lemma 3's proof says
In other words,if event e is applicable to config C,and E is any ...
4
votes
0answers
627 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
votes
0answers
496 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
votes
0answers
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
votes
0answers
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
votes
0answers
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
votes
0answers
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
votes
0answers
118 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 "...
3
votes
0answers
574 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,...
3
votes
0answers
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 ...
3
votes
0answers
118 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
votes
0answers
163 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 ...
3
votes
0answers
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
votes
2answers
93 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
votes
0answers
37 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 ...
2
votes
0answers
66 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
votes
0answers
20 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
votes
0answers
55 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 ...
2
votes
0answers
35 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
votes
0answers
47 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 ...
2
votes
0answers
39 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
votes
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? ...
2
votes
0answers
167 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
votes
0answers
505 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
votes
0answers
114 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
votes
0answers
56 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 ...
2
votes
0answers
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 ...
2
votes
0answers
69 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
votes
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
votes
0answers
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 ...
2
votes
0answers
45 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
votes
0answers
43 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
votes
0answers
285 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
votes
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 Ā«N request over 1 dayĀ» where N is of ...
2
votes
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 ...
1
vote
0answers
13 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 ...
1
vote
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 ...
1
vote
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 ...
1
vote
0answers
29 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 ...
1
vote
1answer
30 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 ...
1
vote
0answers
31 views
Byzantine Generals Problem - Regular Set of Neighbors
Going through Lamport's paper, I'm a little confused by the second part of the regular set of neighbors definition.
A set of nodes $\{i_1, \ldots, i_p\}$ is said to be a regular set of neighbors ...
1
vote
0answers
66 views
Byzantine Generals Problem - Oral and Signed Messages
Having just read through Lamport's paper, I was hoping someone could clarify a few things on the Oral and Signed message algorithms.
Why do we have to run $OM()$, recursively by $m$? If a majority of ...
1
vote
0answers
81 views
Paxos algorithm, accept phase
From the wiki https://en.wikipedia.org/wiki/Paxos_(computer_science)
If a Proposer receives enough Promises from a Quorum of Acceptors, it needs to set a value v to its proposal. If any Acceptors had ...
1
vote
1answer
89 views
Where were the ideas of vote, accept and commit phases originally introduced?
In the Stellar Consensus Protocol SCP, the voting procedure follows a 3 phase commit i.e. vote, accept and confirm i.e. see section 5.
Is this a novel introduction or has this been previously been ...
1
vote
0answers
22 views
Problem of making entities agree on some wavelength
I remember seeing this problem somewhere before, but don't remember what it's called and can't find it again.
It was presented as two guys having $n$ phones each that don't ring when called. Each ...
