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Questions tagged [distributed-systems]

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

105 questions with no upvoted or accepted answers
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8
votes
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
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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
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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
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83 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
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0answers
317 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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0answers
475 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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0answers
103 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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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
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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
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0answers
52 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 ...
3
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0answers
104 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
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0answers
471 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
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0answers
4k 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
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0answers
113 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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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
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0answers
69 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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0answers
29 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
27 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
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0answers
38 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
69 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
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0answers
130 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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0answers
105 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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0answers
50 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
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0answers
60 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
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0answers
63 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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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
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0answers
43 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
42 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
280 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
71 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
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
17 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
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0answers
25 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
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0answers
57 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 ...
1
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0answers
18 views

Resetting Vector clocks in distributed systems

I understand that vector clocks are preferred over lamport clocks because sometimes lamport clocks cannot account for the casuality and we use extra space to store the timestamps in the vector clocks. ...
1
vote
1answer
25 views

Input distribution in FLP Impossibility

Lemma 2 in "Impossibility of Distributed Consensus with One Faulty Process" is as follows: LEMMA 2. P has a bivalent initial configuration. They prove this by showing that the opposite assumption ...
1
vote
1answer
66 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
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0answers
18 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 ...
1
vote
0answers
65 views

A tree-like data structure with rights delegation for distributed computing

Every actor can create a root node and delegate a right to add a child node. Every node contains name of its’ creator or who added it, and value S. Sum of all values S at the same level of the tree ...
1
vote
0answers
25 views

Why in the Map Reduce Implementation, why not stream the records to the reducer (via TCP) as they are being produced by the mappers?

In the Map-Reduce implementation, the reducers start when all mappers finish their jobs. Why don't we stream the records from mappers to reducers while they are being processed instead? I think there ...
1
vote
0answers
43 views

How do distributed algorithms for shortest path finding handle negative cycles?

I am searching the web for an answer to this question, but I have only found answers for non-distributed algorithms. I am interested in this for its application to Distance Vector routing.
1
vote
0answers
25 views

Why don't RDBMS use a quorum based solution to do failover

For RDBMS viz. MySql, PostgreSql a common solution for scalability and high availability is to run a primary instance as master that is a read-write instance and one or more read replicas. If the ...
1
vote
0answers
56 views

Strong Uniform Total Order vs Weak Uniform Total Order

The definition for SUTO and WUTO is the following: Suto If some process TODelivers some message m before message mʹ, then a process TODelivers mʹonly after it has TODelivered m. And for WUTO ...
1
vote
1answer
193 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 ...
1
vote
0answers
31 views

Tendermint Consensus - Resilient up to 1/3 of Byzantine participants

Tendermint Consensus is resilient for up to 1/3 of Byzantine participants. Question: What actually happens after when the network hits the threshold of byzantine actors? Forking happens? Does ...
1
vote
0answers
40 views

Number of replicas needed for fault tolerance in state machine replication

I am trying to get my head around "State Machine Replication". I understand that it is a way to ensure resilience against failures. I have read that in order to provide fault tolerance against normal ...
1
vote
0answers
123 views

bakery algorithm, switching up the condition

I'm currently studying the Bakery Algorithm. I understand it for what it is but now I want to switch it up a bit. If we changed the < in the 2nd ...
1
vote
0answers
10 views

Where can I find practice for given atom instructions, implement ME

I'm trying to practice for my upcoming distributed systems test. My teacher said that their will be a problem where he'll give us atomic instructions and we're going to have to implement Mutual ...
1
vote
0answers
199 views

Distributing Neural Network Training World-Wide Using Blockchain?

I just finished reading a white-paper from a recent AI startup. The company, Deep Brain Chain, wants to distribute neural network training over computers worldwide, using blockchain technology. Here ...