Questions tagged [distributed-systems]

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

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How to reconcile the different definitions of asynchrony?

There are 3 definitions of asynchrony that I know of: In event-based programming, asynchrony refers to the execution of tasks in a non-sequential way, which may involve creating another thread. For ...
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What are overlay & underlaying topologies in DHT?

We are covering Distributed Hash Tables in my "Networks" class and one of the subsections is about the improvements that can be made to increase the performance of the chord. Here, the ...
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In some circumstances, the choice of transactions to abort may be obvious [closed]

In some circumstances, the choice of transactions to abort may be obvious. However, in other situations, the choice may not be so clear. In such cases, we would want to abort the transactions that ...
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Test data for tasks that communicate over network

I am working on a load balancer that schedules tasks that communicate over network. I want to test its performance, but I'm struggling to find test data for it. Currently I try to extract relevant ...
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“Equality” problem in distributed computation

I recently started learning about distributed computation on graphs (not to be confused with parallel computation with threads). I have seen as a side note in a few lower bound proofs, a reference ...
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Designing of reliable multicast algorithm, regarding validity, can you deliver before multicasting

As the title says, if an algorithm delivers $m$ before multicasting $m$, does the validity property still hold? I would argue that it doesn't matter, as the purpose of validity is to ensure that the ...
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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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Ordering Multicasting in Distributed Systems

We know that Causal ordering in ordering multicasting implies FIFO ordering. But does FIFO ordering implies Casual Ordering?
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Correctness of Linearizability vs Sequential consistency in replication

I'm currently studying Sequential consistency vs linearizability: I know that SC has to be consistent with the order of how the individual client issued them, and for linearizability, it's with the ...
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Problem identifying concurrent Events

I have a number of vector timestamps and have to identify all concurrent events: I understand why (C, F) and (H,C) are concurrent events; They fulfill following condition: But shouldn't then also ...
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2answers
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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 ...
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60 views

Two Generals' Problem Definition

I've read various descriptions of the TGP, most of which seem vague or conflicting on the precise constraints of the problem. Specifically: is it always or sometimes impossible to reach consensus ...
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Dynamic replica membership in a distributed causally-consistent database

Given a distributed causally-consistent database (a replicated key-value store where writes are propagated in causal order, in the style of this paper), what are common techniques for "scaling&...
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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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Is there any guarantee in asynchronous systems?

We know that in an asynchronous system, no assumptions about process execution speeds or message delivery times are made. My question is: can we present any guarantee in asynchronous systems? Some ...
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Averaging a list of variances

In a setting where I have n clients each owns a subset of the dataset, each computes the mean and variance on his data and send them to the server. The server would average all means and variances. ...
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1answer
21 views

How does random number probabilities work in distributed systems?

Let's say I have a code which does coin toss at 25% win probability. If I run this code n number of times in the same system it will yield ~25% win. If I run this code on n devices (once each) will ...
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1answer
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What is the relation between a web server and a local file serve in distributed systems?

I am learning distributed systems ( although I am an Electrical engineer ) using the book distributed systems concepts and design. The author says that "A web server is often a client of a local ...
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How does Lamport imply anomalous behavior is impossible given these constraints?

Lamport's paper: Time, Clocks, and the ordering of Events in a Distributed System Anomalous behavior occurs because Lamport's logical clocks are not enough to guarantee that the total ordering of ...
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Why does the converse of the clock condition imply that any two concurrent events occur at the same time?

In Lamport's paper, Time, Clocks, and the ordering of Events in a Distributed System he says that the converse of the clock condition does not hold and if it did, we could expect concurrent events to ...
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MMOGs as an example of distributed systems

In the book "Operating System Concepts and Principles" , the authors mentions massively multiplayer online games as an example of Distributed Systems. They mention that as an example of ...
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Synchronization in Distributed Systems

If there is no global clock in Distributed systems , then what is the solution for synchronization in DS ? Also , no global clock in DS is a direct consequence of the fact that the only communication ...
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Method of communication in Distributed Systems

Why the method of communication used in DS is message passing and not shared memory ?
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What is a distributed algorithm for generating random “private” pair-matchings?

Say you have 2N named peers (agents) able to address each other by their name and communicate freely among them. What distributed algorithm could they use in order to randomly pair up? The final ...
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Distributed Serializable Snapshot Isolation

I was wondering if there is any research on distributed transaction algorithms for Serializable Snapshot Isolation. I found Binnig, C. et al.: Distributed snapshot isolation: global transactions pay ...
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Why is shared register's consensus number 1?

I'm trying to understand the consensus number concept. It is trivially clear that a shared register doesn't create any problem when there is only one thread using it. By why does its consensus number ...
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Leader Election: Every bit-reversal ring is $\frac{1}{2}$-symmetric

I have a proof that I need help with. Like the title says, the theorem is that every bit-reversal ring is $\frac{1}{2}$-symmetric. The theorem is for Leader Election algorithm in synchronous ring. The ...
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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 ...
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Randomly assign n elements to n agents such that each agent only knows its own element

Problem I'm working on an app that involves shuffling and distributing playing cards to players. As a challenge, I tried to solve this problem in a way that doesn't require a trusted intermediary. In ...
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Distributed predicate computation on event stream

My question is actually a request for papers, articles, texts or books on the problem that I'm trying to solve on my work. I'm working on a program that computes a predicate value (true or false) for ...
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Why does Chord maintain a finger table instead of entire membership list (using SWIM)?

Chord uses a finger table for querying, and it takes $O(\log n)$ to get the result. Why not maintain the entire membership list and get result in $O(1)$?
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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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1answer
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Confused between 2 phase locking and 2 phase commit

I understand that both algorithms are very different, but what I don't understand is whether they achieve the same thing in the end. 2PC is for atomic commits and 2PL is for serializable isolation. ...
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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 ...
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What is the current definition for HPC systems - do they include both GPUs and MIMD Supercomputers?

I have seen several definitions across the internet and this question still bugs me.
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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 ...
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Count nodes with more than 3 neighbours in distributed computing, initiating by one site

I have an algorithm that visit all the nodes on a graph in distributed computing , the initiator is one site only , I want to change it so that the initiator can in the end of the execution know the ...
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What are the advantages of NHSX centralised protocol for Contact Tracing?

Apple and Google have published a protocol for privacy-presercing contact tracing - https://www.apple.com/covid19/contacttracing/ They use a decentralised approach where the 'matching' process take ...
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A single Paxos instance deciding on different values

I have recently been taught about the Paxos consensus protocol in my university's distributed systems course. There is a particular case that I find troubling: Suppose there are two proposers P1 and ...
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Request committed by only some non-faulty nodes in PBFT

I have recently learned about the protocol described in the paper titled "Practical Byzantine Fault Tolerance", as part of my university course on distributed systems. There was one example ...
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1answer
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Why is two-phase commit better than naive master-slave replication?

In the context of a distributed database, I'm trying to understand why 2PC (as described in e.g. https://www.cs.princeton.edu/courses/archive/fall16/cos418/docs/L6-2pc.pdf) is better than the ...
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Optimize Max-flood algorithms bounds

In distributed algorithms, The Max Flood algorithms finds the leader in a network of processes In O(diam) time and with |E|*diam ...
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Why is a threshold determined for Byzantine Fault Tolerance of an “Asynchronous” network? (where it cannot tolerate even one faulty node)

In following answer (LINK: https://bitcoin.stackexchange.com/a/58908/41513), it has been shown that for Asynchronous Byzantine Agreement: "we cannot tolerate 1/3 or more of the nodes being ...
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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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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
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Why aren’t distributed computing and/or GPU considered non-deterministic Turing machines if they can run multiple jobs at once?

So we know a nondeterministic Turing machine (NTM) is just a theoretical model of computation. They are used in thought experiments to examine the abilities and limitations of computers. Commonly used ...
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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 ...
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What is the difference between masking and tolerating failures?

Distributed Systems 5ed by Coulouris says on p21-22 1.5.5 Failure handling Detecting failures: Some failures can be detected. For example, checksums can be used to detect corrupted data in a ...
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Do arbitrary/Byzantine failures include omission failures and timing failures?

Distributed Systems 5ed by Coulouris says on p68 2.4.2 Failure Models Omission Failures ... Arbitrary Failures The term arbitrary or Byzantine failure is used to describe the worst ...
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How to convert a centralized algorithm to a distributed algorithm?

Is there any algorithm or procedure to convert a centralized algorithm to a distributed algorithm? Is there any theoretical result or relevant complexity analysis?

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