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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11 views
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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26 views
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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23 views
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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1answer
29 views
“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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0answers
38 views
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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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 ...
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8 views
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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20 views
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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11 views
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 ...
2
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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 ...
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0answers
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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10 views
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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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 ...
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14 views
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 ...
2
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1answer
35 views
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. ...
0
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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 ...
0
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1answer
14 views
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 ...
0
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1answer
29 views
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 ...
0
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1answer
21 views
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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15 views
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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0answers
10 views
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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1answer
17 views
Method of communication in Distributed Systems
Why the method of communication used in DS is message passing and not shared memory ?
3
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1answer
38 views
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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18 views
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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0answers
24 views
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 ...
2
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1answer
29 views
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 ...
2
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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 ...
3
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1answer
26 views
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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1answer
81 views
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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0answers
12 views
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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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
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1answer
43 views
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. ...
4
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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 ...
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5 views
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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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 ...
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0answers
17 views
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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0answers
14 views
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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0answers
10 views
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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20 views
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
75 views
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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26 views
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 ...
1
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1answer
43 views
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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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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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 ...
0
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1answer
146 views
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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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 ...
-3
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1answer
377 views
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 ...
0
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1answer
171 views
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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1answer
44 views
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?
