Questions tagged [deadlocks]

In OS, a deadlock is where two or more processes are waiting indefinitely for an event that can be caused by one of the waiting processes. Deadlock is a common problem in distributed systems, parallel computing & multiprocessing systems.

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Does starvation freedom imply progress?

The above answer taken from the book https://www.amazon.com/Operating-Systems-Sibsankar-Haldar/dp/8131730220 says starvation freedom may not imply progress as processes can be deadlocked. I think ...
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Lamport's Bakery algorithm with other > relation

i'm reading an old exam and one question was: Which property of the Bakery algorithm is violated with the following change? ...
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1k views

How do modern Operating Systems detect process starvation?

So first off do the modern operating systems like windows and linux have a method for detecting starvation? if not, why? and if they do, then how are they going to detect starvation of a process? (...
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Does this state certify to be called as a deadlock?

I came across following problem: Barrier is a synchronization construct where a set of processes synchronizes globally i.e., each process in the set arrives at the barrier and waits for all others ...
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392 views

Deadlock vs "Progress" requirement of the solution to the critical section problem

I came across following problem: Consider following code: ...
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463 views

Given a program which when executed spawns two concurrent processes : semaphore X : = 0 ; Is it possible for process P1 and P2 to starve?

Given below is a program which when executed spawns two concurrent processes: ...
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Starvation and Livelock

I think Option C is false. Following is my thought process: Starvation in general mean Process is waiting indefinitely for the resource or to get scheduled etc. [A/c to Galvin Book]. So, here in this ...
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93 views

How to prove that an algorithm has no deadlock

I need to mathematically prove that this algorithm is deadlock-free: ...
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25 views

Comparing wait-signal alternatives for synchronizing two piece of programs

I came across following problem: A certain computation generates two arrays a and b such that ...
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1answer
448 views

What fraction of all combinations is guaranteed to be deadlock free?

I found this question in the exercise of Tanenbaum (operating systems): Two processes, $A$ and $B$,each need three records $1, 2, \text{ and } 3$ in a database. If $A$ asks for them in the order $...
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Resource Allocation Graph Algorithm

In the book Operating System Concepts, it is said that: A claim edge $P_i \rightarrow R_j$ indicates that process $P_i$ may request resource $R_j$ at some time in the future. [emphasis added] ...
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Is a single starved process considered deadlocked?

In regard to the critical section problem, an algorithm that switches between allowing one of two processes, P1 or P2, to complete their critical section would cause starvation for P1 if P2 stayed in ...
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two phase locking and a contest question?

In 2PL (two phase locking), what advantage(s) does the rigorous model have over the strict model? I) There is no advantage over the strict model. II) In contrast to the strict model, it ...
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205 views

Solve a basic mutex lock problem while preventing deadlock

I am solving a problem with a bridge, where you have a one way bridge with people coming from each side. To solve this problem while preventing deadlock (two people going opposite directions on the ...
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23 views

Different ways to avoid deadlocks

I am thinking of techniques that we can implement in order to avoid deadlocks in processes. While I am aware of some tactics, e.g. killing a process when we reach a deadlock, or using spooling, would ...
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Minimal number of resources such that the system is considered safe?

In a system with a single type of resource, there are 8 processes with the following maximal requirements: Process P1 P2 P3 P4 P5 P6 P7 P8 MAX 75 60 65 35 30 45 30 30 Specify the minimal value for ...
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Deadlock still occurs

Is it in in a deadlocked state? In this graph, there is a deadlock initially I think. Since P1 is holding R1 and waiting for R2; P2 is holding R2 and waiting for R1 and R3; P3 is holding R3 and ...
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1answer
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Does Dekkers solutions to critical section problem ensure progress?

I was reading concurrency control section from Operating Systems book by William Stallings. In this book, he gives three attempts by Dekker to give solution to critical section problem: Attempt 1 <...
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204 views

Is this a deadlock?

Consider we have two processes P1 and P2. There are also two semaphores M and N which are initialized to zero. Here's how they execute: ...
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83 views

What are necessity and sufficiency?

I was reading deadlock topic from Operating Systems book by Stallings. It states four pre requisites for deadlock: Mutual exclusion No preemption Hold and wait Circular wait It then have following ...
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Banker's algorithm

I have a question regarding the banker's algorithm step 2. When it says the Need[i] <= work. Need is an n * m matrix and work is a vector of length m. I want to know what Need[i] <= Work means. ...
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301 views

2 phase locking with added increment mode

Suppose that a DBMS recognizes increment as an atomic operation, in addition to the read and ...
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154 views

I have a question about resource alocation to avoid dead lock

In the code below, three processes are competing for six resources labeled A to F.How can I modify the get request in each procedure in this graph to avoid dead lock You cannot move requests ...