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How do threads aid in execution of a program?

Firstly this is not a question about programming. A book I am reading on C programming explains briefly the steps of execution of a C program after its compilation. It states the following, To be ...
1 vote
2 answers
260 views

Multi-threading : N cores = N times one core?

This question is about modern CPU architectures and multi-threading. I'm mainly interested in personal computers or servers having 2, 4, 8, 16... cores like for example an Intel core i7. I mean not a ...
0 votes
2 answers
236 views

What are the examples of multi-threading in a web server?

So I’ve been reading about multi-threading these past few days. Can you give me a real life example where the multi-threading might be used in a REST API web server?
0 votes
1 answer
75 views

How to find optimum number of cpu cores for a workload

Following bar graph shows maximum percentage cpu utilization of F16sv2 (16vcpu &32GB) azure virtual machine in last 30 days. Only sometimes CPU usage goes more than 60 percentage. How to find the ...
0 votes
1 answer
83 views

Why is it not a good idea to branch a thread outside of a parallel region while other threads are still executing?

Say I have $n$ threads executing in a parallel region and one of them leaves the parallel region when others are still continuing to execute in the parallel region. Why this is a $BAD$ idea? For ...
0 votes
1 answer
27 views

Thread safety due to no runtime allocation of memory, why?

I was watching a presentation related to the MuJoCo simulator (and other topics which were more relevant for the presentation itself) and at one moment in the presentation it is mentioned that MuJoCo ...
2 votes
2 answers
145 views

Would it be possible to run destructors when aborting a thread?

I had a discussion with a C++ developer on whether aborting a thread causes memory leaks. His opinion on how aborting a thread works was all destructors of the stack objects of the thread to abort ...
0 votes
1 answer
362 views

Two-Level Threading Model

In multithreading models, we have a two-level model in which we multiplexes many user-level threads to a smaller or equal number of kernel threads but also allows a user-level thread to be bound to a ...
0 votes
1 answer
52 views

Threads and its priority in Java

I was experimenting with the concept of threading in java, we have a method setPriority, using which we can set thread priority. In official documentation it is given as below, But while seeing in ...
3 votes
2 answers
164 views

Race condition, my doubt on Peterson's algorithm vs. C

I have seen this C code showing an implentation of Peterson's Critical Section algorithm. It is obviously skeletal and hardwired for two threads but the logic is supposed to be correct in detail. ...
1 vote
1 answer
258 views

Is it correct to say that CPUs only compute threads?

As a newcomer to the field of parallel computation, is it accurate to say that CPUs are essentially "thread" calculators? My current understanding is that a "process" is made up of ...
0 votes
3 answers
489 views

What is the minimum and maximum value of Counter when the two threads are executed concurrently?

I'm studying for an exam and have run into a problem that I do not understand. The main program starts two threads that execute the following program concurrently, whenever both threads terminate the ...
2 votes
2 answers
599 views

Why does python's threading library use OS level threads when it can't achieve parallelism?

I was surprised to hear that the threading module from python uses OS level threads. From what I know, OS level threads are more expensive (but can achieve parallelism) meanwhile green threads are ...
1 vote
0 answers
33 views

Thread wait state due to a cache miss

I know that a thread in a "running" state is put in a "wait" state if the thread itself needs I/O operation. Now I'm asking if even a cache miss implies that a thread is put in a &...
2 votes
1 answer
57 views

Are there any operating systems that utilize only user threads?

We're going over threading models in my freshman CS class. Are there any examples of operating systems that use exclusively user threads (N:1)? It looks like 1:1 is far and away the most common model ...
3 votes
1 answer
2k views

What are the differences between Earliest Deadline First (EDF) and Earliest Due Date (EDD)?

From my understanding, the EDF (Earliest Deadline First) rule is essentially an iterative "version" of the EDD (Earliest Due Date) rule, which allows for preemption. At every point in time, ...
0 votes
1 answer
62 views

Reader / writer locking algorithm

I'm pretty sure there's a textbook solution to this problem, but I haven't figured it out. I have fixed-size blocks of data arranged in a sequence: block 0, block 1, etc.. There are reader threads ...
1 vote
1 answer
402 views

Deadlocks: Why if 2 threads are waiting for a lock from each other results in a deadlock?

I am confused as to why 2 threads waiting for a lock from each other will result in a deadlock. Let's say I have a Thread 1 that needs to execute contents in Lock 1 and then Lock 2 and a Thread 2 that ...
0 votes
1 answer
107 views

What is the need for Kernel threads?

I'm a bit confused about kernel-threads, I searched a lot at the Internet, SOF and here but found very diverse and conflict answers. What is the need for Kernel threads? Are they threads that are only ...
0 votes
2 answers
1k views

concurrency in multiple core

I know the basic definition between parallelism and concurrency. But there is not much information about concurrency in multiple core. what is the difference between concurrency in single-core vs ...
0 votes
1 answer
59 views

Which overhead is smaller - function call or passing variables between processes?

the question is related to networking frameworks; callback-based approach requires you to call a callback function every time you receive a new data packet; this is not a good approach for high-load ...
1 vote
2 answers
228 views

How could i create a multi-threading system in a kernel?

Im trying to figure out if there's an assembler instructions or a bios intruction to get multi-threading in a kernel. In the case that doesn't exist that, how could i set muti-threading in a kernel?
1 vote
3 answers
225 views

concurrency vs parallelism

I am so confused between concurrency vs parallelism in multi-core processors. If a concurrent process has many threads and if the processor is multi-core then can each thread run on multiple cores? If ...
0 votes
1 answer
47 views

Running an application that needs 6 threads on dual core processor

If a dual core processor have 4 threads, then what will happen if i run an application which uses more than 4 threads? And just to make sure i'm understanding what are threads in a cpu, when an ...
0 votes
1 answer
253 views

Analyzing parallel performance question

I was reviewing for my CS class and came across this question and answer combo that didn't have any explanation why it was correct. I'm confused on how they got the answer: We have a system to which ...
1 vote
1 answer
367 views

OS: Are User-level threads and software threads (and also kernel-level threads and hardware threads) the same?

I am referencing the Book Fundamentals of Computer Algorithms" by Ellis Horowitz et al. At the part which they talk about multi-threading models, user-level and kernel-level thread are introduced....
10 votes
1 answer
568 views

Why using Hyper-threading can lead to performance degradation

I have read it at various places like this, that Hyper-threading leads to performance degradation. I am unable to get why or how hyper-threading leads to degradation. Why it is so that even when Hyper-...
5 votes
2 answers
1k views

Why do OS locks require hardware support?

I just read the chapter on locks in the book Operating Systems: Three Easy Pieces, and it discusses an implementation of locks (see in Figure 28.9) that involves a test-and-set hardware instruction. ...
3 votes
1 answer
4k views

User level threads are transparent to the kernel?

Find whether given statement True or False? Explain. User level threads are transparent to the kernel? My attempt : False. Since, user level threads are managed by a user level library however, they ...
1 vote
2 answers
117 views

Can User Level Thread read/write Kernel thread?

As far as I read in a OS text book (Operating Systems by Silberschatz) Kernel mode is for privileged task, so it it true to claim that "User Level Thread can read/write Kernel threads" ? ...
0 votes
1 answer
560 views

Does every thread have its main function?

Does every thread have its own main function? I know that its have its own stack, but what about main function (not necessarily a function which called main). For example, when creating a thread, we ...
1 vote
0 answers
30 views

Race Condition in Mesa Monitor

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1 vote
1 answer
171 views

How to trigger a thread to start working using semaphore?

How to trigger a thread to start working using semaphore? I have find a lot of explanation about thread and semaphore but i still don't understand, any help please
0 votes
1 answer
239 views

Thread - contention vs race

The terms contention and race are used interchangeably when it comes to thread's state(at critical section). Are they same?
34 votes
5 answers
70k views

What threads share in general?

Well this is general question. And if anyone want to make it implementation specific then I will prefer Unix related stuff. But first need to know following problems in generality: I read single ...
0 votes
0 answers
14 views

parallelized data structure

I'm searching a data structure that supports O(1) concurrent insertions (thread number is known in advance) and iteration over its elements (insertion order doesn't need to be preserved). While one ...
5 votes
2 answers
642 views

Why the most dominant programming languages didn't follow CSP thread model?

I was trying to ask this question in StackOverflow, but later realized that this question is more relevant to general computer science, not specific engineering problems. If you think it's not, please ...
0 votes
1 answer
60 views

Reason for thread pooling

Can someone explain what is the reason for thread-pooling in Linux, even if the threads are light to create and destroy??
2 votes
1 answer
61 views

How does a dual core microprocessors run so many programs?

I have a laptop with Intel dual core and it runs, the OS windows, and many application from Opera, age of empires, word, excel etc open at once just fine. If it only has 2 cores, how can so many ...
3 votes
1 answer
1k views

What should be the minimum value when the two threads are executed concurrently

int count=0; void *thfunc() { int ctr=0; for(ctr=0;ctr<100;ctr++) count++; } If *thfunc() is executed by two threads concurrently in a uniprocessor ...
0 votes
0 answers
241 views

Can many threads run in a parallel in many-to-one model?

The book I am reading suggests that in a many-to-one multi-threading model, the threads are unable to run in parallel in a multi-core system. I am thinking this is not the case because if we have many-...
11 votes
3 answers
5k views

Why are most mutex implementations unfair?

My understanding is that most popular implementations of a mutex (e.g. std::mutex in C++) do not guarantee fairness -- that is, they do not guarantee that in instances of contention, the lock will be ...
-2 votes
1 answer
62 views

Does this lock have a name (related to reader-writer lock)

The object can be locked two different ways, where if the lock is entered the same way a second time, the lock is recursive, but if it's entered the other way, it blocks. Like a reader-writer lock, ...
2 votes
0 answers
34 views

What does it mean by "consistent view of memory" in lock-free dequeue implementation?

I am currently reading this paper by Chales-Lev. This paper explain an implementation of work-stealing dequeue. The part where I don't understand is in the implementation of steal operation. ...
1 vote
0 answers
27 views

Parallel Thread Processing Variable Question

if there is a better stack exchange suited for this question please inform me. say you have a thread that is constantly checking the state of a variable in 2 ms intervals ...
1 vote
1 answer
656 views

Why is there no one to many Multithreading Model?

I am studying various multi-threading models. Here the user threads are mapped to Kernel Threads. They are - ...
0 votes
1 answer
21 views

multithreading - duration of jobs

" How long will it take for 2 jobs to complete if they're running in parallel, knowing that both have a total of 20 minutes of CPU usage time and 50% IO" I calculated the CPU usage: ...
0 votes
1 answer
52 views

Threads and Operating System

In a computer, the processor executes different threads and changes between them, the operating system is a program at the end that it´s being executed by the processor, there exists the posibility ...
1 vote
1 answer
822 views

How can context switch affect the modification of a variable?

float myTotalAmount=0; void update(float amt){ myTotalAmount+= amt; } Task A called update(10); Calculated ...
0 votes
2 answers
649 views

Why are threads called the unit of dispatch?

Threads called the "unit of dispatch" but what does that mean? I was looking over the web and two operating systems books but I can't find the answer. It seems that processes are defined by two ...