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Questions tagged [multithreading]

For questions regarding multi-threading, the ability of a computer or a program to perform work concurrently or asynchronously by utilizing multiple concurrent streams of execution (generally referred to as threads).

Multi-threading is a common model to implement SM in multi-cored machines, where threads share memory through shared variables. In this model in parallel programming a processor can create multiple threads that will be executed in parallel. Each thread has its own stack, variables and ID, considered private state. For every thread there is a unique heap shared by all, then considered shared memory.

In order to allow a volume of work to be most effectively and safely divided into multiple concurrent streams of execution, a number of critical areas need to be addressed.

  • Scheduling: ensure worker tasks are able to progress independently and effectively (e.g. deadlock/livelock avoidance)
  • Publication: ensure data altered in one thread is only visible to others as expected
  • Synchronization: ensure critical regions are protected from multiple concurrent updates causing data loss/corruption.

The underlying tenet of concurrent processing is Amdahl's law (graph). This law governs the diminishing amount of throughput that can be achieved by greater numbers of concurrent processors/cores. Therefore the overall aim of multi-threading is to minimize the amount of serial execution (exclusive locking) within any concurrent system.

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139166 questions
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How to demonstrate java multithreading visibility problems?

If variables in Java are accessed from multiple threads, one must ensure that they are safely published. This usually means using synchronizedor volatile. I have got the impression, that some of my colleagues do not take this issue seriously, since…
Joe23
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How does a single servlet handle multiple requests from client side

How does a single servlet handle multiple client requests coming in the form of user requests ? Based on the singleton design pattern I know we get a single instance of servlet created , but how does a single servlet handle millions of requests .…
shivam-shekhar
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Application threads vs Service threads

What are the advantages/disadvantages in placing a lengthy network access code in a thread in an activity or a thread in a service? How would it affect the application? I am writing a streaming audio player and from what I've read so far putting…
zerayaqob
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What is StampedLock in Java?

I am working on a Java code, I need to implement threading in it. I was going through JAVA 8 API and I come to know about Stamped Locks. Can anyone tell me why to use StampedLocks in multithreading?
Mohit
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Why is Parallel.ForEach much faster then AsParallel().ForAll() even though MSDN suggests otherwise?

I've been doing some investigation to see how we can create a multithreaded application that runs through a tree. To find how this can be implemented in the best way I've created a test application that runs through my C:\ disk and opens all…
Devedse
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std::thread error (thread not member of std)

I compiled & installed gcc4.4 using macports. When I try to compile using -> g++ -g -Wall -ansi -pthread -std=c++0x main.cpp...: #include ... std::thread t(handle); t.join(); .... The compiler returns: cserver.cpp: In member…
luis
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Spring async method called from another async method

I'm using Spring 4 and I've noticed an odd behaviour... if I'm calling an async method multiple times from a normal instance method then they are all called in different threads and finish at random times. But if I call multiple times an async…
spauny
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Thread.VolatileRead() vs Volatile.Read()

We are told to prefer Volatile.Read over Thread.VolatileRead in most cases due to the latter emitting a full-fence, and the former emitting only the relevant half-fence (e.g. acquire fence); which is more efficient. However, in my understanding,…
Xenoprimate
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What kind of behaviour causes an interrupted exception?

I'm relatively new to Threading in Java and I've noticed that everytime I use Thread.sleep() I have to catch InterrupetdException. What kind of behaviour causes this, and in simple applications where I have a monitor thread can I just Ignore the…
Omar Kooheji
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Is localStorage thread safe?

I'm curious about the possibility of damaging localStorage entry by overwriting it in two browser tabs simultaneously. Should I create a mutex for local storage? I was already thinking of such pseudo-class: LocalStorageMan.prototype.v =…
Tomáš Zato
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Atomic properties vs thread-safe in Objective-C

In most of the discussions I've read, it indicates that making a property atomic does not guarantee it to be thread-safe, it just guarantees that the value returned won't be garbage as a result of one object writing to it and another trying to read…
Doug Smith
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Redirecting stdout and stderr to a PyQt4 QTextEdit from a secondary thread

Stack overflow. Once again, I come to you in a time of dire need, teetering precariously on the brink of insanity. This question - as may be evident from the title - is an amalgamation of several other questions I have seen answered here. I have a…
araisbec
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std::thread pass by reference calls copy constructor

Well I have an issue with passing data into a thread using std::thread. I thought I understood the general semantics of copy constructors, etc. but it seems I don't quite grasp the problem. I have a simple class called Log that has hidden it's copy…
xaviersjs
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Best practice to handle orientation change: Android

I was going through various practices to handle orientation change with threads and AsyncTask. I came across following solutions: Attach-detach model : Attaching and detaching activity to threads and AsyncTask while preserving their instance.…
Gaurav Arora
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Asynchronous Delegates Vs Thread/ThreadPool?

I need to execute 3 parallel tasks and after completion of each task they should call the same function which prints out the results. I don't understand in .net why we have Asychronous calling (delegate.BeginInvoke() & delegate.EndInvoke()) as well…
claws
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