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Questions tagged [mutex]

A mutex ("mutual exclusion") is a mechanism to ensure integrity when the same data or resource is accessed (in particular, changed) concurrently from several threads.

A mutex ("mutual exclusion") is a mechanism to ensure integrity when the same data or resource is accessed (in particular, changed) concurrently from several threads.

Usually when the term mutex is used, it refers to a synchronisation primitive functionally identical to a binary semaphore. As OS-level synchronisation is often rather expensive due to context switching, busy-wait solutions based on atomic operations (e.g. mutex or critical section) exist.

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AppMutex with Inno Setup: Wait few seconds before prompt

Using Inno Setup together with an AppMutex works fine - when the setup is started and the mutex still exits, the user is prompted to close this application. But following question: Is there a way to tell Inno Setup to wait 2-3 seconds if the program…
ab-tools
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Which thread owns the associated mutex after pthread_cond_broadcast?

This question concerns the pthread API for Posix systems. My understanding is that when waiting for a conditional variable, or more specifically a pthread_cond_t, the flow goes something like this. // imagine the mutex is named mutex and the…
William Rosenbloom
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Pthreads- 1 lock, 2 unlocks

If I understand correctly, then foo1() fails to unlock &private_value_. As a result, foo2()'s thread_mutex_lock does not work since foo1() never released it. What are the other consequences? int main ( ... ) foo1(); foo2(); return 0; } foo1() { …
Kevin Meredith
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Where to define a mutex in a multithread program and what is the difference

I'm new to multi-threads programming and I got confused about where to declare mutex. I got the idea of mutex, lock/unlock by googling a lot. But I still don't know where I need to declare the pthread_mutex_t variable, and what's the difference.…
Xiaoli Chen
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what problems can calling std::list/vector/map/deque::empty() outside mutex scope cause?

Consider the following code snippet: thread 1: while (true) { task = fetch_task(); { lock_guard lock(my_mutex); // modify content of my_list my_list.push_back(task); } } thread 2: while (true) { if…
frans
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Increasing concurrency in producer consumer

I am solving a specific kind of producer-consumer which goes as follows - There is a buffer of size n. Consumers take items from buffer, one item at a time (By this I mean, whenever a consumer thread has access to buffer, it won't take more than…
Sashank
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Node.js - How to ensure mutual exclusion

In Node.js I have code similar to the following: function requestHandler() { expression1; // Not I/O related expression2; } The question I have is if it is possible that expression1 gets executed for request 1 and then expression1 for…
Robert Hickman
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ReleaseMutex fails in single-thread c# windows forms app

I've looked through SO for this issue, but the other instances seem to relate only to multi-threaded app issues. My app is a straightforward single-form, single-thread app and I'm just using a mutex to ensure only one instance is run on the host…
TonyLongson
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Concerning PTHREAD_MUTEX_ROBUST

According to the official doc (emphasis mine): PTHREAD_MUTEX_ROBUST If the process containing the owning thread of a robust mutex terminates while holding the mutex lock, the next thread that acquires the mutex shall be notified about the…
Lingxi
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Thread-Safe implementation of an object that deletes itself

I have an object that is called from two different threads and after it was called by both it destroys itself by "delete this". How do I implement this thread-safe? Thread-safe means that the object never destroys itself exactly one time (it must…
IanH
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Race Condition - Can Mutexes Be More Flexible?

I have a TThread object named TTestThread. When the threads are created, they make a local copy of the global configuration variables. The user is allowed to change the global configuration variables at any time, and when he does so, all threads are…
Pascal Bergeron
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Does my solution satisfy mutual exclusion requirements?

I found a solution to the mutual-exclusion problem online that has two processes P0 and P1. (Assume that the variable turn is initialized to 0) volatile int turn; Process P0: /* Other code */ while (turn != 0) { } /* Do nothing and wait. */ …
Tia
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Deadlock when reading from a stream in FUSE

My understanding of FUSE's multithreaded read cycle is something like this: .... .-> read --. / \ open ---> read ----+-> release \ / `-> read --' .... i.e., Once…
Xophmeister
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How to use std::lock_guard on a class member mutex

In the following code the bad method fails to compile, but the good method does not. Why is providing the explicit reference to this making a difference here? #include class Foo { private: std::mutex lock_; public: Foo() = default; …
maxywb
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Mutex not releasing

My c# WinForm solution contains several projects including an Admin project containing frmAdmin and a User project containing frmUser. A third project contains frmTimer that has a timer that periodically launches frmUser. I want frmTimer to not…
Frederick
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