Questions tagged [stdmutex]
44 questions
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c++ threads safety and time efficiency: why does thread with mutex check sometimes works faster than without it?
I'm beginner in threads usage in c++. I've read basics about std::thread and mutex, and it seems I understand the purpose of using mutexes.
I decided to check if threads are really so dangerous without mutexes (Well I believe books but prefer to see…
Sergey
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Is `std::shared_mutex` virtually a superset of `std::mutex`?
std::shared_mutex can provide an exclusive lock like std::mutex. Plus it extends the synchronization capabilities by allowing the parallel read-only accesses to the multiple threads.
Under the hood the number of machine instructions might be lesser…
iammilind
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std::shared_lock release() method - how to use?
Documentation on the method (https://en.cppreference.com/w/cpp/thread/shared_lock/release) sounds confusing to me:
disassociates the associated mutex without unlocking (i.e., releasing ownership of) it
I used to explore shared_lock and unique_lock…
user3714601
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2 answers
Iterating over vector in one thread while other may potentially change reference
I have a vector allow_list that is periodically updated in a thread while another serves a function that checks if a certain string is in that allow_list via:
if (std::find(allow_list->begin(), allow_list->end(), target_string) !=…
Baiqing
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Horrible scalability of std::mutex with zero contention
Even without contention, the scalability of std::mutex seems to be horrible. This is a case where every thread is guaranteed to use its own mutex. What is going on?
#include
#include
#include
void TestThread(bool…
Tyson Jacobs
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4 answers
Destructor, when object's dynamic variable is locked by mutex will not free it?
I'm trying to solve some complicated (for me at least) asynchronous scenario at once, but I think it will be better to understand more simple case.
Consider an object, that has allocated memory, carrying by variable:
#include
#include…
Ngdgvcb
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destroy std::mutex vs pthread_mutex_t
What is the difference between std::mutex and pthread_mutex_t in CPP?
What is the correct way to destroy each one of the mutex types when they are dynamically allocated as follows:
pthread_mutex_t * mutex1 = new pthread_mutex_t();
std::mutex *…
0
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1 answer
c++ mutexes that not blocks code from inside, but allow to block it from outside
I'm trying to solve the next problem:
There are two types of functions. The first type can execute from different threads simultaneously (for example - read data from container). The second one must block all threads inside first-type-function until…
AtremSh
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c++11 std::mutex locking same thread
I am studying (refreshing) C++ now.
As part of refreshing, I tried to check std::mutex behavior by me below code.
It basically trys to do 'Manual lock/unlock', 'std::lock_guard over mutex' and 'try_lock over std::mutex'.
When I refer…
gymk
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How many mutex(es) should be used in one thread
I am working on a c++ (11) project and on the main thread, I need to check the value of two variables. The value of the two variables will be set by other threads through two different callbacks. I am using two condition variables to notify changes…
Queen W
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2 answers
Correctness of using std::atomic in combination with std::mutex
I have written a shared priority queue class.
To signal to stop serving data I use method Cancel(), which sets a sign done to false and application is not allowed to write / read any data from the queue. I am not sure about using std::atomic…
Dom
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2 answers
Protecting for loop with std::mutex
I need to protect data container with std::mutex that is used in for loop like this:
for (auto it = data.begin(); it != data.end(); ++it)
{
std::cout << it->param;
...
}
I can think of several options but they are ugly like this:
{ //…
Sergey
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3 answers
Is it necessary to lock?
I met a question in leetcode. I have viewed some solutions in the discuss. But my solution is different from others because I do not use the lock in the method first. I wonder whether my code is correct. Besides, can you give me some advice about my…
Alfred
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RAII: do mutexes in a vector declared in a loop all unlock in the next iteration?
Suppose I have the following:
// ... necessary includes
class X {
struct wrapper{ std::mutex mut{}; }
std::array wrappers{};
void Y()
{
for (auto i{0u}; i < 10; ++i)
{
…
SRSR333
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