Back to General and Gameplay Programming

Are mutexes really fool-proof?

Alexandr Zaš?itnikov · 2014-01-28T00:43:07

Take a look at the following code. Is it theoreticzally possible for two CPU cores to read the value of Mutex::Locked at the exact same time, both assuming the mutex is unlocked and proceeding to lock the mutex at the same time? If so, what's a good way to work around this problem? class Mutex { bool Locked; public: Mutex() { Locked = false; } void lock() { while (Locked); Locked = true; } void unlock() { Locked = false; } }; // Thread 1: mutex.lock() SharedData->operationAlpha(); mutex.unlock(); // Thread 2: mutex.lock() SharedData->operationBeta(); mutex.unlock();

General and Gameplay Programming Programming

Started by OpOpOpOp January 19, 2014 07:36 AM

20 comments, last by OpOpOpOp 10 years, 2 months ago

ultramailman

1,720

January 21, 2014 05:53 AM

can't type anything ;-;

press ctrl-c to send interrupt signal, that will interrupt your program and let you look around. Then you will get a prompt "(gdb)", and you can type in "thread <thread number>" to look at different threads. When you are ready to continue the program, type in "c".

OpOpOpOp

154

Author

January 28, 2014 12:43 AM

I finally solved this problem. Well, more like worked around it. I made both threads communicate through a socket instead of a shared array. At first I thought this would waste memory but then I realized that thread A doesn't really need to access the array, it simply adds data to the end of it.

Thanks everybody who helped! :D

Are mutexes really fool-proof?

This topic is closed to new replies.

Popular Topics

Recommended Tutorials

Are mutexes really fool-proof?

This topic is closed to new replies.

Popular Topics

Recommended Tutorials

Reticulating splines