具有多个线程和互斥锁的竞争状况

Question

int iGlobe = 0;
...
void thread1Func()
{
  Lock(&Mutex1);
  if(iGlobe == 0)         //step-1
    someaction();
}
...
void thread2Func()
{
  Lock(&Mutex2);
  iGlobe = 5;             //step-2
}

Suppose,

1) Thread1 executes step-1 and goes to sleep

2) Meanwhile Thread2 executes step-2 and changes value of iGlobe

How to overcome this situation?

Answer 1

All accesses to a given piece of data have to synchronize on the same mutex, otherwise there is no "mutual exclusion" effect. So, to fix your code, change thread2Func to say Lock(&Mutex1) .