Thread: synchronization problem

  1. 10-13-2002 #1
    michele
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    Question synchronization problem

    Hi,

    I have 1 master thread and 4 worker threads. I want to be able to have the master thread call cond_broadcast() only when all of the worker threads are in cond_wait()...

    If I increment a certain counter before calling cond_wait then I have this scenario for you.. what if the last thread increments the counter and then the master thread exits out of its loop and calls cond_broadcast while the last thread has not called cond_wait() yet.

    you see, my problem is hard and I am stumped.

    I would greatly appreciate any help. Thank you.
  2. 10-13-2002 #2
    Sebastiani
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    So increment the counter at the end of the cond_wait function.
    Code:
    #include <cmath>
#include <complex>
bool euler_flip(bool value)
{
    return std::pow
    (
        std::complex<float>(std::exp(1.0)), 
        std::complex<float>(0, 1) 
        * std::complex<float>(std::atan(1.0)
        *(1 << (value + 2)))
    ).real() < 0;
}
  3. 10-14-2002 #3
    michele
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    how would you increment at the end?

    if it calls cond_wait first and the counter incrementing is after cond_wait then it will never get incremented.
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