never mind... i did not fully understand condition variable implementation when open this issue...
previously, i did not realize that the outer mutex lock guarantees the atomic operation for condition
and within the implementation of inner waiting queue, inner mutex lock guarantees the atomic operation for the inner waiting queue
never mind... i did not fully understand condition variable implementation when open this issue...
previously, i did not realize that the outer mutex lock guarantees the atomic operation for condition and within the implementation of inner waiting queue, inner mutex lock guarantees the atomic operation for the inner waiting queue