c++似乎变量不具有多线程的 "flush "

Question

is_master_def:

volatile bool is_master_;

is_master_ 值被另一个线程设置为 true，但似乎 is_master_ 值 dosnt 刷新(它没有计算出发生 fatal error ...) .如果我添加 cout << "foo"<

void MasterSlaveSynchronize::validateSingleMaster(){
    if(is_master_){
        cout << "FATAL ERROR HAS OCCURRED BOTH MASTER";
        if(!is_leader_master_){
            cout << "CHOSE AS VICTIM IN MASTER-MATSER. SET THIS HOST AS SLAVE";
            is_master_ = false;
        }
    }
}

调用者代码:

while(1){
        int n = recvfrom(sockId, buf, HEARBEAT_SIZE, 0, (struct sockaddr *) &from,
                &length);
        if (n < 0) {
            REGISTER_ERROR("Failed to recieved hearbeat");
        } else {
            gettimeofday(&instance_->last_hearbeat_got_, NULL);
            instance_->validateSingleMaster();
        }
}

Answer 1

您希望我发表评论作为回答:

Maybe it does, but because you don't use a newline your output stream doesn't flush.

这种行为在这里得到了很好的解释:

Why does printf not flush after the call unless a newline is in the format string?