[英]Multithreading with vectors in C++
Based on this code , I am trying to do a simple multithread program where the number of threads is determined in the input arguments as num_threads
and these threads must call the same method with a given input parameters. 基于此代码 ,我试图做一个简单的多线程程序,其中在输入参数中将线程数确定为num_threads
并且这些线程必须使用给定的输入参数调用相同的方法。
The problem arises when num_items > num_threads
due to the redefinition of thread_id
(despite the fact that all the threads are joined after their use).Does anyone know where am I failing? 当由于重新定义thread_id
而导致num_items > num_threads
时出现问题(尽管所有线程在使用后都已连接),有人知道我在哪里失败吗?
vector<thread> thread_id;
int it = num_items/num_threads + (num_items%num_threads != 0);
for(int i = 0; i < it; i++){
for(int j = 0; j < num_threads; ++j)
thread_id.push_back(thread(method1, "parameter", i*num_threads + j));
for(auto& t : threadId)
t.join();
}
The error code is the following: 错误代码如下:
terminate called after throwing an instance of 'std::system_error'
what(): Invalid argument
Since you're only always adding to the vector, the old thread handles stay there and you try to re- join
them (along with the new ones) which is a std::system_error
as documented . 因为你永远只增加了向量,旧的线程句柄呆在那里,并尝试重新join
他们(用新的沿),这是一个std::system_error
作为记录 。
Try this at the end of your j
-loop: 在您的j
-loop末尾尝试以下操作:
thread_id.clear()
Also, note that a multiple of num_threads
will always be created, which will be equal to or greater than num_items
. 另外,请注意,将始终创建多个num_threads
,等于或大于num_items
。 You may want to treat the last iteration differently (just add a condition on the value of i*num_threads + j
). 您可能希望以不同的方式对待最后一次迭代(只需在i*num_threads + j
的值上添加一个条件)。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.