我正在测试 std::forward_list 排序性能,生成 1000000 个随机数并插入到 std::forward_list,排序 5 次
#include <forward_list>
#include <chrono>
#include <random>
#include <iostream>
#include <vector>
int main()
{
std::random_device rd;
std::mt19937 gen(rd());
std::uniform_int_distribution<int> dis(-100000000, 100000000);
std::vector<int> v;
for (int i = 0; i < 1000000; ++i) {
v.push_back(dis(gen));
}
std::forward_list<int> *list;
for (int j = 0; j < 5; ++j) {
auto list = new std::forward_list<int>();
for (auto it = v.begin(); it != v.end(); ++it) {
list->insert_after(list->cbefore_begin(), *it);
}
auto start = std::chrono::steady_clock::now();
list->sort();
auto end = std::chrono::steady_clock::now();
std::chrono::duration<double> diff = end - start;
std::cout << diff.count() << " s\n";
delete list;
}
}
用
g++ test2.cpp -o test2
编译这段代码并运行,得到输出
1.56004 s
3.58784 s
3.64035 s
3.58166 s
3.55821 s
如果使用 tcmalloc,用
g++ test2.cpp /usr/local/lib/libtcmalloc_minimal.a -o test2
编译这段代码并运行,得到输出
1.17486 s
1.27712 s
1.22682 s
1.24105 s
1.17127 s
如果删除代码
delete list;
,用g++ test2.cpp -o test2
编译并运行,得到输出
1.38157 s
1.38446 s
1.38761 s
1.36721 s
1.39012 s
所以我认为 tcmalloc 可能会导致一些性能问题?