在 C++ 中处理大量的执行时间分析 [英] Dealing with heavy profiling of execution times in C++

问题描述

我目前正在从事一个涉及大量数据和复杂算法的科学计算项目，因此我需要进行大量代码分析.我目前依靠 和 clock_t 来计时我的代码的执行.我对这个解决方案非常满意......除了我基本上对所有内容进行计时，因此对于每一行真实代码我必须调用 start_time_function123 = clock(), end_time_function123 = clock() 和 cout <<"function123 执行时间:" <<(end_time_function123-start_time_function123)/CLOCKS_PER_SEC <<结束.这会导致严重的代码膨胀并很快使我的代码变得不可读.你会怎么处理?

I'm currently working on a scientific computing project involving huge data and complex algorithms, so I need to do a lot of code profiling. I'm currently relying on <ctime> and clock_t to time the execution of my code. I'm perfectly happy with this solution... except that I'm basically timing everything and thus for every line of real code I have to call start_time_function123 = clock(), end_time_function123 = clock() and cout << "function123 execution time: " << (end_time_function123-start_time_function123) / CLOCKS_PER_SEC << endl. This leads to heavy code bloating and quickly makes my code unreadable. How would you deal with that?

我能想到的唯一解决方案是找到一个 IDE，允许我标记代码的一部分(在不同的位置，甚至在不同的文件中)，并通过一个按钮切换隐藏/显示所有标记的代码.这将允许我在大部分时间隐藏与分析相关的代码部分，并仅在我想要的时候显示它.

The only solution I can think of would be to find an IDE allowing me to mark portions of my code (at different locations, even in different files) and to toggle hide/show all marked code with one button. This would allow me to hide the part of my code related to profiling most of the time and display it only whenever I want to.

推荐答案

有一个 RAII 类型，将代码标记为定时.

Have a RAII type that marks code as timed.

struct timed {
  char const* name;
  clock_t start;
  timed( char const* name_to_record):
    name(name_to_record),
    start(clock())
  {}
  ~timed(){
    auto end=clock();
    std::cout << name << " execution time: " << (end-start) / CLOCKS_PER_SEC << std::endl;
  }
};

使用它:

void foo(){
  timed timer(__func__);
  // code
}

噪音小得多.

您可以使用基于非作用域的完成操作进行扩充.在进行大量分析时，有时我喜欢包含唯一的 id.将 cout 与 endl 一起使用可能会导致它支配时间；以异步方式转储到大缓冲区的快速记录可能是最佳的.如果你需要计时毫秒级的时间，甚至应该避免分配、锁和字符串操作.

You can augment with non-scope based finish operations. When doing heavy profiling sometimes I like to include unique ids. Using cout esoecially with endl could result in it dominating timing; fast recording to a large buffer that is dumped out in an async manner may be optimal. If you need to time ms level time, even allocation, locks and string manipulation should be avoided.

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