Shulou(Shulou.com)06/01 Report--

This article mainly explains how C++ passes a small amount of data between threads. Interested friends may wish to take a look. The method introduced in this paper is simple, fast and practical. Let Xiaobian take you to learn "C++ how to pass a small amount of data between threads"!

CP.31: Passing small amounts of data between threads by value instead of references or pointers

Reason

The replication and access costs of small amounts of data provided in copy form are lower than sharing using some locking mechanism. Copy operations naturally guarantee uniqueness of ownership (simplified code) and avoid possible data races.

Note:

Defining "small amount" precisely is impossible.

It is impossible to define precisely what is meant by "small amounts."

Example

string modify1(string);

void modify2(string&);

void fct(string& s)

{

auto res = async(modify1, s);

async(modify2, s);

}

The procedure calling modify1 contains two copies of the value of string; the procedure calling modify2 does not. On the other hand, the implementation of modify1 is identical to single-threaded code, whereas modify2 requires some form of mutex to avoid data contention. If it's a short string (say 10 characters), the call to modify1 is surprisingly fast, basically the cost of the thread switch. If it is a long string (e.g. 1,000,000 characters), copying it twice may not be a good idea.

Note that parameter handling does nothing for asynchronous operations. The same judgment applies when considering message versus shared memory.

At this point, I believe everyone has a deeper understanding of "how C++ passes a small amount of data between threads," so let's actually operate it! Here is the website, more related content can enter the relevant channels for inquiry, pay attention to us, continue to learn!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.