std::this_thread::yield：　當前執行緒放棄執行，作業系統排程另一執行緒繼續執行。即當前執行緒將未使用完的“CPU時間片”讓給其他執行緒使用，等其他執行緒使用完後再與其他執行緒一起競爭"CPU"。
std::this_thread::sleep_for：　表示當前執行緒休眠一段時間，休眠期間不與其他執行緒競爭CPU，根據執行緒需求，等待若干時間。

this_thread 包裝了一組可以訪問當前執行緒資訊的函式

1、get_id()      獲取當前執行緒的id。

// thread::get_id / this_thread::get_id
#include <iostream>       // std::cout
#include <thread>         // std::thread, std::thread::id, std::this_thread::get_id
#include <chrono>         // std::chrono::seconds
 
std::thread::id main_thread_id = std::this_thread::get_id();
 
void is_main_thread() {
  if ( main_thread_id == std::this_thread::get_id() )
    std::cout << "This is the main thread.\n";
  else
    std::cout << "This is not the main thread.\n";
}
 
int main() 
{
  is_main_thread();
  std::thread th (is_main_thread);
  th.join();
}
 

輸出結果

This is the main thread.
This is not the main thread.

2、yield()
呼叫執行緒放棄執行，回到準備狀態，重新分配cpu資源。所以呼叫該方法後，可能執行其他執行緒，也可能還是執行該執行緒

// this_thread::yield example
#include <iostream>       // std::cout
#include <thread>         // std::thread, std::this_thread::yield
#include <atomic>         // std::atomic
 
std::atomic<bool> ready (false);
 
void count1m(int id) {
  while (!ready) {             // wait until main() sets ready...
    std::this_thread::yield();
  }
  for (volatile int i=0; i<1000000; ++i) {}
  std::cout << id;
}
 
int main ()
{
  std::thread threads[10];
  std::cout << "race of 10 threads that count to 1 million:\n";
  for (int i=0; i<10; ++i) threads[i]=std::thread(count1m,i);
  ready = true;               // go!
  for (auto& th : threads) th.join();
  std::cout << '\n';
 
  return 0;
}
 

輸出結果

race of 10 threads that count to 1 million...
6189370542

3、template <class Clock, class Duration>
       void sleep_until (const chrono::time_point<Clock,Duration>& abs_time);
阻塞呼叫執行緒，一直到指定事件

// this_thread::sleep_for example
#include <iostream>       // std::cout
#include <iomanip>        // std::put_time
#include <thread>         // std::this_thread::sleep_until
#include <chrono>         // std::chrono::system_clock
#include <ctime>          // std::time_t, std::tm, std::localtime, std::mktime
 
int main() 
{
  using std::chrono::system_clock;
  std::time_t tt = system_clock::to_time_t (system_clock::now());
 
  struct std::tm * ptm = std::localtime(&tt);
  std::cout << "Current time: " << std::put_time(ptm,"%X") << '\n';
 
  std::cout << "Waiting for the next minute to begin...\n";
  ++ptm->tm_min; ptm->tm_sec=0;
  std::this_thread::sleep_until (system_clock::from_time_t (mktime(ptm)));
 
  std::cout << std::put_time(ptm,"%X") << " reached!\n";
 
  return 0;
}
 

輸出結果

Current time: 11:52:36
Waiting for the next minute to begin...
11:53:00 reached!

4、template <class Rep, class Period>
       void sleep_for (const chrono::duration<Rep,Period>& rel_time);
阻塞呼叫執行緒，一直到指定時間段後。

// this_thread::sleep_for example
#include <iostream>       // std::cout
#include <thread>         // std::this_thread::sleep_for
#include <chrono>         // std::chrono::seconds
 
int main() 
{
  std::cout << "countdown:\n";
  for (int i=10; i>0; --i) {
    std::cout << i << '\n';
    std::this_thread::sleep_for (std::chrono::seconds(1));
  }
  std::cout << "Lift off!\n";
 
  return 0;
}

輸出結果

countdown:
10
9
8
7
6
5
4
3
2
1
Lift off!

參考連結:

https://en.cppreference.com/w/cpp/thread/sleep_for

https://blog.csdn.net/u012085988/article/details/17225325

https://blog.csdn.net/Sandy_WYM_/article/details/83538635