【如何用信号量实现进程间通信，线程间同步】

 System V信号量和Posix信号量区别

Linux信号量（1）-SYSTEM V - 知乎 (zhihu.com)

System V 实现进程间通信：

(16条消息) 进程间通信方式——信号量（Semaphore）_sky_Mata的博客-优快云博客

POSIX有名信号量实现线程间同步

#include <iostream>
#include <thread>
#include<semaphore.h>
#include <unistd.h>
using namespace std;

sem_t sem;
void WaitSem()
{
  while(1)
  {
    std::cout << this_thread::get_id() << " I am wait_sem" << std::endl;
    sem_wait(&sem);
    std::cout << this_thread::get_id() << " I get get_sem" << std::endl;
  }
}

void PostSem()
{
  while(1)
  {
    while(1)
    {
      sleep(1);
      std::cout << this_thread::get_id() << " I am runing sem_post begin" << std::endl;
      sem_post(&sem);
      std::cout << this_thread::get_id() << " I am runing sem_post end" << std::endl;
    }
  }
}

int main()
{
  // 线程间共享
  sem_init(&sem, 0, 0);
  thread t1(WaitSem);
  thread t2(PostSem);
  t1.join();
  t2.join();
  return 0;
}