生产者，消费者 多线程

#include <iostream>
#include <vector>
#include <thread>
#include <mutex>

const size_t SIZE = 10;
using ElemTy = char;
ElemTy arr[SIZE];

size_t begin = 0;
size_t end = 0;

std::mutex prdc_m;
std::mutex cnsm_m;

void produce() {
  for (;;) {
    if ((end + 1) % SIZE != begin) {
      {
        std::lock_guard<std::mutex> lg(prdc_m);
        arr[end] = ‘o‘;
        end = (end + 1) % SIZE;
        std::cout << "produce and size is " << (end - begin) % SIZE << std::endl;
      }
    }
  }
}

void consume() {
  for (;;) {
    if (begin != end) {
      ElemTy e;
      {
        std::lock_guard<std::mutex> lg(cnsm_m);
        e = arr[begin];
        begin = (begin + 1) % SIZE;
        std::cout << "consume and size is " << (end - begin) % SIZE << std::endl;
      }
    }
  }
}

int main() {
  std::vector<std::thread> vc;
  std::vector<std::thread> vp;
  for (int i = 0; i < 10; ++i) {
    vc.push_back(std::thread(consume));
  }
  for (int i = 0; i < 10; ++i) {
    vp.push_back(std::thread(produce));
  }

  for (auto &t : vc) {
    t.join();
  }

  for (auto &t : vp) {
    t.join();
  }

  return 0;
}