I tried to implement a SPSC with lock free tech And got a quirky Segmentation fault. the code following:
#include <iostream>#include <thread>#include <vector>#include <atomic>#define MATTER_NUM 10000#define BUF_LEN 1024uint64_t RingBuffer[BUF_LEN];//uint32_t m_buffer[BUF_LEN];std::atomic<uint64_t> head(0);std::atomic<uint64_t> tail(0);bool Push(const uint64_t &data) { uint64_t tmp_tail = tail.load(std::memory_order_relaxed); if ((tmp_tail + 1) % BUF_LEN == head.load(std::memory_order_acquire)) return false; RingBuffer[tmp_tail + 1] = data; tail.store((tmp_tail + 1) % BUF_LEN, std::memory_order_release); return true;}bool Pop(uint64_t &data) { static uint64_t cnt = 0; uint64_t tmp_head = head.load(std::memory_order_relaxed); if (tmp_head == tail.load(std::memory_order_acquire)) return false; data = RingBuffer[tmp_head]; head.store((tmp_head + 1) % BUF_LEN, std::memory_order_release); cnt = (tmp_head + 1) % BUF_LEN; return true;}int Producer() { for (int i = 0; i < MATTER_NUM; i++) { while (!Push(i)); } return 0;}int Consume() { for (int i = 0; i < MATTER_NUM; i++) { uint64_t data = -1; while (!Pop(data)); std::cout << data << std::endl; } return 0;}int main(){ std::thread t1(Producer), t2(Consume); t1.join(); t2.join(); return 0;}There are a quirky phenomenon. When I cancel the comment "uint32_t m_buffer[BUF_LEN]" in line 10, the code magically normal run! I can't understand why this is happening.
Build in g++ (GCC) 7.5.0:g++ -std=c++11 -pthread main.cpp && ./a.out