![](/img/trans.png)
[英]Would this std::vector push_back in OpenMP parallel region result in false-sharing?
[英]Is it safe to use vector push_back in an OpenMP parallel region?
我知道我不應該在openmp並行區域內引發任何未捕獲的異常。 因此,我認為以下循環並不安全,因為vector的push_back函數可能導致內存重新分配,從而有可能引發異常。
我查閱了文檔,並說If a reallocation happens, the strong guarantee is also given if the type of the elements is either copyable or no-throw moveable.
那我的代碼安全嗎? Star是包含浮點數的基本數據結構。
std::vector<Star> stars;
#pragma omp parallel for
for(size_t i = 1; i < (gimg.height() - 1) * 2; i++)
{
float i_ = i / 2.0f;
for(float j = 1; j < gimg.width() - 1; j += 0.5f)
{
//a b c
//d e f
//g h k
quantum_t e = gimg.bilinear(j, i_);
quantum_t a = gimg.bilinear(j - 1, i_ - 1);
if(a >= e) continue;
quantum_t b = gimg.bilinear(j, i_ - 1);
if(b >= e) continue;
quantum_t c = gimg.bilinear(j + 1, i_ + 1);
if(c >= e) continue;
quantum_t d = gimg.bilinear(j - 1, i_);
if(d >= e) continue;
quantum_t f = gimg.bilinear(j + 1, i_);
if(f >= e) continue;
quantum_t g = gimg.bilinear(j - 1, i_ + 1);
if(g >= e) continue;
quantum_t h = gimg.bilinear(j, i_ + 1);
if(h >= e) continue;
quantum_t k = gimg.bilinear(j + 1, i_ + 1);
if(k >= e) continue;
bool ismax = d >= a && d >= g && h >= g && h >= k && f >= k && f >= c && b >= c && b >= a;
if(ismax)
{
Star s;
s.brightness = e;
s.location = Point<float>(j, i_);
#pragma omp critical
stars.push_back(s);
}
}
}
OpenMP標准在第2.7.1節結尾處說:
在循環區域內執行的throw必須使執行在循環區域的同一迭代中恢復,並且引發異常的同一線程必須捕獲該異常。
因此,將push_back()
構造本身包含在try
- catch
構造中,使其位於critical
區域內,應該可以確保您的代碼安全。
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.