what(): std::bad_alloc - am I out of memory?

问题

My dataset: 500,000 points in 960 dimensions. The size of the file is 1.9 GB (1,922,000,000 bytes).

The code works for smaller data sets, but for this it will crash in the same point every time. Here is a minimal example:

#include <iostream>
#include <vector>

template<typename T>
class Division_Euclidean_space {
 public:
  /**
   * The data type.
   */
  typedef T FT;

  /**
   * Constructor, which
   * sets 'N' and 'D' to zero.
   */
  Division_Euclidean_space()
      : N(0),
        D(0) {

  }

  /**
   * @param n - size of data
   */
  void setSize(size_t& n) {
    N = n;
  }

  /**
   * @param n - size of data
   */
  void setSize(int n) {
    N = n;
  }

  /**
   * Get the number of points
   *
   * @return - the number of points
   */
  const size_t& size() const {
    return N;
  }

  /**
   * Get the dimension of points
   *
   * @return - the dimension
   */
  const int dim() {
    return D;
  }

  /**
   * @param d - dimension of data
   */
  void setDim(int& d) {
    D = d;
  }

  /**
   * \brief Inserts a new value to the collection of
   * points, held in the private vector.
   *
   * @param v - value to be inserted
   */
  void insert(FT v) {
    p.push_back(v);
  }

 private:
  /**
   * number of points
   */
  size_t N;
  /**
   * dimension of points
   */
  int D;
  /**
   * vector of points
   * Note that indexing is of the form: [i * D + j]
   */
  std::vector<FT> p;
};

typedef Division_Euclidean_space<int> Division_space;
typedef Division_space::FT FT;

template<typename T>
void readDivisionSpacefvecs(Division_Euclidean_space<T>& ds, int& N, int& D,
                            char* filename) {
  FILE* fid;
  fid = fopen(filename, "rb");
  if (!fid)
    printf("I/O error : Unable to open the file %s\n", filename);

  // we assign the return value of fread() to 'sz' just to suppress a warning
  size_t sz = fread(&D, sizeof(D), 1, fid);
  fseek(fid, 0L, SEEK_END);
  sz = ftell(fid);
  N = sz / (1 * 4 + D * 4);
  //printf("N = %d, D = %d, |%s|\n", N, D, filename);

  fseek(fid, 0L, SEEK_SET);
  ds.setSize(N);
  ds.setDim(D);
  std::cout << ds.dim() << " " << ds.size() << "\n";
  int c = 0;
  float v;
  int i, j;
  for (i = 0; i < N; ++i) {
    sz = fread(&D, sizeof(D), 1, fid);
    //printf("%d\n", D);
    for (j = 0; j < D; ++j) {
      sz = fread(&v, sizeof(v), 1, fid);
      if (c >= 279619)
        printf("j = %d, v = %f, read up to point %d\n", j, v, c);
      ds.insert(v);
    }
    ++c;
    printf("read up to %d\n", c);
  }
  if (c != N)
    printf("WARNING! Read less points than expected.\n");
}

int main() {
  Division_space test;
  int N, D;
  readDivisionSpacefvecs<FT>(test, N, D, "../../parallel/rkd_forest/Datasets/gist/gist_learn.fvecs");

  return 0;
}

Output:

...
j = 255, v = 0.052300, read up to point 279620
j = 256, v = 0.052300, read up to point 279620
terminate called after throwing an instance of 'std::bad_alloc'
  what(): std::bad_alloc
Aborted

Am I out of memory? How can I know?

Here is how much memory I have:

samaras@samaras-A15:~$ free -mt
             total       used       free     shared    buffers     cached
Mem:          3934       2638       1295          0        179       1000
-/+ buffers/cache:       1458       2475
Swap:         3987          0       3987
Total:        7922       2638       5283

回答1:

std::bad_alloc means a problem with allocating a memory - so yes, you're most likely out of memory. Unfortunately, there is no a reliable way to "handle" this kind of exception - you can catch it and gratefully exit application.

来源：https://stackoverflow.com/questions/29309681/what-stdbad-alloc-am-i-out-of-memory

标签

c++

memory

bad-alloc