I want to store ~3,000,000 double values at unsigned int indices under VS2010 C++. I use a std::tr1:unordered_map<unsigned int, double> for this purpose. Unfortunately, when I try to store value number 2^21, an exception is thrown (as if there is only space for 2^21-1 , i.e., some index can only use 20 Bits). I tried to rehash before storing the values, which did not work either.
Finally I ended up with some very basic test program (which showed even a little different behavior, but anyway):
std::tr1::unordered_map<unsigned int, float> mapOut;
//mapOut.rehash(SOMESIZE);
for (unsigned int i=0; i<3000000; i++)
{
if (i%1000==0) std::cout << i << std::endl;
mapOut[i] = 0.0;
}
Some cases I checked:
1) If I do not rehash at all, the program takes a long break after the output according to i == 32000 (eventually 2^15) and then continues to i == 262000 (2^18). There it holds forever (with 100% CPU load, memory not increasing).
2) If I do a rehash(1000), it comes to i == 65000 (2^16) and holds forever (CPU load 100%, memory not increasing).
3) If I do a rehash(3000000), the loop is successfully finished, but the program never exits - i.e., obviously there is some problem with the destructor.
What is going on there, and even more important: What should I do about it?!
Many thanks for your help!