C++ Thread: terminate called without an active exception - c++

Question

I'm trying to create one array of integers without repeat. To get arrays of length more than 1000, it takes a lot of time to make. So, I thought using thread would be a good decision. But I'm writing something wrong. So far following are my code:
utils.h
#ifndef UTILS_H
#define UTILS_H
typedef long long int64; typedef unsigned long long uint64;
class utils
{
public:
utils();
virtual ~utils();
static int getRandomNumberInRange(int min, int max);
static int* getRandomArray(int size, bool isRepeatAllowed);
protected:
private:
};
#endif // UTILS_H
utils.cpp
#include <iostream>
#include <cstdlib>
#include <ctime>
#include <cmath>
#include <vector>
#include <algorithm> // for std::find
#include <sys/time.h>
#include <cctype>
#include <string>
#include <thread>
#include <vector>
#include "utils.h"
utils::utils()
{
}
utils::~utils()
{
}
int utils::getRandomNumberInRange(int min, int max)
{
if (min > max) {
int aux = min;
min = max;
max = aux;
}
else if (min == max) {
return min;
}
return (rand() % (max - min)) + min;
}
void getUniqueInteger(int* arr, int last, int* newVal)
{
int val = *newVal;
while(std::find(arr, arr+last, val) != arr+last)
{
val = utils::getRandomNumberInRange(10, 10000);
}
arr[last] = val;
}
int* utils::getRandomArray(int size, bool isRepeatAllowed)
{
int* arr = new int[size], newVal = 0;
std::vector<std::thread *> threadArr;
for (int i = 0; i < size; i++)
{
newVal = utils::getRandomNumberInRange(10, 1000);
if(!isRepeatAllowed)
{
std::thread newThread(getUniqueInteger, arr, i, &newVal);
threadArr.push_back( &newThread);
}
else
{
arr[i] = newVal;
}
}
int spawnedThreadCount = threadArr.size();
if (spawnedThreadCount > 0)
{
for (int j = 0; j < spawnedThreadCount; j++)
{
threadArr[j]->join();
//delete threadArr[j];
}
}
return arr;
}
And calling this in:
main.cpp
#include <iostream>
#include <cstdlib>
#include <ctime>
#include <string>
#include "utils.h"
using namespace std;
int main(int argc, char *argv[])
{
if (argc != 2 && utils::isInteger(argv[1]))
{
cout << "You have to provide an integer input to this program!!!" << endl;
return 0;
}
int size = stoi( argv[1] );
srand(time(NULL));
int* arr = utils::getRandomArray(size, false);
return 0;
}
Compiling by: g++ -Wall -g -std=c++11 -pthread -o a.out ./utils.cpp ./main.cpp
But, whenever I'm running the program by ./a.out 10, it's terminating by giving the output:
terminate called without an active exception
Aborted (core dumped)
Please help. Thanks in advance.

Answer 1

Your code that creates the thread creates a stack variable that is immediately destroyed. You need to change this:
if(!isRepeatAllowed)
{
std::thread newThread(getUniqueInteger, arr, i, &newVal);
threadArr.push_back( &newThread);
}
to this:
if(!isRepeatAllowed)
{
std::thread* newThread = new std::thread(getUniqueInteger, arr, i, &newVal);
threadArr.push_back( newThread);
}
Then uncomment your delete line later on.

Answer 2

You create your thread inside the if statement. Then you push a pointer to it by getting a reference. This pointer will not keep the thread object alive, rather when the if is exited your object's destructor is called.
This means that std::terminate is called to terminate the running thread and you're left with a dangling pointer.