Parallel nested outer for loop

[dataPulverizer]

I am trying to parallelize kernel matrix calculations using threadpool:
    
    
    proc calculateKernelMatrix*(K: AbstractKernel, data: Matrix[F]): Matrix[F] =
      let n = int64(ncol(data));
      var mat = Matrix[F](data: newSeq[F](n*n), dim: @[n, n]);
      for j in 0..<n:
        for i in j..<n:
          var tmp: F;
          spawn kernel(K, data.col(i), data.col(j), tmp.addr);
          mat[i, j] = tmp;
          mat[j, i] = tmp;
        sync();
      return mat;
    
    
    Run

I'd like each j to run in a new thread rather than each (i, j).