title: Concatenate two big numpy 2D arrays
body: <p>I have two big numpy 2D arrays. One shape is X1 (1877055, 1299), another is X2 (1877055, 1445). I then use </p>
  
  <pre><code>X = np.hstack((X1, X2))
  </code></pre>
  
  <p>to concatenate the two arrays into a bigger array. However, the program doesn't run and exit with code -9. It didn't show any error message. </p>
  
  <p>What is the problem? How can I concatenate such two big numpy 2D arrays?</p>