title: Any multi-thread concern on memcpy function?
body: <pre><code>memcpy(a, b, sizeof(a));
  </code></pre>
  
  <p>v.s.</p>
  
  <pre><code>a[0] = b[0];
  a[1] = b[1];
  ...
  </code></pre>
  
  <p>Suppose that <code>memcpy</code> should have smaller code size and high efficiency, but is there any risk to <code>memcpy</code> in multi-thread system?</p>