title: chrome://tracing displaying more lanes than process_names in timeline.json
body: <p>So far, I have assumed that the number of lanes displayed by the Chrome <a href="https://www.chromium.org/developers/how-tos/trace-event-profiling-tool" rel="nofollow noreferrer">Trace Event Profiling Tool</a> <code>chrome://tracing</code> always matches the number of <code>process_name</code>s defined in a loaded file like <code>timeline.json</code>. This is for timelines that were recorded in <code>TensorFlow</code> and exported to the file with <code>timeline.generate_chrome_trace_format()</code>.</p>
  <p>I now face a situation where <code>timeline.json</code> contains 3 <code>process_name</code>s like this:</p>
  <pre><code>{
      &quot;name&quot;: &quot;process_name&quot;,
      &quot;args&quot;: { &quot;name&quot;: &quot;Allocators&quot; },
      &quot;ph&quot;: &quot;M&quot;, &quot;pid&quot;: 0
  },
  {
      &quot;name&quot;: &quot;process_name&quot;,
      &quot;args&quot;: { &quot;name&quot;: &quot;/job:localhost/replica:0/task:0/device:CPU:0 Compute&quot; },
      &quot;ph&quot;: &quot;M&quot;, &quot;pid&quot;: 1
  },
  {
      &quot;name&quot;: &quot;process_name&quot;,
      &quot;args&quot;: { &quot;name&quot;: &quot;/job:localhost/replica:0/task:0/device:CPU:0 Tensors&quot; },
      &quot;ph&quot;: &quot;M&quot;, &quot;pid&quot;: 2
  },
  </code></pre>
  <p>whereas the tool displays 4 lanes like that:</p>
  <p><a href="https://i.stack.imgur.com/PcO6z.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/PcO6z.png" alt="enter image description here" /></a></p>
  <p>And in the file the single operation <code>softmax_cross_entropy_with_logits/Reshape_1</code> in lane 3 does not reference <code>&quot;pid&quot;: 3</code> but <code>&quot;pid&quot;: 1</code>.</p>
  <p>Is this mismatch a feature (i.e. am I misunderstanding things) or a bug?</p>