Running a group of chains
<p>I'm attempting to run a group of chains in Celery.  I create a set of chains:</p>

<pre><code>chains = [celery.chain(a.s(i), b.s(), c.s()) for i in items]
</code></pre>

<p>return wrap this in a group:</p>

<pre><code>group = celery.group(*chains)
</code></pre>

<p>The expectation here is that Celery will then schedule each full chain to run as an independent task.  And indeed, logically, that's what appears to happen.  But there are two problems:</p>

<ol>
<li><p>If the number of chains is large, nothing seems to run. No errors in the Celery or rabbitmq consoles.  (Yes, using rabbitmq.)</p></li>
<li><p>Celery appears to execute the first task of each chain across all tasks in the group before moving to the second task of each chain.  (That is, it appears to unwrap the chains into a group of task <code>a</code>s, task <code>b</code>s, and then task <code>c</code>s.  They are still linked to their corresponding chain entries, but this introduces a delay when certain task <code>a</code>s complete much more quickly than others.</p></li>
</ol>

<p>Any ideas what's going on?</p>