The semantics are the same as for any threaded use of a callback queue.  What that means exactly depends on the callback you&#39;re talking about, so, for example, subscription callbacks on a single topic will not happen in multiple threads at once unless it&#39;s enabled in SubscribeOptions.<div>

<br></div><div>Josh<br><div><br><div class="gmail_quote">On Fri, Nov 26, 2010 at 9:46 AM, Jack O&#39;Quin <span dir="ltr">&lt;<a href="mailto:jack.oquin@gmail.com">jack.oquin@gmail.com</a>&gt;</span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">

Despite searching the nodelet code and documentation, I&#39;m having<br>
trouble grasping the semantics of multi-threaded nodelets.<br>
<br>
When would I want to call the getMT* methods for callback queues and<br>
node handles? What advantages do they provide?<br>
<br>
What are their threading and locking requirements, versus the<br>
single-thread versions?<br>
<br>
Is there any plan for a Documentation review of the nodelets package?<br>
<font color="#888888">--<br>
 joq<br>
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