title: Setting limit on post queue size with Boost Asio?
body: <p>I'm using <code>boost::asio::io_service</code> as a basic thread pool. Some threads get added to io_service, the main thread starts posting handlers, the worker threads start running the handlers, and everything finishes. So far, so good; I get a nice speedup over single-threaded code.</p>
  
  <p>However, the main thread has millions of things to post. And it just keeps on posting them, much faster than the worker threads can handle them. I don't hit RAM limits, but it's still kind of silly to be enqueuing so many things. What I'd like to do is have a fixed-size for the handler queue, and have post() block if the queue is full.</p>
  
  <p>I don't see any options for this in the Boost ASIO docs. Is this possible?</p>