This is a new features release. Note that although the number of changes is relatively small, there is a fairly major change in the network socket handling (to allow >1024 clients) , which is one reason this has been treated as a separate release.


  • Use poll() instead of select() to allow >1024 clients.
  • Implement max_connections.
  • Run VACUUM on in-memory database on receiving SIGUSR2.
  • mosquitto_pub can now send null (zero length) messages.
  • Add option to print debug messages in pub and sub clients.
  • hg revision is now exported via $SYS/broker/changeset
  • Add compile time option to disable heap memory tracking.

Bug fixes:

  • Don't store QoS=0 messages for disconnected clients with subscriptions of QoS>0.
  • accept() all available sockets when new clients are connecting, rather than just one (performance advantage)
  • Send Will when client exceeds keepalive timer and is disconnected.
  • Check to see if a client has a will before sending it.
  • Correctly deal with clients connecting with the same id multiple times.
  • Fix bridge keepalive timeouts and reconnects.
  • Don't attempt to drop root privileges when running on Windows as this isn't well supported (bug #586231).

Source downloads are available at the download page Links for binary packages on Ubuntu and Fedora can be found on the same page.