Configure a couple of hidden options for VerneMQ
There are a couple of hidden options you can set in the
vernemq.conf file. Hidden means that you have to add and set the value explicitly. Hidden options still have default values. Changing them should be considered advanced, possibly with the exception of setting a
Queue Deliver mode
Specify how the queue should deliver messages when multiple sessions are allowed. In case of
fanout all the attached sessions will receive the message, in case of
balance an attached session is choosen randomly.
queue_deliver_mode = balance
Specify how queues should process messages, either the
lifo way. Default is
queue_type = fifo
Max Message Rate
Specifies the maximum incoming publish rate per session per second. Depending on the underlying network buffers this rate isn't enforced. Defaults to
0, which means no rate limits apply. Setting to a value of
2 limits any publisher to 2 messages per second, for instance.
max_message_rate = 2
Max Drain Time
Due to the eventual consistent nature of the subscriber store it is possible that during queue migration messages still arrive on the old cluster node. This parameter enables to compensate this by keeping the queue around for some time (in seconds) after it was migrated to the other cluster node.
max_drain_time = 20
Max Msgs per Drain Step
Specifies the number of messages that are delivered to the remote node per drain step. A large value will provide a faster migration of a queue, but increases the waste of bandwidth in case the migration fails.
max_msgs_per_drain_step = 1000
Default Reg View
Allows to select a new default reg_view. A reg_view is a pre-defined way to route messages. Multiple views can be loaded and used, but one has to be selected as a default. The default routing is
vmq_reg_trie, i.e. routing via the built-in trie data structure.
vmq_reg_view = "vmq_reg_trie"
A list of views that are started during startup. It's only used in plugins that want to choose dynamically between routing reg_views.
reg_views = "[vmq_reg_trie]"
Outgoing Clustering Buffer Size
An integer specifying how many bytes are buffered in case the remote node is not available. Default is
outgoing_clustering_buffer_size = 15000