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1.12.3
Welcome
Getting Started
Downloads
VerneMQ / MQTT Introduction
Installing VerneMQ
Installing on Debian and Ubuntu
Installing on CentOS and RHEL
Running VerneMQ using Docker
Configuring VerneMQ
Introduction
The VerneMQ conf file
Auth using files
Auth using a database
MQTT Options
MQTT Listeners
HTTP Listeners
Non-standard MQTT options
Websockets
Logging
Consumer session balancing
Plugins
Shared subscriptions
Advanced Options
Storage
MQTT Bridge
VerneMQ Clustering
Introduction
Inter-node Communication
Dealing with Netsplits
Live Administration
Introduction
Inspecting and managing sessions
Retained messages
Live reconfiguration
Managing Listeners
HTTP API
Tracing
Monitoring
Introduction
$SYSTree
Graphite
Netdata
Prometheus
Health Checker
Status Page
Plugin Development
Introduction
Session lifecycle
Subscribe Flow
Publish Flow
Enhanced Auth Flow
Erlang Boilerplate
Lua Scripting Support
Webhooks
Misc
Loadtesting VerneMQ
Not a tuning guide
Change Open File Limits
Guides
A typical VerneMQ deployment
VerneMQ on Kubernetes
Loadtesting VerneMQ
Clustering during development
Not a tuning guide
Change Open File Limits
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MQTT Options

Retry Interval

Set the time in seconds after a QoS=1 or QoS=2 message has been sent that VerneMQ will wait before retrying when no response is received.
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retry_interval = 20
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This option default to 20 seconds.

Inflight Messages

This option defines the maximum number of QoS 1 or 2 messages that can be in the process of being transmitted simultaneously.
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max_inflight_messages = 20
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Defaults to 20 messages, use 0 for no limit. The inflight window serves as a protection for sessions, on the incoming side.

Load Shedding

The maximum number of messages to hold in the queue above those messages that are currently in flight. Defaults to 1000. Set to -1 for no limit. This option protects a client session from overload by dropping messages (of any QoS).
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max_online_messages = 1000
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Defaults to 1000 messages, use -1 for no limit. This parameter was named max_queued_messages in 0.10.*. Note that 0 will totally block message delivery from any queue!
This option specifies the maximum number of QoS 1 and 2 messages to hold in the offline queue.
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max_offline_messages = 1000
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Defaults to 1000 messages, use -1 for no limit, use 0 if no messages should be stored.
In contrast to the session based inflight window, max_online_messages and max_offline_messages serves as a protection of queues, on the outgoing side.
Configuring VerneMQ - Previous
Auth using a database
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MQTT Listeners
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Contents
Retry Interval
Inflight Messages
Load Shedding