# Benchmark

emqtt_bench (opens new window) is a concise and powerful MQTT protocol performance testing tool written with Erlang. If you need testing services with large-scale scenarios and in-depth customization , the test service provided by EMQ partners XMeter (opens new window) is recommended.

# Compile and install

The operation of emqtt_bench depends on the operating environment of Erlang/OTP 21.2 and above version. The installation process is skipped. For details, please refer to the online installation tutorials.

After the Erlang environment is installed, download the latest code of emqtt-bench and compile it:

git clone https://github.com/emqx/emqtt-bench
cd emqtt-bench


After the compilation, an executable script named emqtt_bench will be generated in the current directory. Execute the following command to confirm that it can be used normally:

Usage: emqtt_bench pub | sub | conn [--help]

The output of the above content proves that emqtt_bench has been correctly installed on the host.

# Use

There are three subcommands of emqtt_bench:

  1. pub: used to create a large number of clients to perform the operation of publishing messages.
  2. sub: Used to create a large number of clients to subscribe to topics and receive messages.
  3. conn: used to create a large number of connections.

# Publish

When executing ./emqtt_bench pub --help, you will get the available parameter output.

ParameterabbreviationOptional valueDefault valueDescription
--host-h-localhostAddress of the MQTT server to connect
--port-p-1883MQTT service port
5MQTT protocol version used
--count-c-200Total number of clients
--startnumber-n-0Start number of clients
--interval-i-10Interval to create a client; unit: ms
--interval_of_msg-I-1000Interval to publish a message
--username-u-None; optionalClient username
--password-P-None; optionalClient password
--topic-t-None; requiredPublished topics; support placeholders:
%c: ClientId
%u: Username
%i:Client's sequence number
--szie-s-256Message Payload size; unit: bytes
--qos-q-0Qos level
falseWhether the message sets the Retain flag
--keepalive-k-300Client keepalive time
trueWhether to establish a connection by cleaning the session
falseWhether to enable SSL
--certfile--NoneClient SSL certificate
--keyfile--NoneClient SSL key file
falseWhether to establish a connection via Websocket
--ifaddr--NoneSpecifies the local network card used by the client connection

For example, we start 10 connections and send 100 Qos0 messages to the topic t every second, where the size of each message payload is16 bytes:

./emqtt_bench pub -t t -h emqx-server -s 16 -q 0 -c 10 -I 10

# Subscribe

Execute ./emqtt_bench sub --help to get all available parameters of this subcommand. Their explanations have been included in the table above and are omitted here.

For example, we start 500 connections, and each subscribes to the t topic with Qos0:

./emqtt_bench sub -t t -h emqx-server -c 500

# Connect

Execute ./emqtt_bench conn --help to get all available parameters of this subcommand. Their explanations have been included in the table above and are omitted here.

For example, we start 1000 connections:

./emqtt_bench conn -h emqx-server -c 1000

# SSL connection

emqtt_bench supports establishing a secure SSL connection and performing tests.

One-way certificate:

./emqtt_bench sub -c 100 -i 10 -t bench/%i -p 8883 -S
./emqtt_bench pub -c 100 -I 10 -t bench/%i -p 8883 -s 256 -S

Two-way certificate:

./emqtt_bench sub -c 100 -i 10 -t bench/%i -p 8883 --certfile path/to/client-cert.pem --keyfile path/to/client-key.pem
./emqtt_bench pub -c 100 -i 10 -t bench/%i -s 256 -p 8883 --certfile path/to/client-cert.pem --keyfile path/to/client-key.pem

# Typical stress test scenario

# Scenario description

We verify the use of the tool in 2 most typical scenarios:

  1. Connections: Use emqtt_bench to create millions of connections to EMQ X Broker.
  2. Throughput: Use emqtt_bench to create 10W / s Qos0 message throughput in EMQ X Broker.

# Device and deployment topology

A total of three 8C16G servers need to be prepared, one for EMQX Broker and two for client presses:

  • System: CentOS Linux release 7.7.1908 (Core)

  • CPU: Intel Xeon Processor (Skylake) Main frequency: 2693.670 MHZ

  • Server: emqx-centos7-v4.0.2.zip

  • Press:emqtt-bench v0.3.1

    • Each press is configured with 10 network cards, which are used to establish a large number of MQTT client connections in the connection test

The topology structure is as follows:

	| bench1: | -------					+--------------------------+
	+-----------------------+        \----->  |		    EMQ X Broker			 |
	+-----------------------+        /----->  |	  	 |
	| bench2: | -------					+--------------------------+

# Tuning

Both the client's press and the server's machine need to perform system parameter tuning, refer to Tuning guide.

# Connection test

After performing system tuning, start the server:

./bin/emqx start

Then start 50 thousand connections on each network card on bench1, which is a total of 50w connections:

./emqtt_bench -h -c 50000 --ifaddr
./emqtt_bench -h -c 50000 --ifaddr
./emqtt_bench -h -c 50000 --ifaddr
./emqtt_bench -h -c 50000 --ifaddr
./emqtt_bench -h -c 50000 --ifaddr
./emqtt_bench -h -c 50000 --ifaddr
./emqtt_bench -h -c 50000 --ifaddr
./emqtt_bench -h -c 50000 --ifaddr
./emqtt_bench -h -c 50000 --ifaddr
./emqtt_bench -h -c 50000 --ifaddr

Perform the same operation on bench2.

After all connections are established, execute ./bin/emqx_ctl listeners and find the following content to view the information about the number of connections in EMQ X Broker:

listener on mqtt:tcp:
  acceptors       : 8
  max_conns       : 1024000
  current_conn    : 1000000
  shutdown_count  : []

# Throughput test

Similarly, first start the server:

./bin/emqx start

Start 500 subscription clients in bench1:

./emqtt_bench sub -t t -h -c 500

Then start 20 publishers on bench2 and publish 10 messages per second:

./emqtt_bench pub -t t -h -c 20 -I 100

Then, go back to the subscribing client on bench1, you can see the current rate of receiving messages:

recv(28006): total=2102563, rate=99725(msg/sec)