JMeter

We are using JMeter for generating requests. JMeter can generate a report with information how much time requests needed, which requests failed, etc. See also the page Microservices Usage for how JMeter is used for load generation to trigger SLO violations.

In the context of measuring energy consumption JMeter is used as the workload generator by using of a predefined test plan consisting of multiple HTTP requests.

Test Plan

The following sequence diagram visualizes the important steps that are part of the test plan:

The test plan is called t2-project-flexible.jmx that can be used for many different usage case scenarios by configure it via JVM parameters (used internally as environment variables).

The basic command for executing the test plan with JMeter without optional parameters looks like this:

jmeter -Jhostname=backend -Jport=8080 -n -t t2-project-flexible.jmx

This command ensures the execution of three requests as shown in the sequence diagram to the target URL http://backend:8080. The loop is run once, as only one product is added to the shopping cart by default in the test plan.

Numerous optional parameters are defined in the test plan, which can be used, for example, to run the loop several times or to execute the requests from several users in parallel. Optional logging is also integrated into the test plan (not shown in the diagram), which can be activated with an environment variable. Logging can be useful for debugging purposes or for calculating the SCI score. A request with all the available parameters looks like this:

jmeter -Jhostname=backend -Jport=8080 \
 -JnumExecutions=1 -JnumUser=1 -JrampUp=0 -JnumProducts=1 \
 -JthinkTimeMin=0 -JthinkTimeAdditionalRange=0 \
 -JpauseBeforeExecution=0 -JpauseAfterExecution=0 \
 -JloggingEnabled=false -JloggingSCIEnabled=false \
 -n -t t2-project-flexible.jmx

In the following table all the available parameters are listed and described:

Parameter	Description	Required?	Default value
hostname	address of the backend	yes	localhost / backend / uibackend
port	port of the backend	yes	8081 (local) / 8080 (within Docker network)
numExecutions	number of executions (sequential)	no	1
numUser	number of users (parallel)	no	1
rampUp	timeout (in seconds) until every user must have been started - one user will be started after every ($rampUp/ $numUser) second(s)	no	0
numProducts	number of products added to one order	no	1
thinkTimeMin	minimum amount of time (in milliseconds) a user needs to choose a product	no	0
thinkTimeAdditionalRange	additional amount of time (in milliseconds) of the normal distribution deciding when the user chooses a product once the timeout is over	no	0
pauseBeforeExecution	time in milliseconds to pause before an execution - can be useful to delay the start of the first request	no	0
pauseAfterExecution	time in milliseconds to pause after an execution - can be useful for pauses between multiple executions (numExecutions) or to extend the measurement time of the GMT runtime phase (important if there are asynchronous operations happening)	no	0
loggingEnabled	boolean value, if true for every request and pause a note for GMT will be created	no	false
loggingSCIEnabled	boolean value, if true a SCI note for GMT will be created right after the request POST confirm order is sent (GMT_SCI_R=1)	no	false

Local Testing

Configuration

Add JMeter bin path to your environment variables.

Open user.properties in the bin directory and change the value overall_granularity from 60000 to something smaller:

jmeter.reportgenerator.overall_granularity=1000

Simple Execution

jmeter -Jhostname localhost -Jport 8081 \
 -JnumUser=1 -JrampUp=0 \
 -JthinkTimeMin=1000 -JthinkTimeAdditionalRange=0 \
 -JloggingEnabled=true -n -t t2-project-flexible.jmx

Report Generation

RESULTS_DIR="fixed-single-100-users-30-sec-think-time--modulith-01"
mkdir $RESULTS_DIR
jmeter -Jhostname localhost -Jport 8081 \
 -JnumUser=1 -JrampUp=0 \
 -JthinkTimeMin=30000 -JthinkTimeAdditionalRange=30000 \
 -JloggingEnabled=false -n -t t2-project-flexible.jmx \
 -l $RESULTS_DIR/results.csv -e -o $RESULTS_DIR/report