This article applies for JMeter version 5.3.
By default, JVM memory size will be 1GB alloted to Jmeter which will not suffice if you run a test with more than 100 Vusers. Also if you have not increased the JVM Memory size you might be running the test with headless mode which will be difficult to monitor unless you setup Grafana / Blazemeter/ .
To increse the JVM size you need to alter 2 files. Go to Jmeter Bin folder and open JMeter.bat file in a text editor of your choice.
Add these lines before get standard environment variables
set HEAP=-Xms512m -Xmx6g
set JVM_ARGS=-Xms512m -Xmx6g
Then open Jmeter.sh file
# add the Java9 args before the user given ones
JVM_ARGS="$JAVA9_OPTS $JVM_ARGS"
JVM_ARGS="-Xms1g -Xmx6g"
Now save both the files and the JVM Memory size increased to 6GB.
