Additional Configuration

MySQL Configuration

Check Existing Value

Verify MySQL Parameter : `group_concat_max_len`, value should be 50000000.

  1. Login to MySQL Docker : docker exec -it qmetry85_mysql_1 bash
  2. Login to MySQL : mysql -u[username] -p[password] -A
  3. Check the parameter value using query : SELECT @@group_concat_max_len;
  4. If this value is lower than 50000000, follow the remaining steps to update this value
  5. Type "exit" to exit mysql and exit again, to exit the docker.

Update if the value is set less than 50000000

  1. Type df -h
  2. Go to the /var/lib two directories that end with path /merged.
    • For example : cd /var/lib/docker/overlay2/<...some random text....>/merged/home
    • One of these paths will contain `my.cnf`
    • Type ls to check the file.
  3. Edit the my.cnf file using command : vim my.cnf type i to go into insert mode.
  4. Check for parameter : group_concat_max_len, if it does not exist, add it, or else update its value to 50000000
    • group_concat_max_len=50000000
  5. Type Esc and then :wq to save and exit.
  6. Restart services using below commands
    • docker stop qmetry_app_1 qmetry_rds_1
    • docker start qmetry_rds_1
    • docker start qmetry_app_1

Verify the parameter value using steps above.

Tomcat Memory Configuration

(This is an additional step, which has to be done depending on your server hardware capability)

As the number of users and their connections in your environment increase, the amount of Java Virtual Machine (JVM) heap memory consumed on your servers will also increase. This guide explains how to increase the amount of memory allocated to your environment's JVM heap space.


  • If your server hardware does not have sufficient RAM installed, increasing the Java heap space may be ineffective or it may even reduce overall performance.
  • Java "out of memory" (OOM) errors can occur when the JVM attempts to use more memory than allocated by the Java environment's -Xmx parameter.
  • This procedure requires you to access and restart the docker.

Reference Values for Tomcat Heap Memory Configuration depending on your server memory :

Note : The below reference values apply to application server

Heap Memory ConfigurationSmall Teams Medium TeamsLarge Teams
< 50 Users< 500 Users500+ Users
MinRecommendedMinRecommendedMinRecommendedHigh End
Memory8 GB16 GB16 GB24 GB24 GB32 - 64 GB64 GB
Tomcat Heap Memory-Xms2g -Xmx4g-Xms4g -Xmx8g-Xms4g -Xmx8g-Xms8g -Xmx12g-Xms8g -Xmx12g-Xms8g -Xmx16g-Xms8g -Xmx30g

Execute the following commands on your server to increase memory size.

  • docker ps
  • docker exec -it <docker_name> /bin/bash
    • example : docker exec -it qmetry_app_1 /bin/bash
  • Change directory to path : /home/qmetry/QMetry/bin
    • cd bin
  • vim
    • Edit the default configuration for JAVA_OPTS parameter
    • The default configuration for heap memory are as follows. You can edit the file and update the highlighted values below by referring to the values specified in the above table and your server memory.
      • -Xms3g (Represents minimum 3 GB will be allocated to the QMetry Application)
      • -Xmx4g (Represents maximum 4 GB will be allocated to the QMetry Application)
      • Go to the second line and type letter i to go into insert mode, and update the values.

  • Save the file using Esc and then typing :wq to save and exit the file editior.
  • exit (exit the docker container)
  • docker stop <docker_name>
  • docker start <docker_name>