Heap size affecting migration time

This insights checks if your heap size is within the recommended range for your migration.

How does heap size affect migration time?

While exporting issues during the migration, we load their IDs into application memory. The more issues you have, the more memory we need to keep those IDs until entire export is finished. The migration assistant also exports many projects and issues in parallel to speed up the migration, so it’s good to have a substantially larger heap. The memory is released once export is done.

In newer assistant versions, we added more caching and improvements, so the heap doesn’t affect the migration time as much as in the past, but it’s still an important part. You can increase the heap just for the migration and decrease it later if your current heap size is enough for your instance.

Increase the heap size RECOMMENDATION

Follow these steps to identify the correct heap size and increase it, if needed.

Identify correct heap size for your instance

The table below shows the recommended heap size for different issue volumes, with some additional recommendations on CPU cores and system memory.

Learn more in How to speed up your Jira migration

Increase the heap size

You can increase the heap size in the setenv.sh or setenv.bat file in your Jira installation directory.

To increase the heap size:

1. Shut down your Jira instance.

2. Go to <Jira-installation-directory>/bin.

3. Edit the setenv.sh (Linux) or setenv.bat (Windows) file.

4. Add the recommended values in the JVM_MINIMUM_MEMORY and JVM_MAXIMUM_MEMORY properties, and save the file.

5. Start your Jira instance.

You can verify that the new values are in place by going to Administration > System > System info. The heap size is shown in the Java VM Memory Statistics section, where you can also check the current usage statistics.

Learn more in Increasing Jira application memory