Thank you so much creating this question as a public announcement.

We are currently facing the same issue with our RDS for MySQL 8.0.37 instance: freeable memory consistent drops, and swap usage surges once freeable memory falls below 1 GiB.

Upon reviewing the MySQL 8.0.38 and 8.0.39 release notes, we came across references to two memory leak fixes:

• Group Replication: Fixed a memory leak in /xcom/gcs_xcom_networking.cc. (Bug #36532199)
• Kerberos Authentication: Resolved a memory leak observed when running authentication_kerberos under Valgrind. (Bug #34482788, Bug #36570929)

(Source: MySQL 8.0.38 Release Notes)

However, we do not use either Group Replication or authentication_kerberos in our RDS MySQL setup. This leads us to wonder whether the release notes might not fully document the specific memory leak we are encountering.

We would greatly appreciate it if you could share whether you were using any of these MySQL features mentioned in the release notes when you encountered memory leak issues with RDS MySQL 8.0.37. Your input would be greatly helpful in helping us decide whether to upgrade from 8.0.37 to a newer minor version.

Thank you once again for sharing your experience, it has already been a tremendous help!