How to find connection parameters for clients which override global timeout variables
(Doc ID 2524988.1)
Last updated on MAY 05, 2019
Applies to:MySQL Server - Version 5.7 and later
Information in this document applies to any platform.
If the session level values are greater than the global(s) for wait timeout, then these sessions may need to be manually killed before they become an issue for resourcing on a busy server.
An Example scenario can be one where the global values for wait_timeout / interactive_timeout are set quite low ( the default value is 8hours ), eg 1800 seconds for OLTP.
If the environment is heterogeneous and there are many different applications / users connecting to the DB, some may explicitly set the default values at the session level.
Currently by design , this will override the global value and in the specific case for timeouts, the clients will be able to reaming connected to the DB for longer that the DB global value.
This can be seen to have the potential to impact the DB's resources and therefor ongoing stability.
While manually killing the jobs might address the short term goal of reducing the open connection count, the DBA will want to contact the applicaiton administrators to have them update their session variables to better reflect the environment.
This information can be obtained from the SHOW GLOBAL PROCESSLIST for any idle threads grater than the server's global default.
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