When the governor daemon is started (either by the db2gov front-end utility or by waking up), it runs in a loop. The first task it does is to check whether its governor configuration file has changed or has not yet been read. If either condition is true, the daemon reads the rules in the file. This allows you to change the behavior of the governor daemon while it is running.
After this, the governor daemon issues a snapshot request to obtain statistics for each application and agent working on the database.
| Note: | On some platforms, the CPU statistics are not available from the DB2 Monitor. Where this is the case, the account rule and the CPU limit will not be available. |
The governor then checks the statistics for each application against the rules in the governor configuration file. If a rule applies to an application, the governor can: force the application; change the application's priority, which indirectly changes all the agent priorities of both agents and subagents that are working for it on that node; or, change the schedule for the application which, indirectly changes the agent priorities working on the application, depending on the action specified by the rule. The governor writes a record of any action it takes to a log file.
| Note: | The governor cannot be used as an alternate means to adjust agent priorities if the agentpri database manager configuration parameter is anything other than the system default. (This note does not apply to OS/2 or Windows NT platforms.) |
When the governor finishes checking all of the applications, it sleeps for the interval specified in the configuration file. Once this time has elapsed, the governor wakes up and begins the execution loop again.
When the governor encounters an error or stop signal, it does cleanup processing before ending. The cleanup processing resets all application agent priorities (using a list of applications whose priorities have been set). It then resets the priorities of any agents that are no longer working on an application. This ensures that agents do not remain running with nondefault priorities after the governor ends. If an error occurs, a message is written to the db2diag.log file to indicate that the governor ended abnormally.
| Note: | The governor daemon is not a database application, and, therefore, does not maintain a connection to the database. (It does have an instance attachment, however.) The governor daemon can detect when the database manager ends because it can issue snapshot requests. |