Limit session resources

You can limit the resources available to individual sessions to more evenly distribute system usage, and prevent resource monopolization.

Set the following configuration parameters to impose limits on sessions:
  • SESSION_LIMIT_LOCKS limits the number of locks a tenant session can acquire.
  • SESSION_LIMIT_MEMORY limits the amount of memory that can be allocated for a session.
  • SESSION_LIMIT_TEMPSPACE limits the amount of temporary table space that can be allocated for a session.
  • SESSION_LIMIT_LOGSPACE limits the size of transactions within a session, based on the amount of log space that an individual transaction would fill.
  • SESSION_LIMIT_TXN_TIME limits the amount of time that a transaction is allowed to run within a session.

You can set the IFX_SESSION_LIMIT_LOCKS environment option in the session, to specify a lower lock limit than the SESSION_LIMIT_LOCKS configuration parameter value.

Session limits do not apply to a user who holds administrative privileges, such as user informix or a DBSA user.

Transactions and sessions that exceed a set limit are terminated by the session_mgr thread. The session_mgr thread starts when the database server starts, and remains inactive until a session limit is exceeded.