This parameter sets the maximum size of the idle agent
pool.
- Configuration type
- Database manager
- Applies to
-
- Database server with local and remote clients
- Database server with local clients
- Partitioned database server with local and remote clients
- Parameter type
- Configurable online
- Default
- 100, AUTOMATIC [-1, 0 - 64000]
Note: The default value is subject to change by the DB2® Configuration Advisor after
initial database creation.
This configuration parameter is set to AUTOMATIC with a value of 100 as the default. A setting of -1 is still supported, and translates into a value of 100. When this parameter is set to AUTOMATIC, the database manager automatically manages the number of idle agents
to pool. Typically, this means that once an agent completes its work,
it is not terminated, but becomes idle for a period of time. Depending
on the workload and type of agent, it might be terminated after a
certain amount of time.
When using AUTOMATIC, you can still specify a value for the num_poolagents configuration parameter. Additional idle agents will always be pooled
when the current number of pooled idle agents is less than or equal
to the value that you specified.
Examples
- num_poolagents is set to 100 and AUTOMATIC
- As an agent becomes free, it is added to the idle agent pool,
where at some point the database manager evaluates whether it should
be terminated or not. At the time when the database manager considers
terminating the agent, if the total number of idle agents pooled is
greater than 100, this agent will be terminated. If there are less
than 100 idle agents, the idle agent will remain awaiting work. Using
the AUTOMATIC setting allows additional idle agents
beyond 100 to be pooled, which might be useful during periods of heavier
system activity when the frequency of work can fluctuate on a larger
scale. For cases where there are likely to be less than 100 idle agents
at any given time, agents are guaranteed to be pooled. Periods of
light system activity can benefit from this by incurring a less start
up cost for new work.
- num_poolagents is configured dynamically
- If the parameter value is increased to a value greater than the
number of pooled agents, the effects are immediate. As new agents
become idle, they are pooled. If the parameter value is decreased,
the database manager does not immediately reduce the number of agents
in the pool. Rather, the pool size remains as it is, and agents are
terminated as they are used and become idle again-gradually reducing
the number of agents in the pool to the new limit.
Recommendation
For
most environments the default of 100 and AUTOMATIC will be sufficient. If you have a specific
workload where you feel too many agents are being created and terminated,
you can consider increasing the value of num_poolagents while leaving the parameter set to AUTOMATIC.