By configuring application lazy start, you can release resources
that are being consumed by inactive dynamic clusters so that other cluster
instances in the cell can use these resources.
Before you begin
- Application lazy start requires that requests are routed through the on
demand router. To create an on demand router, see Creating ODRs
for more information.
- Internet Inter-ORB Protocol (IIOP) and Java™ Message Service (JMS) requests cannot
be used because they are not routed through the ODR.
- Create a dynamic cluster. See Creating dynamic clusters
for
more information. You can also configure application lazy start when you are
creating a dynamic cluster.
About this task
An application lazy start is the activation of the first application
server instance of a deactivated dynamic cluster when an application request
arrives. You decide which applications to deactivate and subsequently lazily
start. Use application lazy start if you have an environment in which the
ratio of the number of dynamic clusters to the number of nodes is high, and
if many dynamic clusters are not accessed for a long period. By using application
lazy start, you can increase the performance and efficiency of your environment.
Procedure
- Edit the dynamic cluster properties. In the administrative
console, click Servers > Dynamic clusters > dynamic_cluster_name .
- Select the Stop all instances during
periods of inactivity option.
- Set the Time to wait before stopping instances in minutes
if the application placement controller determines that the resource is required
by some other dynamic application cluster.
Results
The application placement controller tracks the amount of time that
a dynamic cluster has been inactive. If another dynamic cluster needs resources,
the application placement controller can stop the inactive dynamic cluster
after the specified time period. The resources that the inactive instance
are released for the other dynamic cluster. If a request arrives for the stopped
dynamic cluster instance, the lazy start controller is activated and at least
one server instance is started. In the meantime, HTTP error code 503 (server
unavailable) is generated. The error page informs you that the requested application
is starting and the request is resubmitted shortly.
What to do next
- Application lazy start only stops dynamic cluster instances if other dynamic
clusters need resources. If you want to stop dynamic cluster instances after
the specified time period even if the resources are not needed, configure
the proactiveIdleStop custom property.
- You can configure a custom error page for the ODR that can be used for
the 503 error. The error page can include an HTTP meta refresh tag that causes
the browser to automatically send the request again after a certain waiting
period. See Configuring ODRs
for more
information about configuring custom error pages.