Configure application lazy start

By configuring application lazy start, we can release resources that are being consumed by inactive dynamic clusters so that other cluster instances in the cell can use these resources.

• Application lazy start requires that requests are routed through the on demand router. For more information about creating an on demand router, read about creating ODRs.

• Internet Inter-ORB Protocol (IIOP) and Java Message Service (JMS) requests cannot be used because they are not routed through the ODR. Do not use application lazy start on dynamic clusters that run Session Initiation Protocol (SIP) applications.

• Create a dynamic cluster. For more information, read about creating dynamic clusters.We can also configure application lazy start when we are creating a dynamic cluster.

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 we 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, we can increase the performance and efficiency of your environment.

1. Edit the dynamic cluster properties. In the console, click Servers > Clusters > Dynamic clusters > dynamic_cluster_name.

2. Select the If other dynamic clusters need resources, stop all instances of this cluster during periods of inactivity option.

3. 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 were consumed by the inactive instance are released and made available for use by the dynamic cluster that requires additional resources. 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

• We can configure the application lazy start without the proactiveIdleStop custom property configured, once a application request arrives, the application server instance will start, but lazy start will never stop it in future.

• We can configure the application lazy start with the proactiveIdleStop custom property configured, the application server instance will stop after a specified time period.

• We 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. For more information about configuring custom error pages, read about configuring ODRs.

Subtopics

• (dist)(zos) Application lazy start
  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 we 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 time period.

• (dist)(zos) The lazy start controller
  The lazy start controller monitors the workload for dynamic clusters that you explicitly mark for deactivation. This controller triggers the placement controller to run off cycle and activate an inactive dynamic cluster when workload is detected. The lazy start controller also informs the placement controller when it is appropriate to deactivate these clusters.

Related concepts

Dynamic clusters

Intelligent Management: dynamic cluster administrative tasks

Related information:

Intelligent Management: dynamic cluster custom properties

Create ODRs

Create dynamic clusters